Fédération des producteurs de porcs du Québec

Agro-Environmental Plan for the Hog Industry

EVALUATION OF LIQUID HOG MANURE
MANAGEMENT AND TREATMENT TECHNOLOGIES
by the
"Technological Transfer" Working Group
as part of the Agro-Environmental Plan for the Hog Industry

TABLE OF CONTENTS

Executive Summary

1. Context

1.1  Implementation of the Agro-Environmental Plan for the Hog Industry
1.2 Formation of the "Technological Transfer" Working Group
    1.2.1 Mandate of the Working Group
    1.2.2 Composition of the Working Group

2. Summary Description of the Agro-Environmental Problems Facing the Hog Industry

2.1 Farm Surpluses of Liquid Manure
2.2 Regional Surpluses of Liquid Manure
2.3 Odour Generation
2.4 Sensitive Environments
2.5 Possible Solutions

3. Methods

3.1 Liquid Manure Additives
3.2 Liquid Manure Treatment Concepts
    3.2.1 Proposed Concepts
    3.2.2 Evaluation Elements
    3.2.3 Information Requested from Promoters

4. Analysis of Results

4.1 Description of Different Treatment Processes
4.2 Level of Development
4.3 Technical Balances
    4.3.1 Agronomic and Environmental Balances
    4.3.2 Energy Balance
    4.3.3 Economic Balance
4.4 Potential Odour Reduction
4.5 Emergency Measures

5. Discussions

5.1 Mechanical Processes
    5.1.1 Roofs
    5.1.2 Separation by Natural Sedimentation
    5.1.3 Mechanical Separation
    5.1.4 Membrane Filtration
5.2 Biological Processes
    5.2.1 Aerobic
    5.2.2 Anaerobic
    5.2.3 Composting
    5.2.4 Filtering Marshes
    5.2.5 Use of Bedding
5.3 Chemical Processes
5.4 Thermal Processes
    5.4.1 DEC Group
    5.4.2 Progest
    5.4.3 Recyc-Sol
5.5 Physico-Chemical Processes
    5.5.1 Oligolysis
    5.5.2 Settling or Separation using Coagulants and/or Flocculants
5.6 Other

6. Conclusions

6.1 Criteria for Selection and Evaluation of Liquid Manure Management and Treatment Techniques and Technologies in the Quebec Context
6.2 Existing and New Techniques for Improved Liquid Manure Management
    6.2.1 Reducing the Nutrient Load of Liquid Manure
    6.2.2 Reducing Volume
    6.2.3 Managing Liquid Manure in Two Fractions: Solid and Liquid
    6.2.4 Reducing Odours
6.3 Technologies Currently Known or under Development
    6.3.1 Observations
6.4 Areas of Research and Development for Liquid Manure Management and Treatment Technologies
    6.4.1 Short Term
    6.4.2 Medium and Long Term
6.5 Working Approach for Liquid Manure Additives

7. Recommendations

7.1 Criteria for Selection and Evaluation of Liquid Manure Management and Treatment Techniques and Technologies in the Quebec Context
7.2 Existing and New Techniques for Improved Liquid ManureManagement
7.3 Technologies Currently Known or under Development
    7.3.1 Follow-up to Observations
    7.3.2 Approach to be Developed for Liquid Manure Treatment
7.4 Areas of Research and Development for Liquid Manure Management and Treatment Technologies
7.5 Development of a Working Approach for Liquid Manure Additives
7.6 Distribution of the Report
7.7 Follow-up

8. References

APPENDICES

List of Treatment Concepts Established by the Working Group
List of Criteria for the Evaluation of Treatment Processes
Explanatory Brochure for Promoters

Summary
of the Evaluation Report on
Liquid Hog Manure Management and Treatment Technologies

SUMMARY

INTRODUCTION

• determine the criteria for evaluating liquid manure management and treatment technologies in a Quebec context
• identify and evaluate management and treatment technologies that are known or that are in the process of being developed
• identify research needs in the area of treatment technologies
• define a working approach for liquid manure additives.

METHODS

An exhaustive list of 71 treatment technology concepts either known or in the process of being developed was established in May 1997. The concepts of 38 promoters were submitted and 32 technologies were evaluated according to predetermined data based on about 40 environmental, technical, agricultural, economic and social criteria.

SITUATION

Potential treatment technologies

Other processes still in the early stages of development also show a certain potential (Appendix 2). However, these technologies will require medium to long-term development prior to marketing.

Currently the processes capable of providing complete treatment are mostly at the laboratory testing or farm implementation stage. Major investments are required to permit the emergence of appropriate and effective systems.

Liquid manure management techniques

A number of techniques may already be used on the farm to significantly improve the liquid manure management system. As a general rule, these practices are required for treatment technologies to be introduced.

• optimization of feeding
• water-saving drinking systems
• establishment of windbreaks
• installation of roofs on storage structures
• mechanical separators
• use of bedding

ADDITIVES

RECOMMENDATIONS

Selection of treatment technologies

• universalize the use of criteria for evaluating management and treatment technologies developed by the Working Group.

Scaling-up and development of technologies

• inform hog farms that no process is at the marketing stage.
• suggest that subsidizing organizations financially support the concepts identified.
• suggest that promoters join with agricultural, environmental and economic partners in pursuing the development of their technologies.
• prioritize the development and/or demonstration of complete treatment technologies for liquid manure.
• develop unique methods to follow up the implementation of subsidized projects;
• require promoters to provide a reliable operating budget as a condition of financial assistance.

Liquid manure management

• communicate techniques to producers and other agricultural stakeholders in order to optimize the liquid manure management system and increase short-term use of manure.

Evaluation of liquid manure additives

• develop a protocol for testing and evaluating additives so that Quebec can adopt a "registration" type procedure.
• develop methods for quantifying odours and ensuring the safety and technical effectiveness of additives.
• checking the possibility of establishing a standard for this type of product with the Bureau de normalisation du Québec (BNQ).

Follow-up

• make the Fédédration des producteurs de porcs du Québec responsible for following up the recommendations.
• use the "Technological Transfer" Working Group for technical support.

1. CONTEXT

1.1 Implementation of the Agro-Environmental Plan for the Hog Industry

Objective of the Agro-Environmental Plan

"To ensure that hog production is practised and developed on an environmentally sustainable basis by reconciling economic and social requirements."

• Fédération des producteurs de porcs du Québec (FPPQ)
• Union des producteurs agricoles (UPA)
• Ministère de l’Agriculture, des Pêcheries et de l’Alimentation (MAPAQ)
• Ministère de l’Environnement et de la Faune (MEF)
• Association québécoise des industries en nutrition animale et céréalière (AQINAC)
• Coopérative Fédérée de Québec (CFQ)
• Union québécoise de la conservation de la nature (UQCN)
• Union des municipalités régionales de comtés (UMRCQ)

1.2 Formation of the "Technological Transfer" Working Group

More specifically, the group has studied the various techniques and technologies proposed as alternatives to conventional liquid hog manure management. Through its work, the group has been able to focus various areas of expertise on a single joint effort. Its recommendations are submitted to the members of the multi-stakeholder committee.

1.2.1 Mandate of the Working Group

The Working Group has been working since March 11, 1997 on the preparation of this report. Its mandate was to establish guidelines for liquid manure management and treatment technologies and to identify concepts offering interesting possibilities for the hog producers of Quebec.

Mandate of the Working Group

• Determine the criteria for selecting and evaluating liquid manure management and treatment techniques in the Quebec context.
• Identify existing and new techniques for improved liquid manure management.
• Evaluate the different technologies that are currently known or under development and prepare recommendations on them.
• Recommend avenues of research and development for liquid manure management and treatment technologies.
• Develop a working approach for liquid manure additives (enzymes, perfumes, etc.).

1.2.2 Composition of the Working Group

The Working Group consists of 12 researchers and practitioners specializing in the management and treatment of liquid manure. The complementary nature of their areas of expertise is essential to their evaluation of concepts ranging from engineering and agronomy to microbiology.

Each member of the Working Group has sworn in writing to maintain the confidentiality of the information submitted by the promoters. The Working Group thus cannot divulge any information on trade secrets.

2.  SUMMARY DESCRIPTION OF THE AGRO-ENVIRONMENTAL PROBLEMS
      FACING THE HOG INDUSTRY

Livestock production on liquid manure has, for a number of years, been associated with a number of environmental and social problems in Quebec. These problems have been particularly acute in the case of the hog industry, largely because of its rapid development in recent decades. Certain aspects of this development have had significant direct impacts on environmental management, particularly with respect to the quality and availability of water resources, in addition to social impacts.

2.1 Farm Surpluses of Liquid Manure

2.2 Regional Surpluses of Liquid Manure

2.3 Odour Generation

Building and Storage Odours

The odours generated by hog production buildings and liquid manure storage structures are permanent in nature, low in intensity and limited to the vicinity of these structures.

Odours during Spreading

The disposal of liquid manure generally involves a number of steps: it is first homogenized by agitation, then removed from storage and finally spread in the field. These activities expose the liquid manure to the air and permit the release of the gases dissolved in it. These gases, produced by fermentation of the liquid manure under anaerobic conditions, are responsible for its characteristic odour. Spreading techniques involving sprinkling fragment the liquid manure into droplets and release more of these gases and associated odours. Spreading thus generates intense but temporary odours over large areas.

2.4 Sensitive Environments

Spreading can also represent a serious environmental risk of contaminating ground and surface water and soil, but for different technical reasons, including improper selection of spreading methods and times (runoff, leaching or volatilization of contaminants, such as nitrogen, phosphorus, pathogens or metals).

2.5 Possible Solutions

In addition to good management, treatment technologies can play an important role in solving these problems. In the case of operations or regions with a manure surplus, these technologies use various processes to concentrate the nutrient load of the liquid manure in smaller volumes or even reduce it. This alternative is designed to facilitate the transportation of the fertilizers to receiving farms or zones. These treatment technologies can also improve the quality of the product and increase demand among receiving farm operations, thus permitting a larger proportion of the liquid manure produced in the area to be used locally.

3. METHODS

3.1 Liquid Manure Additives

The information currently available on liquid manure additives does not allow a complete analysis of their performance. In fact, the results reported in the literature are often contradictory and the protocols used to determine the effect of additives on odours are often incomplete. Consequently, the Working Group cannot make a valid evaluation or offer recommendations on their effectiveness. Additives have therefore been considered separately.

3.2 Liquid Manure Treatment Concepts

3.2.1 Proposed Concepts

In May 1997, the Working Group established the most exhaustive possible list of all treatment concepts currently known or under development in Quebec. In the course of its work, a number of new promoters were identified and their proposed concepts added to this list. By the end of the evaluation process, the list included 71 concepts. (Appendix 1 - List of Treatment Concepts Established by the Working Group)

While the assigned mandate did not include evaluation of the European and American treatment processes, these were discussed by the members of the Working Group. In addition, some of the concepts listed in the present document are based on European R&D efforts currently being adapted or tested in Quebec.

3.2.2 Evaluation Elements

The Working Group benefitted from the general expertise of its members, including their familiarity with treatment technologies under development elsewhere in the world. Most of its members have participated in previous task forces on this subject, in France, the Netherlands, Denmark and the United States.

It should be noted that concern in Europe is focused primarily on the "nitrogen" problem, while in Quebec the issue is considered more generally, including in particular the problems of "phosphorus" and "greenhouse or acid precipitation gases". In addition, differences in regulatory, environmental, climatic, energy and economic conditions are often significant and have an enormous impact on the evaluation of the proposed solutions.

The Working Group therefore feels that the work required to complete the technical development of the most promising procedures in no way duplicates that performed to date in Europe or elsewhere.

3.2.2.1 Response to the Problem

Every hog farm faces a specific situation. The evaluation of the treatment concepts must take into account their ability to deal with their specific agro-environmental situation. These situations can range from:

• Farms with a surplus of liquid manure for their own fertilization needs, located in a region with a surplus of farm manure;
• Farms with a surplus of liquid manure for their own fertilization needs, located in a region without a surplus of farm manure;
• Zone sensitive to contamination of ground or surface waters (topography, type of soil, etc.);
• Spreading odours;
• Building and storage odours.

3.2.2.2 Performance Criteria

The Working Group has developed an evaluation grid based on over 40 parameters relating to environmental, technical, agronomic, economic and social impacts. (Appendix 2: List of Criteria for the Evaluation of Treatment Processes)

It is essential that the environmental impact of the technologies be fully understood. For instance, is the removal of nitrogen by a given process really a gain? Is this purification of the liquid manure achieved by releasing substances into the atmosphere which may promote the greenhouse effect or acid precipitation? May the use of certain chemicals generate byproducts containing harmful residues? These are some of the questions which must be answered in properly evaluating a technology.

3.2.2.3 Liquid Manure Management Chain

The management of liquid manure begins with its production in the building and ends with its final disposal through application to the crops or the marketing of byproducts, and involves a number of intermediate handling stages. Flow charts can be used to illustrate the different links in the management chain, either in general (Figure 1) or in detailed form (Figure 2). More or less significant losses of nutrient elements can occur at each stage in this management chain. All of the interrelations between each of the stages must be taken into consideration.

Various technologies may modify or eliminate some of the links in the conventional management chain. For all practical purposes, no technology can replace all of the stages in this management chain. It may, however, eliminate some and/or add others (Figure 3). The true potential of any technology in comparison to conventional management can be determined only by examining the whole of the new liquid manure management chain which it generates.

 

FIGURE 1 :BASIC FLOW CHART FOR CONVENTIONAL LIQUID MANURE MANAGEMENT

FIGURE 2 :DETAILED FLOW CHART FOR LIQUID MANURE MANAGEMENT

FIGURE 3 :DETAILED FLOW CHART OF AN ALTERNATIVE TECHNOLOGY; "TREATMENT "

 

3.2.3 Information Requested from Promoters

To ensure a complete, objective evaluation, the promoters were asked to submit information in a number of areas pre-established by the Working Group. The promoters were provided with brochures explaining the method and the information requested. (Appendix 3: Explanatory Brochure for Promoters)

The promoters who agreed to participate in the exercise were asked to indicate the problem(s) and level(s) of application at which their technologies are directed. This information is important since some processes may be better suited or more useful for certain problems than for others.

Information Requested :

• Level of development.
• Identification of the process in the conventional liquid manure management chain.
• Environmental, agronomic, energy and economic balances.
• Estimated potential for odour reduction.
• Emergency measures in the event of failure of the treatment system.
• Hypotheses on which the data and information submitted are based and justifications for these hypotheses.

   

4. ANALYSIS OF RESULTS

4.1 Description of Different Treatment Processes

The majority of the treatments involve one of five major types of processes: mechanical, biological, chemical, thermal and physico-chemical. Some use more than one. The treatment may be designed for application on the farm or directed at a large or small group of operations (semi-collective or collective).

Of the 71 promoters of technologies identified, 38 submitted proposals and 33 failed to respond. The promoters identified late in the evaluation process had little time to prepare their submissions. As a result, the Working Group is unable to offer detailed comments on their concepts.

Analysis reveals that 50% of the 32 files examined include phase separation, normally at the beginning of treatment. In addition, 34% of the treatments evaluated use aerobic digestion and 16% an anaerobic system as their primary process.

4.2 Level of Development

With the exception of the roofs, mechanical separators and oligolysis, none of the treatment concepts studied have gone beyond large-scale pilot testing. In fact, more than 30% are in the concept stage, 22% in laboratory testing and 19% in pilot testing. Only 28% of the concepts have reached large-scale pilot testing or subsequent stages. More representative technical and economic data on the concept are available in these cases (Table 2).

4.3.1 Agronomic and Environmental Balances

Agronomic and environmental balances illustrate what becomes of the different components of liquid manure at each stage in the proposed treatment chains. In the case of nitrogen, for instance, the promoters must specify the forms and distribution of the nitrogen present initially in the raw liquid manure and in the various solid, liquid and gaseous outputs produced by the treatment.

The precision of these balances varied with the level of development of the promoters’ operations. Processes in the concept state offered only theoretical balances, since no experimental data were available. With only 28% of the technologies at the large-scale pilot testing stage, few balances were supported by actual measurements.

 

4.3.2 Energy Balance

The energy consumption of the treatment concepts was also examined. No complete energy balances were submitted.

 

4.3.3 Economic Balance

Since none of the processes have reached the marketing stage, the balances submitted were based entirely on measurements at the laboratory or pilot testing level. Most of the values submitted are thus hypothetical. According to the figures supplied by the promoters, treatment costs range from $2 to $17 per cubic metre of raw liquid manure.

Most of the promoters, however, present an overall treatment cost per cubic metre with no indication of the potential for variation on the basis of the size of the treatment unit, the transportation distances required for supply or for the disposal of byproducts or application at the farm or regional level. In addition, few promoters have properly analyzed the potential market for their technologies. How can the proposed concept enter the market? How much of the market can it capture? What proportion of the liquid manure surplus can the concept handle? All of these questions remain unanswered.

Since no bases have been given for the promoters’ estimated operating and acquisition costs, it is impossible to establish a list of average costs. These are closely related to the proposed degree of treatment of the raw liquid manure, and must await the results of future tests and more detailed, better supported economic studies. Because of the fragmentary information submitted and the complexity of the task, we have been unable to perform these evaluations.

4.4 Potential Odour Reduction

According to the literature, however, certain treatment technologies offer significant capacity for odour reduction. For example, the aerobic and anaerobic processes and the use of bedding have a known potential for odour reduction.

4.5 Emergency Measures

5. DISCUSSIONS

5.1 Mechanical Processes

5.1.1 Roofs

Roofs are not considered a treatment as such. However, they constitute an interesting alternative to standard liquid manure management. In fact, the installation of roofing on storage tanks permits better nitrogen conservation and reductions in storage odours and in the volume of the liquid manure to be managed by preventing the collection of precipitation. As a result, compared to uncovered storage, the liquid manure provides better nutrient value per volume. However, the construction of roofs on tanks over 20 metres in diameter is very costly. According to certain studies, ice is slower to melt in covered tanks in the spring, and may pose a problem when removing the manure from storage.

Two files on roofs were submitted: F. Bernard and Guy Valois Plastics.

Status: Commercial demonstration

5.1.2 Separation by Natural Sedimentation

Separation is an interesting alternative to conventional liquid manure management. It is a passive technique which allows the solid particles of the liquid manure to settle to the bottom of the storage structure. Because of the small size of the particles present in liquid manure, effective separation requires long retention times. This technique can thus be effectively applied in existing storage structures (more than 200 days retention time) at no additional cost since the only change is to the liquid manure management process.

When surplus phosphorus is a problem, this is an interesting approach since it permits extraction of the nutrient elements associated with the solid particles, representing 15 to 25% of the initial volume, from the concentrated fraction at the bottom of the pit. For instance, as much as 70% of the phosphorus and 35% of the nitrogen can be extracted, together with only 20% of the potassium. The supernatant is lower in phosphorus and nitrogen than the raw liquid manure but its nitrogen:phosphorus ratio is generally better suited to crop requirements.

5.1.3 Mechanical Separation

Mechanical separators are designed to improve the effectiveness of natural sedimentation and, consequently, offer the same potential. These systems may use strainers, roller, screw, belt or rotary presses, centrifuges, etc. Some processes, such as those using centrifuges and belt or rotary presses, require coagulants and/or flocculants to improve their performance. These are classified as physico-chemical processes (section 5.5.2).

Separators are of particular economic interest when the manure must be transported long distances for spreading and complementary processes are available to recover the solid fraction. Hog producers who are not in a surplus position will find separators more difficult to justify on an economic basis.

Of the numerous promoters of separators, two, Alfa-Laval and F. Bernard, participated in the evaluation process. In another 14 files, separation was used as part of a more complete treatment chain.

Status: Commercial demonstration

5.1.4 Membrane Filtration

Filtration (ultrafiltration, microfiltration, nanofiltration, reverse osmosis) is an operation which uses membranes to separate solid materials mechanically from the liquid in which they are found. The distinction between ultrafiltration, microfiltration and osmosis is normally based on the size of the particles or molecules retained. Microfiltration membranes can remove suspended particles between 0.1 and 10 microns in diameter. Ultrafiltration permits the filtration of dissolved molecules and particles between 10 and 1000 angstroms ( = 10^-10 metres) in diameter, at high or low pressure.

Reverse osmosis is a separation process involving the use of a membrane and a high pressure gradient. It involves a microscopic separation based on the size and nature of the solutes to be retained in comparison to the nature and structure of the membrane. (Bouchard and Lebrun, 1988). This process permits the separation of elements as small as ions. Normally, these are approximately 1 to 10 angstroms in diameter. The substances dissolved in liquid manure (e.g.: nitrates, phosphates, ammonia nitrogen, potassium, etc.) can thus be recovered.

The effectiveness of filtration is closely connected to the membranes used. The membranes available on the market are not necessarily effective for liquids containing high levels of organic matter, as in the case of liquid manure. Improperly selected membranes can become clogged by the large quantity of solids contained in the liquid manure. These processes thus require preliminary removal of the majority of the solids suspended and dissolved in liquid manure. Clogging then becomes less rapid, and the filter or membrane is more effective.

Sequential ultrafiltration and reverse osmosis are already used in agriculture for the production of maple syrup. The promoters propose a complete treatment designed to allow application on the farm and discharge of the effluent into watercourses. Membrane filtration is preceded by solid-liquid separation.

This treatment technology has aroused the interest of the Working Group since it is one of the few capable of extracting nitrogen, phosphorus and potassium from the liquid fraction. Despite its potential to produce effluents which can be discharged into watercourses, certain questions remain. What is the life expectancy of the membranes? What is the operating cost (energy and maintenance)? Given the solid content of liquid manure, the risk of clogging must be seriously considered.

According to the promoters, recent research and development on membranes have solved these problems. If the membrane can in fact do the job and the final cost of the treatment is competitive, this concept offers very interesting potential. The efficiency and life expectancy of the membrane will have a strong impact on its economic performance. The promoters would be well advised to document the sanitary qualities (pathogens and viruses) of the effluent as well. Additional larger scale studies will provide more complete answers to these questions.

Finally, the Working Group feels that all or part of this system could be very useful as a polishing method in combination with other forms of treatment.

A single concept in this category was submitted by the group formed by Purin-Pur and the Centre national en électrochimie et en technologies environnementales (CNETE).

Status: Pilot testing

5.2.1 Aerobic

Aerobic treatment involves surface or subsurface aeration to promote the development of aerobic flora. The oxygen introduced permits microbial and enzymatic activity capable of oxidizing organic matter (Buelna et al., 1993). The resulting decomposition significantly reduces the release of odours from the liquid fraction. Aeration can be performed directly in the liquid manure cellar or in outdoor storage facilities. However, the possible development of dangerous foams or gases as the result of a breakdown represents a significant problem (CRIQ et al., 1995).

Depending on the type of process, aeration may result in losses of such gases as ammonia (desorption), NO_x and N₂O to the atmosphere. These gases can be considered atmospheric contaminants.

Eleven files propose treatment systems involving aerobic digestion: Bio-Fert, Biosor, Biooxyblock, Ekokan Inc., INRS-Eau, Little River Pond, M. Mikhail, NCL-Enviroteck, Phytobact, Sani-porc and Stratech.

5.2.1.1 Bio-Fert

The Bio-Fert technology, developed by the Soprin ADS group, is designed for application on the farm or in a regional treatment centre. The technology is based on aerobic decomposition, without the addition of microbial or chemical products. The innovative nature of the concept lies in its use of a continuously operating modular bioreactor using compressed air.

The Working Group considers this an interesting and promising process. It can be incorporated in the farm’s liquid manure management system without the addition of major infrastructures, thus eliminating a large proportion of the storage tanks if it is combined with an effluent polishing process. Some concerns remain, however, with respect to gaseous emissions (N₂O) and the large volumes of sludge to be managed.

Status: Pilot testing

5.2.1.2 Biosor

The Biosor technology involves an aerobic biofiltration process. Its promoter, the Centre de recherche industrielle du Québec, proposes a complete system designed to permit effluent discharge into watercourses. The treatment consists of a number of stages: settling, sludge stabilization, prefiltration, treatment by the main biofilter and effluent polishing by a second biofilter.

The Working Group considers this an interesting system. From the environmental standpoint, however, it raises a number of questions. In fact, little documentation is provided on metal and phosphorus saturation of the biofilter, the life expectancy of the biofilter, the gas balance, disposal of the biofilter and stabilization of the settling sludges. In addition, the promoter offers few details on polishing methods. This stage of the treatment was undergoing laboratory testing at the time the report was prepared.

Further details and explanations are required with respect to installation and operating costs, as with a number of promoters. In addition, little documentation is provided on the basic hypotheses.

Status: Large-scale pilot testing for the basic system without discharge into watercourses

Laboratory testing for polishing prior to discharge into watercourses

5.2.1.3 Biooxyblock

The Biooxyblock concept involves a modification of the traditional activated sludge process. It is a complete chain designed for application either on the farm or in a central facility.

This technology has never been tested with liquid manure. The data provided by the promoter relate to sewage, which has a pollutant load as much as 200 times lower than the concentrations normally encountered in liquid manure.

Status: Pilot testing

5.2.1.4 Ekokan Inc.

This promoter proposes a complete liquid manure treatment system for application on the farm. The raw liquid manure is strained and pressed and the solid fraction either composted, granulated or spread. The liquid fraction is mixed with the wash water or diluted and placed in the bioreactor. There is thus a significant increase in the volume to be managed.

This concept has a number of problems. Extensive dilution is required and it is not certain that the technology will work with liquid hog manure. The Working Group does not believe that three different types of microbial treatment are required, since a single thermophilic treatment would be adequate. It thus considers the proposed system complex and probably costly.

The Working Group feels that more tangible results are required to justify further analysis.

Status: Large-scale pilot testing

5.2.1.5 Little River Pond Mill

A single promoter, Little River Pond Mill (Éco-Guide Environnement), suggests a treatment based on aerated storage. According to the promoter, this is a partial treatment designed for use on the farm in liquid manure tanks. A windmill on a floating base operates a submerged propellor which gradually brings the contents of the storage tank to the surface for exposure to the open air.

This system may have some effect on odour reduction during storage. It is, however, a partial treatment and the microorganisms responsible for the objectionable odours are still present. As a result, odours may persist on removal from storage and spreading.

From the environmental standpoint, this system releases gases (particularly ammonia) into the atmosphere. Under these circumstances, the committee cannot recommend its widespread use.

Status: Pilot testing in Quebec and marketing in Ontario

Liquid Sewage Management with the Little River Pond Mill ®

5.2.1.6 INRS-Eau

The Institut national de recherche scientifique-Eau proposes an aerobic system using tubular membranes and hollow fibres. This system was developed to treat effluents from the processing of cellulosic material, particularly those produced in the manufacture of bleached chemi-thermomechanical pulp. The promoters now hope to adapt it for the treatment of liquid hog manure on the farm.

The Working Group cannot offer any comments since few data have been submitted.

Status: Concept definition for liquid hog manure

5.2.1.7 Mourad Mikhail

The project consists of solid-liquid separation on the farm followed by thermophilic aerobic treatment of the liquid fraction in a central facility. This type of treatment results in irreversible losses of large quantities of nitrogen into the atmosphere in the form of ammonia.

A large proportion of the phosphorus is found in the solids and thus remains on the farm, a major disadvantage of this concept. Because of the possibility of phosphorus surpluses, the promoter might be well advised to consider separation at the central site to permit management of the phosphorus as well.

As in a number of other cases, insufficient information has been submitted to permit discussion of the technical, economic and environmental effectiveness of the technology.

Status: Concept definition

5.2.1.8 NCL-Enviroteck

In this treatment system, which is designed for application on the farm, liquid manure is transferred from its storage tank into another tank containing a biosolution. The liquid manure is then pumped into the bioreactor following treatment. Once treated, it is stored in a tank or discharged directly into a watercourse. If the results are unsatisfactory, the liquid manure may be retreated.

It appears unlikely that the effluent can be discharged directly into a watercourse after a single session in a bioreactor. Bioreactor effluents generally require polishing before their discharge into watercourses. The Working Group questions the concept’s potential for success. A great deal of information is still required for complete analysis.

Status: Laboratory testing

5.2.1.9 Phytobact

The concept, designed for application on the farm, consists of four principal stages: solid-liquid separation of the raw liquid manure, composting of the solid phase, biological aerobic thermophilic treatment of the liquid fraction and purification of the biotreatment effluent by filtration through the roots of reeds.

Little information is provided to describe the effectiveness of the proposed process. The aerobic thermophilic treatment is autothermal in the case of liquid hog manure and pasteurizes the liquid manure, thus reducing microorganisms. This concept permits the recovery of the large quantity of nitrogen which is volatilized during the process. A great deal of work remains to be done, however, to ensure that filtering marshes constitute an appropriate and applicable polishing method.

At the time that the report was being prepared, the promoter had not yet tested the process. The portion preceding marsh filtering, however, corresponds generally to a system on which previous pilot testing has been performed.

Status: Pilot testing for the aerobic treatment

Concept definition for the marsh

5.2.1.10 Sani-porc

Énergie-Bio G.V. proposes the Sani-porc concept for application on the farm. It is a very complex process involving a number of technologies (ultraviolet lights, chlorination, press with flocculants, etc.). It consists of four principal stages: processing of the liquid manure in the reactor, biological treatment in a rotary digester, purification of the treated liquid manure and treatment of the gases extracted from the liquid manure.

The results are embryonic. Of all the technologies examined by the Working Group, this one involves the largest number of steps. The number and arrangement of these steps do not appear to be finalized. A great deal of additional work will be required to optimize the process and, if applicable, for further laboratory studies.

Status: Laboratory testing

5.2.1.11 Stratech

Stratech proposes a liquid manure treatment system using a sequential aerobic bioreactor and a peat filter to polish the supernatant before discharge. The sludge is treated with lime and then solidified on a drying or freezing/thawing bed, depending on the season. This system uses all of the farm’s liquid manure.

Questions arose on a number of points: winter operation (primarily polishing), operation of the freezing/thawing bed unverified with liquid manure sludge, operation of the nitrification-denitrification stage unclear and uncertain adaptability. In contrast, while relatively costly, this system offers interesting technical potential.

Status: Laboratory testing

5.2.2 Anaerobic

Anaerobic treatments promote the development of microorganisms in the absence of free oxygen. Anaerobic digestion of organic matter involves three successive phases, hydrolysis, acidogenesis and methanogenesis, in which different microbial populations come into play. The longest established anaerobic treatment is the mesophilic process. In this process, liquid manure is maintained at a temperature between 30 and 35 °C to permit sufficiently rapid growth of the bacteria specific to methanogenesis. Given the climatic conditions existing in Quebec, this does not appear to be an interesting alternative since much of the biogas produced by the process is required to heat the digester. The same is true of the thermophilic process (60-65 °C), which presents an even greater problem of stability. These treatments would thus be more appropriate at regional centres where investment and operating costs per volume of liquid manure treated are lower.

In zones with a manure surplus, this type of process would be of greater interest in combination with solid-liquid separation. In fact, for all practical purposes, this anaerobic treatment offers no reduction in nutrient value or volume. However, a large proportion of the organic matter is mineralized in the course of the treatment, with the result that the organic load of the treated liquid manure is much lower than that of raw liquid manure. The value of the treated liquid manure in terms of agronomic availability, however, is improved. Odour production is said to be reduced and the treated liquid manure is unlikely to release further odours, in view of its reduced organic load. These two factors may thus assist hog producers faced with surpluses of liquid manure in finding recipients.

This is the second most popular type of process among the promoters listed. A total of six promoters use this process as the primary means of treatment. They are: Agriculture and Agri-Food Canada, Forces-Massicotte Consortium, Escan, GESTEA and Société d’études d’assainissement.

(psychrophilic: 10 to 20 °C) and to liquid hog manure. These microorganisms are maintained in two sequential bioreactors, each of which has a retention time of approximately 15 days. This process is designed to deodorize the liquid manure and stabilize the organic matter which it contains by mineralization. In addition, it permits recovery of the biogas produced by this process for immediate use on the farm.

The system, as designed, offers the following advantages:

• low investment and operating costs (since the temporary manure storage unit can serve as a bioreactor, a process requiring no energy input);
• improvement of the product (conservation of nitrogen and greater availability of nutrient elements) and thus of demand;
• possible use of the biogas produced (to heat water or air in the building);
• easy integration of the process with normal farm activities.

However, this process does not reduce the quantity or volume of fertilizers to be managed. In a zone with a manure surplus, then, this process can be used only if demand for the product is a determining factor in the situation within the zone. Furthermore, since the concept is only at the pilot testing stage, technical, environmental and economic data are still unavailable, particularly as regards the stability of the process, the impact of pesticides on the process, etc.

Status: Pilot testing

5.2.2.2 Forces-Massicotte Consortium

This process is designed to transform liquid manure into a bactericidal agent using the principles of anaerobic digestion. It is intended for use at a central site.

Because of the limited information submitted by the promoter, the Working Group has been unable to perform a detailed analysis.

Status: Laboratory testing

5.2.2.3 Escan

This centralized treatment is designed to use primary and secondary pulp mill sludges combined with other organic residues, such as liquid hog manure, for biomethanization. According to the promoter, the biogas produced, consisting primarily of methane and carbon dioxide, would be sold to gas distributors or transported to an electrical power generating plant. The digested, dehydrated sludge would be sold as an organic amendment and/or fertilizer.

Since the promoter did not provide any further information or balances, no valid analysis could be performed.

Status: Concept definition for liquid hog manure

5.2.2.4 GESTEA

The treatment proposed by Gestion des techniques de l’eau et des aliments (GESTEA) is intended for application on the farm and involves a number of processes. Lack of information precluded a proper analysis.

Status: Concept definition for liquid hog manure

5.2.2.5 Société d’études d’assainissement

The proposed technology is designed for use in a mobile unit, on the farm or even at a central site. The organic matter is crushed and concentrated, then digested under anaerobic conditions. The process uses a temperature of 35 C. The resulting biogas can be used to heat the digester. This system permits deodorization of the liquid manure (during storage and spreading) and recovery of the volatile compounds.

The Working Group was left with a number of questions with respect to costs (energy, maintenance, investments, etc.), the risk of explosion and suitability for farm use. Where liquid manure is in surplus, the concept does not permit reduction of the volumes to be managed and is of little interest. It would have to be combined with other technologies permitting such a reduction in volume.

Status: Laboratory testing

5.2.3 Composting

Composting is a biological process which promotes the aerobic decomposition of various organic wastes to obtain a stable, humus-rich mixture known as compost. Liquid manure can be mixed with wood residues to produce compost. However, the availability of quality inputs at reasonable cost may limit widespread use of this process. Depending on the techniques used, it may entail environmental losses of varying severity. Because of the volumes of materials to be handled and transported in supplying a composting unit, this technique appears more appropriate for farms not dealing with surpluses. This depends on the regional surplus problem.

Two of the numerous promoters of composting, Temvec and the University of Quebec at Rimouski, participated in the evaluation process.

5.2.3.1 Temvec

The concept proposed by Temvec consists of a central composting plant. The organic matter used is obtained from municipal wastes and includes sawdust, bark, recycled fibres, etc. The concept may be interesting in specific cases where municipal authorities, industries and hog producers are located close enough to work in partnership. Application to the hog industry as a whole, however, would be difficult. This approach depends entirely on the availability of reasonably-priced inputs, operating costs and outlets for the compost.

Status: Large-scale pilot testing

5.2.3.2 UQAR

The University of Quebec at Rimouski proposes producing compost on the farm from wood chips and liquid manure. In certain regions, this process may be of considerable interest.

Since the feasibility of the concept is directly dependent on the availability of high quality absorbents at reasonable cost, its application as a more general solution to the problem of liquid manure surpluses would be difficult. Absorbents are not necessarily found in the same locations as surpluses of liquid manure.

The promoter did not, however, inform the Working Group of the current status of its studies on the process as a whole, or of the technical, environmental and economic results.

Status: Pilot testing

5.2.4 Filtering Marshes

A filtering marsh is a shallow artificial pond in which certain plants are grown. The effectiveness of the marsh is dependent on these plants. During the winter, however, the effectiveness of the marsh drops to a very low level, as plant metabolism slows or even comes to a halt. Given the relatively passive nature of the marsh, the load of effluent discharged into its ponds must be low or the pond must be much larger to maintain the purifying effectiveness of the marsh. In addition, to ensure that nitrogen, phosphorus and other elements do not settle to the bottom of the marsh (saturation), the plants must be harvested to extract this biomass from the marsh.

Raw liquid manure cannot be completely treated through the use of marshes. As a polishing technique, however, this approach is more realistic. Still, the Working Group is not convinced that this technology will be effective, particularly after extended use or over the winter. Filtering marshes raise a number of questions, particularly with respect to the long term. The Working Group feels that a certain amount of information is available in the literature and that a detailed review of the literature on filtering marshes should be undertaken.

Four participants propose marshes as their principal technology: Collège Alfred, Écosphere, KWS Phragmitech and the University of Sherbrooke.

None of these promoters truly look at the management problem as a whole. A number of questions arise. For example: How should the marsh plants be managed? Should they be harvested? How much raw or processed liquid manure can the marsh handle? What can be done with the effluent from the marsh if it fails to meet environmental standards? What is the life expectancy of the marsh (sludge saturation at the bottom)?

The balances submitted by these promoters are incomplete and do not permit objective scientific analysis of the process as a whole. No satisfactory demonstration of the technology has been presented.

Status: Concept definition for liquid hog manure

5.2.5 Use of Bedding

Hog production on bedding involves a number of production techniques. The use of deep biocontrolled bedding itself provides partial treatment of the wastes through relatively intense composting of the bedding on site. The temperature of the bedding can reach 55 °C at a depth of approximately 30 cm. In contrast, the use of shallow or accumulated bedding involves solid manure management techniques without treatment, since the temperature of the bedding on site rarely exceeds 30 or 35 °C. Because of the carbon source provided by the bedding and its aeration (active aeration in the case of biocontrolled bedding and passive aeration for the other techniques), these techniques permit decomposition of the organic matter in the wastes, in part by aerobic processes.

The use of bedding permits reductions of approximately 50% to 75% in the volume of liquid manure and generates farm manure with a higher concentration of nutrient elements and organic matter than liquid manure with a dry matter content of 40%. In addition, with proper maintenance of ambient conditions, it permits significant odour reduction at all stages of manure management, combined with improved livestock comfort. At the same time, however, the use of bedding requires a larger than average building and high investment costs. Operating costs are generally higher than with standard management, essentially as a result of management practices within the building, including more manpower, increased ventilation and heating and the purchase of bedding. Storage and disposal costs, however, are much lower, particularly for management on biocontrolled bedding, which is removed only once a year and spread directly on the field or marketed.

According the research results obtained to date, which have provided the basis for precise agronomic and environmental balances (including gas emissions), these management techniques show interesting potential.

No specific project involving the use of bedding has been evaluated by the Working Group, since none of the files submitted include this approach.

Status: Commercial demonstration

5.3 Chemical Processes

These chemical reactions also generate significant emissions of gases which are harmful to the environment and health, including H₂S (dangerous to health) and ammonia nitrogen (damaging to the environment). In addition, handling the different products on the farm may be extremely dangerous. Consequently, specific precautions must be taken.

Acidification and liming of the solid fraction of liquid manure inhibit the development of the bacteria responsible for odour formation. In addition to stabilizing the solid fraction of the liquid manure, lime amends this organic residue.

5.4 Thermal Processes

This process, combined with granulation, may permit the production of organic fertilizers in pellet or granular form. The efficiency of this process increases with the dry matter content of the liquid manure. However, because of its high requirements in terms of energy and specialized manpower, this type of process cannot be recommended for the treatment of raw liquid manure.

At the same time, this type of treatment may be useful in marketing the residues produced by other types of treatments (solids, sludge, etc.). Since much of the water has been removed, less energy is required to complete the drying process. Costs may be lower.

5.4.1 DEC Group

This complete system, designed for application in a central facility, uses a natural gas or propane burner. In this process, the methane produced during evaporation of the liquid is recovered and burned. This process may be very costly since it involves complete treatment of the raw liquid manure.

Status: Large-scale pilot testing

5.4.2 Progest

The Centre des technologies du gaz naturel proposes Progest, a partial process performed in a central facility. The solid and liquid fractions of the liquid manure are separated on the farm and only the solid fraction is transported to the treatment centre. To be effective, the solid fraction or sludge must have a dry matter content of at least 18%. This process has been used elsewhere in the world but, because of its high energy consumption, it may not be suitable for the treatment of raw liquid manure.

Status: Laboratory testing

5.4.3 Recyc-sol

This process heats liquid manure in a rotary kiln to evaporate the liquids and kill the bacteria present in the dehydrated mixture. This technology is applied in a central facility.

The Working Group feels that this solution may prove costly in view of the energy required. The limited data submitted do not permit detailed analysis.

Status: Concept definition

5.5  Physico-Chemical Processes

5.5.1 Oligolysis

The process of oligolysis is based on electrical treatment by means of metal ions in the liquid manure. The metal ions generated by pairs of copper-carbon, copper-copper or iron-iron electrodes submerged in the liquid manure, on either side of the storage tank, destroy the microorganisms responsible for the creation of objectionable odours.

Oligolysis is thus designed to reduce odours during storage and spreading, without reducing the nutrient value of the liquid manure. The Working Group feels that some clarification is still required on a number of points associated with this technology, including ammonia losses, accumulation of metal ions in the liquid manure, effect on the microflora present in the liquid manure, reliability in terms of odour reduction and cost of utilization.

From the social and technical standpoints, this process may have a certain future, given its effect on odours and the simplicity of the technology. A great deal of work remains to be done on the reliability of the process on environmental and agronomic impacts.

A single promoter, Alfa-Laval’s Oligolyt-G, submitted a process using oligolysis. However, during the course of its study, the Working Group was informed that the promoter has temporarily withdrawn its product from the market because of fluctuations in the effectiveness of this treatment for liquid hog manure.

Status: Commercial demonstration

5.5.2 Settling or Separation using Coagulants and/or Flocculants

These processes use the physical property of separation by settling and the chemical properties of coagulants or flocculants. These promote the formation of molecular chains with the suspended solids, making it easier to separate suspended matter from the liquids. A number of mechanical separation processes use these properties, significantly improving the performance of the equipment.

On the environmental level, it is important to note that residues of some of these products may remain in the effluent or byproducts of the treatment. These must be taken into consideration in determining the ultimate destination of this effluent or these byproducts. The Working Group advocates a cautious approach since no studies have yet been performed on the effect of some of these flocculants on the environment and on crop yields.

No specific project on treatments using flocculants was evaluated by the Working Group, since none of the files submitted include this approach.

5.6 Other

The file proposing yeast cultivation has been classified in this category. A group made up of MD Tech, Laval University, Alpha-Biotech 2000 Inc. and Varisco Canada is working to develop a technology for application at the farm level which consists of cultivating yeasts on a substrate composed of the liquid fraction of liquid manure and whey permeate. These yeasts will be used to replace approximately 20% of the hog feed. The liquid manure is put through vibrating strainers, then mixed with whey and placed in a fermenter. The fermenter is a continuously operating bioreactor with cells mounted on inert supports. The process of yeast cultivation for bioconversion of liquid manure has been specially selected for its capacity to fix ammonia nitrogen and soluble phosphorus under aerobic conditions. Air from the hog barn is fed into the fermenter.

In addition, the availability of whey, which appears to be a vital input, may be a limiting factor in the development of this technology. It is, however, an original process which merits development and observation. The results of current studies will permit more detailed analysis of this approach.

6. CONCLUSIONS

The Working Group feels that it is essential to formulate an approach to the introduction of liquid manure treatment, since no technology can offer the miracle solution to every problem. First of all, the hog producer must assess the problems facing his operation - a surplus of manure and liquid manure in terms of nitrogen and phosphorus, odours, or other factors - and relate them to conditions on both the local and regional levels. In this way, he will be able to identify some of the techniques currently available to minimize the problems before introducing a treatment technology.

6.1 Criteria for Selection and Evaluation of Liquid Manure Management and Treatment Techniques and Technologies in the Quebec Context

In addition, the Working Group used an overall approach in evaluating the treatment technologies in order to avoid creating new problems - of an environmental nature, for example - in attempting to resolve the liquid manure problem. The Working Group thus evaluated the treatment technologies on the basis of a variety of environmental, technical, agronomic, economic and social criteria. (Appendix 2: List of Criteria for the Evaluation of Treatment Processes)

6.2 Existing and New Techniques for Improved Liquid Manure Management

• reducing the use of mineral fertilizers;
• increasing demand from potential recipients of liquid manure;
• exporting surplus organic fertilizers to receiving farms.

6.2.1 Reducing the Nutrient Load of Liquid Manure

Optimal feeding practices offer the greatest improvement in management efficiency. A number of studies indicate that the nutrient load of liquid hog manure can be significantly reduced by modifications to the diet. Nitrogen and phosphorus wastes can be reduced, particularly in the medium term, by 30% each, by increasing the number of feed rations and optimizing them through the incorporation of enzymes or synthetic amino acids. A number of hog farms could thus significantly reduce or even eliminate their liquid manure surpluses without investing in treatment technologies for the livestock concerned. Similarly, improved herd management, genetics, zootechnical performance and environmental control may also assist in achieving this objective.

6.2.2 Reducing Volume

The use of water-saving drinker and feeding systems is recommended for reducing the volumes to be managed and thus permitting savings on storage and spreading. A recent study demonstrates that liquid manure volumes can be reduced by 35% through the use of systems such as drinkers and water-saving drinking bowls (Granger, Cournoyer and Barnett, 1998). Use of this equipment should precede the treatment of liquid manure.

In addition, the installation of roofs on manure storage tanks makes it possible to reduce odours, increase the nitrogen content of liquid manure and reduce volume by preventing the collection of precipitation. These roofs may be flexible or rigid, floating or self-supporting, and constructed of various materials. The economic feasibility of a roof will vary with the distance the liquid manure must be transported for export and spreading and/or with the diameter of the tank. Certain concepts currently under development, particularly for floating or flexible roofs, could permit the construction of economical roofs on pits over 20 metres in diameter. The type of roof to be selected is thus heavily dependent on the diameter of the pit.

The use of bedding also reduces the volumes to be managed, by approximately 50 to 75% in the case of liquid manure.

None of these techniques reduce the load of the liquid manure, and roof construction increases that of nitrogen slightly. They do, however, improve the quality of the product by concentrating the nutrient elements, and thus increasing their value on spreading.

6.2.3 Managing Liquid Manure in Two Fractions: Solid and Liquid

When transportation costs for raw liquid manure are high, it is appropriate to consider the possibility of solid-liquid separation, either by natural settling or through the use of a mechanical separation system. In fact, since the solids in liquid hog manure tend to settle to the bottom of the pit, removal of the upper (more liquid) half from the pit before agitation permits partial separation, which may be of some interest for some farms. The decision to recommend this technique should be made by those responsible for developing the agro-environmental fertilization plan. Separation permits more economical transportation of the liquid manure.

6.2.4. Reducing Odours

The hog industry manages its animal wastes primarily in liquid form. Storage of the liquid manure under anaerobic conditions promotes the development of objectionable odours. As it is spread, the liquid manure is fragmented into droplets, releasing the gases dissolved in it and resulting in a more intense release of odours.

Methods of reducing building and storage odours

• Reduction of wet floor surface areas in buildings.
• Reduction of liquid manure surface area in gutters.
• Reduction of air speed near these surfaces.
• Reduction of dust in building air.
• Creation of windbreaks.
• Modification of feed, to reduce the release of ammonia (NH₃), for example.
• Construction of roofs over manure pits.
• Use of bedding.

Precautions for minimizing odours during spreading

• Use of spray booms with drop pipes and booms with devices for surface incorporation (corn and other row crops).
• Rapid incorporation of liquid manure and manure when possible (ploughing or harrowing immediately after spreading during pre-seeding or post-harvest periods).
• Maintenance of minimum distances between spreading locations and neighbouring residential areas.
• Spreading during periods of no wind or when winds are blowing towards uninhabited areas.
• Spreading on weekdays rather than weekends.
• Use of bedding.

Despite the advantages offered by these alternatives, very few measures have been implemented in Quebec or areas with similar conditions to take advantage of their effectiveness in reducing odours in terms of quantity, intensity, frequency, etc.

6.3 Technologies Currently Known or under Development

It must be noted, however, that the process was voluntary for promoters. As a result, some promoters may not be included in the present report. The Working Group believes, however, that the number omitted is relatively limited.

6.3.1 Observations

The Working Group has made the following observations:

• None of the promoters have demonstrated that their concepts meet the criteria of technical, environmental, agronomic and social performance.
• On the technological level, a number of treatments are at the idea or concept development stage. Few are supported by results from pilot tests. Most offer only projected results for a few parameters.
• The nature and level of the information submitted and/or available do not permit complete, objective scientific analysis.
• Certain concepts are of sufficient interest to justify further development, independently or in combination with others.
• The promoters’ concerns are focused almost exclusively on the treatments themselves. Virtually none of these treatments are presented as part of a complete liquid manure management chain; in this connection, the majority of the treatment technologies are at the concept stage.
• At present, none of the concepts examined permit direct discharge of treated liquid manure into watercourses on an operational basis.
• The effectiveness of liquid manure additives in terms of odour reduction and their environmental safety are unknown.
• Until these technologies are fully developed, a number of techniques or management practices can be implemented, immediately or in the short term (1 to 2 years), to reduce the volumes and nutrient loads to be managed (e.g.: drinkers, reduction of nitrogen and phosphorus through appropriate feeding methods, installation of roofs on liquid manure tanks, etc.).

Consequently:

• Hog farms must make do with existing methods (removal from storage-transportation-spreading) until an appropriate treatment is developed (estimated time: 2 to 5 years).
• Technologies are unlikely to reduce current management costs, particularly in view of the new environmental requirements.
• Continued technological development will require extensive funding (short term).
• Promoters will seek financial support for further development from granting agencies.
• In view of the incomplete information often submitted by promoters, the granting agencies should require the same basic information for analysis of the proposals submitted.
• Information on the progress of the file should be made available to all parties concerned.
• Hog farms can expect high implementation and operating costs for those technologies which prove technically feasible, both on the technological level and to ensure integration in the liquid manure management chain (medium term).

6.4 Areas of Research and Development for Liquid Manure Management and Treatment Technologies

6.4.1 Short Term

The Working Group has identified a number of techniques and processes offering interesting potential in the short term, given their level of development. For instance, optimized feeding practices, water-saving drinker systems, windbreaks, roofs, mechanical separators and bedding are already possibilities. These techniques, together with the processes submitted by the promoters listed in table 3, should be of particular interest to granting agencies interested in projects close to the marketing stage.

6.4.2 Medium and Long Term

The Working Group has also identified a number of other processes offering less clearly demonstrated potential to date, as a result, for example, of less advanced development. These can be considered for the medium- or long-term horizon. Granting agencies interested in the early stages of research (e.g.: laboratory testing, pilot testing) may be more interested in these projects. (Table 4)

6.5 Working Approach for Liquid Manure Additives

7. RECOMMENDATIONS

If the operation is still faced with a surplus, treatment should be considered. Various concepts may be available; here too, the choice will depend on their cost/benefit ratio and respect for the agricultural environment.

7.1 Criteria for Selection and Evaluation of Liquid Manure Management and Treatment Techniques and Technologies in the Quebec Context

• That all agencies involved in the selection of treatment technologies base their decisions on pre-established criteria for each of the technologies to be evaluated.
• That the criteria developed by the Working Group serve as a basis for these agencies.

7.2 Existing and New Techniques for Improved Liquid Manure Management

• That all the existing and available techniques presented in section 6.2 be more widely publicized among hog producers and other participants in the agricultural sector for very short term application.

7.3 Technologies Currently Known or under Development

7.3.1 Follow-up to Observations

The Working Group recommends :

• That hog farmers be advised to make do with existing methods (removal from storage-transportation-spreading) until an appropriate treatment is developed (estimated time: 2 to 5 years).

That granting agencies:

• provide financial support for the concepts identified;
• require the same basic information for further analysis of these files;

since promoters will continue to seek their financial support for further development.

7.3.2 Approach to be Developed for Liquid Manure Treatment

The Working Group recommends :

• That the approach described in sections 6.1 and 6.2 be adopted by all parties concerned.

7.4 Areas of Research and Development for Liquid Manure Management and Treatment Technologies

• For the short term, that the technologies presented in section 6.4.1 be considered as showing interesting potential.
• For the medium and long term, that the technologies presented in section 6.4.2 be considered as showing interesting potential.
• That financial resources be invested in solving the existing problem of liquid manure surpluses.
• That the promoters seek the assistance of agronomic, environmental and economic authorities in developing their projects.
• That the promoters pursue further development of their technologies in the light of the comments contained in this report.
• That all granting agencies assign priority to the development and/or demonstration of complete liquid hog manure treatment technologies.
• That all granting agencies require promoters to consider both the technological aspects of their projects (measurements, factual data, mass balances, etc.) and those relating to the liquid manure management chain at the farm, regional and provincial levels.

That all granting agencies require promoters’ applications for financial aid to include quantifiable projections:

• of the number of farms at the regional and provincial levels on which the proposed technology could be used;
• of the effect of the process on nitrogen, phosphorus, potassium, metals, bacteria, odours (in the building, during storage, on spreading), if applicable on the site of a regional treatment unit, etc.;
• of the quantities of nitrogen, phosphorus, potassium, metals, bacteria, etc. from the byproducts of treatment to be imported and exported at the farm, regional and provincial levels;
• of the management costs of the entire liquid manure management chain as modified by the proposed technology at the farm, regional and provincial levels.

• That all projects provide deliverables permitting verification of each of the projections described above.
• That all granting agencies apply common criteria for project selection and unified monitoring methods.

7.5 Development of a Working Approach for Liquid Manure Additives

• That recognized methods be developed for quantifying odours.
• That methods be developed for assessing the safety of liquid manure additives and their technical effectiveness in reducing odours or in producing the results anticipated by the promoter (conservation of nitrogen, liquefaction, etc.).
• That efforts be made to promote a research program on these developments, since at the present time no methods are unanimously accepted by the scientific community.
• That the Bureau de normalisation du Québec (BNQ) be contacted regarding a feasibility study on the development of a standard for this type of product.
• That proper coordination and adequate, constructive collaboration be established between the BNQ and the investigators who will develop the methodology.

7.6 Distribution of the Report

• agricultural producers;
• organizations offering R&D funding for technological innovations in the area of liquid manure management;
• the promoters who have participated in the evaluation process;
• the relevant provincial and federal departments;
• researchers.

7.7 Follow-up

The Working Group recommends :

That the Fédération des producteurs de porcs du Québec, as the agency responsible for the Agro-Environmental Plan for the Hog Industry, be assigned responsibility for monitoring the recommendations expressed. The "Technological Transfer" Working Group is prepared to assist the Federation in providing follow-up and a framework for the various tests and compilations required to determine their level of development.

REFERENCES

Buelna, G., P. Caouette and S. Pigeon. 1993. Désodorisation des lisiers: Étude comparative des principales technologies existantes à l’aide des bilans et selon une approche intégrée. Sciences et techniques de l’eau. Vol. 26, no. 4, pp. 243-252.

CRIQ, BPR Consultants and Laval University. 1995. Inventaire et étude comparative des technologies de désodorisation et autres méthodes et pratiques d’atténuation des odeurs de lisier, Study performed for the Ministère de l’Environnement et de la Faune, 26 p.

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