Dilute Manure Research Articles

Effects of swine manure dilution with lagoon effluent on microbial communities and odor formation in pit recharge systems

Pit recharge systems (PRS) control odor by managing organic solids in swine manure. However, there needs to be more understanding of PRS's effect on the microbiome composition and its impact on odor formation. A study was conducted to understand how recharge intervals used in PRS impact manure microbiome and odor formation. Bioreactors dynamically loaded simulated recharge intervals of 14, 10, and 4 days by diluting swine manure with lagoon effluent at varying ratios. Treatment ratios tested included 10:0 (control), 7:3 (typical Korean PRS), 5:5 (enhanced PRS #1), and 2:8 (enhanced PRS #2). Manure microbial membership, chemical concentrations, and odorant concentrations were used to identify the interactions between microbiota, manure, and odor. The initial microbial community structure was controlled by dilution ratio and manure barn source material. Firmicutes and Proteobacteria were the dominant microbial phyla in manure and lagoon effluent, respectively, and significantly decreased or increased with dilution. Key microbial species were Clostridium saudiense in manure and Pseudomonas caeni in lagoon effluent. Percentages of these species declined by 8.9% or increased by 17.6%, respectively, with each unit dilution. Microbial community composition was controlled by both treatment (i.e., manure dilution ratio and barn source material) and environmental factors (i.e., solids and pH). Microbiome composition was correlated with manure odor formation profiles, but this effect was inseparable from environmental factors, which explained over 75% of the variance in odor profiles. Consequently, monitoring solids and pH in recharge waters will significantly impact odor control in PRS.

Model Adaptation and Validation for Estimating Methane and Ammonia Emissions from Fattening Pig Houses: Effect of Manure Management System.

This paper describes a model for the prediction of methane and ammonia emissions from fattening pig houses. This model was validated with continuous and discrete measurements using a reference method from two manure management systems (MMS): long storage (LS) in deep pits and short storage (SS) by daily flushing of a shallow pit with sloped walls and partial manure dilution. The average calculated methane and ammonia emissions corresponded well with the measured values. Based on the calculated and measured results, the average calculated CH4 emission (18.5 and 4.3 kg yr-1 per pig place) was in between the means from the continuous data from sensors (15.9 and 5.6 kg yr-1 per pig place) and the means from the discrete measurements using the reference method (22.0 and 3.1 kg yr-1 per pig place) for the LS and SS systems, respectively. The average calculated NH3 emission (2.6 and 1.4 kg yr-1 per pig place) corresponded well with the continuous data (2.6 and 1.2 kg yr-1 per pig place) and the discrete measurements using the reference method (2.7 and 1.0 kg yr-1 per pig place) from LS and SS, respectively. This model was able to predict the reduction potential for methane and ammonia emissions by the application of mitigation options. Furthermore, this model can be utilized as a predictive tool, enabling timely actions to be taken based on the emission prediction. The upgraded model with robust calculation rules, extensive validations, and a simplified interface can be a useful tool to assess the current situation and the impact of mitigation measures at the farm level.

Peering into a Simplified Digestor for Households: Performance, Cost and Carbon-Neutral Niche

In this study, a black-shading cylindrical water tank made of high-density polyethylene was locally manufactured as a household digestor for treating cow manure in Bangladesh. Effluent slurry instead of water was reused for manure dilution under manure-to-slurry ratios of 1:2 and 1:1, to assess this small prototype’s production efficiency and feasibility. The specific biogas production at both ratios matched well, by 0.12 m3/kg VS and 0.14 m3/kg VS, respectively, while the former slurry dilution operation outperformed in daily and accumulative biogas production by 16% and 57%, correspondingly, referring to 0.49 Nm3/d on average and 8.55 Nm3 in total, potentially meeting a 2 h household cooking energy requirement. From a nationwide viewpoint, slurry dilution was proven to be a great initiative to conserve water amounting to 50,286,751 m3 for 114,810 households of 6 person-equivalents annually, while cutting chemical costs by USD 32,720,684/yr and trimming annual greenhouse gas emission by 1.8 million tons of CO2e. This study revealed that a small prototype digestor could be an alternative energy source for cost-effective and eco-friendly household applications.

Resource recovery for environmental management of dilute livestock manure using a solid-liquid separation approach

Mechanical solid-liquid separation is an emerging closed-loop technology to recover and recycle carbon, nutrients and water from dilute livestock manure. This closed-loop concept is tested using a modular separation technology (Z-Filter) applied at full-scale for the first time to treat effluent from a pasture-based dairy. Effluent flow rates were 200–400 L min−1 at a total solids (TS) content of 0.52% (pH 7.2). Separation efficiency and composition of the separated solid fraction were determined, and chemically-assisted separation with cationic polymer flocculant with/without hydrated lime was also tested. Without flocculant and lime, 25.9% of TS and 33.4% of volatile solids (VS) ended up in the solid fraction, but total Kjeldahl nitrogen (TKN), phosphorus (P) and potassium recovery was not significant, likely being in poorly separable fine particle or soluble fractions. With a 5% flow-based dosage of flocculant, most of the TS (69%) and VS (85%), and notable amounts of TKN (52–56%) and P (40%) ended up in the solid fraction. Phosphorus recovery was further increased to 91% when both flocculant and hydrated lime was added up to pH 9.2. The solid fraction was stackable with 16–20% TS, making transport more economical to enable further processing and beneficial reuse of nutrients and organic matter. Removal of VS also reduces fugitive methane emissions from uncovered anaerobic effluent ponds. Overall, the results indicated that solid-liquid separation could provide improved environmental management options for dairy farmers with dilute manure effluent to beneficially utilise organic matter and nutrients.

Swine manure dilution with lagoon effluent impact on odor reduction and manure digestion.

Manure management systems have a major impact on odor from swine operations. A study was conducted to compare deep-pit manure management systems to flushing barn manure management systems for odor reduction and organic matter degradation. Bioreactors were used to mimic manure management systems in which manure and lagoon effluent were loaded initially, and subsequent manure was added daily at 5% of its storage capacity (1 L). Final manure-to-lagoon effluent ratios were 10:0 (deep-pit manure management system), 7:3 (Korean flushing systems), 5:5 (enhanced flushing systems), and 2:8 (enhanced flushing systems). At the end of the trial, at 4 (2:8), 10 (5:5), or 14 (10:0, 7:3) d, manure and gas concentrations of odorants were measured, including total solids (TS), total N (TN), and total C (TC) of manure. Odor was evaluated using the odor activity values (OAVs), and regression analysis was used to determine the effects of dilution and TS on manure properties and OAVs. Solids in the manure were positively correlated to TN, TC, straight chain fatty acids (SCFAs), branch chain fatty acids (BCFAs), total phenols, and total indoles and positively correlated to OAV for SCFAs, BCFAs, ammonia, total phenols, and total indoles. Reducing TS by 90% reduced BCFA, ammonia, phenols, and indoles by equal amounts in air. Carbon dioxide was the main C source evolved, averaging over 90%, and CH4 increased with dilution quadratically. Overall, reducing solids in manure by dilution had the biggest impact on reducing odor and increasing organic C degradation.

Method of biological treatment of agricultural waste by microbial synthesis

Traditional manure management is unacceptable for dilute manure, the share of which in the structure of organic waste from livestock farms and complexes is continually increasing. The approach is relevant, at the first stage of implementation, it is necessary to create the supply base for non-conventional energy using, including organic biomass energy (manure, crop waste, etc.). Also, the problem of waste utilization is closely linked to another environment protection, which requires intensive recycling of animal agriculture. It requires necessary to search reclamation methods that would ensure the utilization of agrotechnical, energetic, feed, and other properties. The article presents the treatment process of manure utilization by microbial synthesis.

Bio Gas Plant Green Energy From Poultry Wastes In Singapore

Singapore is a land scarce nation where farming space is very limited competing with other critical uses for a growing population. Farms taking up large tract of land and generate wastes face many unsurmountable difficulties and regulatory compliances on sustainability issues. Poultry farm is not the best type of industry due to polluted wastes generated and foul smell emissions. Yet an 800,000 chicken egg-producing farm in the last bastion of farming land in Singapore called Lim Chu Kang has evolved to overcome the space constraints, environmental regulatory, sustainability demands, production efficiencies and green energy push in lowering the carbon footprint. This company has been the first successful farm in Singapore to convert chicken wastes into biogas as fuel to generate electricity. In doing so, it has reduced the polluted wastes and transform it into energy toward self-sufficiency, recovering waste heat from the turbine exhaust for drying of chicken feed. The power generated is up to 1 MW while the waste water in the aerobic digester is treated and extracted the sludge into dried cake for agricultural fertilizers. Excess energy could also be sold to the Singapore Power Grid as income. This company in its CSR efforts has invested this waste-to-green energy technology as a creative first mover while increasing food security, fighting food scarcity promoting safe eggs for the people of Singapore. Further initiatives on achieving international green energy recognition and improving on green energy efficiencies would be the steps forward for the benefits of Singapore. Green energy production is an essential way of meeting energy needs as the inevitable depletion of non-renewable energy sources coupled with climate change are now global challenges. It adopted a zero-waste policy to reduce its waste stream and air pollution with an anaerobic digester and a biogas power plant fuelled by 50 tonnes of chicken manure per day. The biogas is used to generate heat and electricity power the farm’s infrastructure, including its new co-generation feed dryer. The digester liquor is treated and treated water is recycled for the initial dilution of manure to enhance the digestion process. Sludge undergoes a belt press to separate solids and liquid resulting in bio solid cake used for making fertilisers. This integrated system ensures that by-products can be reused, minimizing waste and reducing emission of greenhouse gases by adapting biogas for green electricity production.

Inexpensive In-Field Manure Solids Tester

Abstract. Manure losses from crop fields via surface and subsurface pathways following land application can lead to eutrophication and habitat destruction in surface waters. High solids manure has less susceptibility to runoff and leaching, which is particularly important in high risk fields with increased loss potential. Unfortunately, the determination of manure solids content is typically conducted by laboratory analysis where results are provided after field application has occurred. An inexpensive solids tester (less than $40 to construct) was developed out of readily available materials for manure applicators to determine the solids content of liquid dairy manure in-field and in real time prior to application. As manure samples are passed through the screen, solids are captured on the screen while more dilute manure passes through. In order to evaluate the solids tester, 33 manure samples were collected from 6 separate dairies with a variety of bedding types (3 farms used sand and 3 farms used recycled digested solids for bedding) and manure handling and processing systems. Results indicated that the manure volume that is retained on the screen can be related to the solids content of dairy manure from 3% to 9%. An equation was produced to relate manure solids to the volume retained on the screen, TS=1.7953e 0.0046Vr , with an r-squared value of 0.82. Manure samples with less than 3% solids were shown to pass through the screen completely, therefore results were inaccurate for low TS content. The results did not vary significantly for dairies which used sand bedding and those that used recycled manure solids. This quick in-field measurement of total solids content allows for application to appropriate fields, thus reducing the risk of manure losses to nearby waterways.

Solid thickening and methane production of livestock wastewater using dissolved carbon dioxide flotation

Dilute manure is classified as wastewater due to the large quantity of water used in livestock production in Korea. Livestock wastewater treatment is required in order to reduce high moisture content and treat fluids discharged from the digestion process. In livestock wastewater treatment plants, large quantities of CO2 gas are produced at combined heat and power facilities as well as in the anaerobic digestion (AD) process. This gas produced during livestock wastewater treatment can be used as a separator of solids from liquid in wastewater. In this study, a flotation system using recycled CO2 gas was used for sludge thickening. An anaerobic toxicity assay (ATA) and a biochemical methane potential assay were used to assess the toxicity impact of recycling CO2 on the methane production potential. ATA experiments confirmed that CO2 toxicity did not impair the AD process. The tests indicated that the cumulative methane yield from influent livestock manure enriched with CO2 was approximately 190 mL-CH4/g-VSadded. The data demonstrated the potential of using dissolved CO2 flotation in the AD of diluted livestock wastewater.

Lab-assay for estimating methane emissions from deep-pit swine manure storages

Methane emission is an important tool in the evaluation of manure management systems due to the potential impact it has on global climate change. Field procedures used for estimating methane emission rates require expensive equipment, are time consuming, and highly variable between farms. The purpose of this paper is to report a simple laboratory procedure for estimating methane emission from stored manure. The test developed was termed a methane production rate (MPR) assay as it provides a short-term biogas production measurement. The MPR assay incubation time is short (3d), requires no sample preparation in terms of inoculation or dilution of manure, is incubated at room temperature, and the manure is kept stationary. These conditions allow for high throughput of samples and were chosen to replicate the conditions within deep-pit manure storages. In brief, an unaltered aliquot of manure was incubated at room temperature for a three-days to assay the current rate of methane being generated by the manure. The results from this assay predict an average methane emission factor of 12.2 ± 8.1 kg CH4 head−1 yr−1 per year, or about 5.5 ± 3.7 kg CH4 per finished animal, both of which compare well to literature values of 5.5 ± 1.1 kg CH4 per finished pig for deep-pit systems (Liu et al., 2013). The average methane flux across all sites and months was estimated to be 22 ± 17 mg CH4 m−2-min−1, which is within literature values for deep-pit systems ranging from 0.24 to 63 mg CH4 m−2-min−1 (Park et al., 2006) and similar to the 15 mg CH4 m−2-min−1 estimated by (Zahn et al., 2001).

The Impact of Dry Mass Content in Pig Liquid Manure on its Treatment with a Filtration Method

Abstract The present study examines the impacts of dry mass content in pig liquid manure on its treatment with a filtration method. Samples of liquid manure with variable dry mass content were subjected to treatment using phosphoric acid, sulfuric acid, lime milk and superphosphate, as well as to thermal treatment, while in the last phase of pressure filtration. Increased dilution of the manure resulted in a reduced raw materials consumption ratio and improved filtration process efficiency, which ranged from 408 to 3765 kg/m2/h. The highest filtration efficiency was achieved using manure containing 3% dry mass, while the lowest efficiency was observed in manure at 10% dry mass. The increase in liquid manure dilution also reduced chemical oxygen demand in the filtrate, which ranged from 15 062 to 3656 mg/l. An appropriate manure dilution level, under the constant parameters of the treatment process, reduced phosphorus content in the filtrate to < 10 mg/kg while simultaneously enriching the post-filtration sediment with this precious fertilizing component.

Aplicação de efluente tratado de suinocultura para diluição de dejeto suíno e remoção de nitrogênio por desnitrificação

Este trabalho avaliou o efeito da diluição do dejeto de suíno com o efluente tratado a 50% (v/v), com vistas a aumentar a desnitrificação via fornecimento de carbono ao processo. Considerando-se a diluição estudada, a concentração média de N-NO3- na mistura foi de 47,9 + 14,5 mg L-1, e a DQO da mistura, na faixa de 17.543 + 675 mg L-1, resultando numa relação DQO/N-NO3- de 366, extremamente favorável à ocorrência da atividade desnitrificante no tanque de homogeneização da mistura. A concentração de N-NO3- foi reduzida biologicamente a 0,5 mg L-1 (cerca de 1% da concentração inicial). O procedimento testado promoveu, ainda, uma melhora na etapa de separação sólido-líquido, empregando coagulantes naturais, onde foi observado um consumo de tanino inferior ao esperado.

Effect of swine manure dilution on ammonia, hydrogen sulfide, carbon dioxide, and sulfur dioxide releases

Animal manure is a significant source of environmental pollution and manure dilution in barn cleaning and slurry storage is a common practice in animal agriculture. The effect of swine manure dilution on releases of four pollutant gases was studied in a 30-day experiment using eight manure reactors divided into two groups. One group was treated with swine manure of 6.71% dry matter and another with manure diluted with water to 3.73% dry matter. Ammonia release from the diluted manure was 3.32 mg min −1 m −2 and was 71.0% of the 4.67 mg min −1 m −2 from the undiluted manure ( P < 0.01). Because the ammonia release reduction ratio was lower than the manure dilution ratio, dilution could increase the total ammonia emissions from swine manure, especially in lagoons with large liquid surface areas. Carbon dioxide release of 87.3 mg min −1 m −2 from the diluted manure was 56.4% of the 154.8 mg min −1 m −2 from the undiluted manure ( P < 0.01). Manure dry matter was an important factor for carbon dioxide release from manure. No differences were observed between the treatments ( P > 0.05) for both hydrogen sulfide and sulfur dioxide releases. Therefore, dilution could also significantly increase the total releases of hydrogen sulfide and sulfur dioxide to the environment because dilution adds to the total manure volume and usually also increases the total gas release surface area.

Effects of Polymer Charge Density and Molecular Weight on Flocculation Treatment of Swine Manure at Various Dry Matter Contents

This study investigated the effects of polymer charge density (CD) and molecular weight (MW) on the efficiency of solid-liquid separation of swine manure at various dry matter (DM) contents. Flocculated manures were filtered through 1 mm screens. The dose of high MW polymers required for optimum suspended solids (SS) removal increased with increasing CD. At manure DM content ranging from 29 to 90 g L-1, optimum dose averaged 22, 29, 63, and 85 mg L-1 with the 2%, 10%, 35%, and 55% CD polymers, respectively. Chemical cost (in U.S. dollars) was estimated at $0.12, $0.18, $0.47, and $0.69 per m3 of manure for the four polymers, respectively. However, maximum SS and P reductions tended to increase with increasing CD and averaged 84%, 89%, 94%, and 95% for SS and 62%, 67%, 70%, and 71% for P with the 2%, 10%, 35%, and 55% CD polymers, respectively. High MW polymers required lower doses and were more efficient in terms of SS and P removals than medium MW polymers, while similar results were obtained with high and very high MW polymers. Results suggested that bridging was the main mechanism involved in manure flocculation, but high SS removal required the bridging as well as the charge neutralization effect of high CD polymers. There was no consistent correlation between optimum dose and manure DM content between 29 and 106 g L-1 for the 10% and 35% CD, high MW polymers. Manure dilution at the farm would thus increase cost because of higher polymer requirements and the need for equipments able to handle larger volumes.

Behaviour of 14C-sulfadiazine and 14C-difloxacin during manure storage

The persistence of sulfadiazine, difloxacin, and their metabolites has been investigated in stored manure. The manure collected from sulfadiazine ( 14C-SDZ) and difloxacin ( 14C-DIF) treated pigs contained N-acetylsulfadiazine (Ac-SDZ), 4-hydroxy-SDZ (4-OH-SDZ), and sarafloxacin (SARA) as the main metabolites, respectively along with their parent compounds. Manures were stored separately at 10 °C and 20 °C at various moisture levels. About 96–99% of the radioactivity remained in extractable parent compounds and their metabolites after 150 d of storage. The formation of non-extractable residue and the rate of mineralization were both negligible in manure containing SDZ and DIF. During storage SDZ concentration increased as a result of the deacetylation of Ac-SDZ, whose concentration decreased proportionally. Hence the environmental effects may be underestimated if the parent compound alone is considered for environmental risk assessment. About 11% and 14% of 4-OH-SDZ were lost after 20 and 40 d of storage; thereafter its concentration increased relatively, highlighting hydroxylation of SDZ. DIF degraded very slowly (7% loss after 150 d) during the storage of manure; in contrast the concentration of SARA decreased rapidly (72–90% loss after 150 d). Dilution of manure and storage at higher temperatures for a reasonable period of time enhanced the rate of reactions of SDZ, DIF and their related metabolites.

Effects of cycle-frequency and temperature on the performance of anaerobic sequencing batch reactors (ASBRs) treating swine waste

Anaerobic digestion of animal waste is a technically viable process for the abatement of adverse environmental impacts caused by animal wastes; however, widespread acceptance has been plagued by poor economics. This situation is dismal if the technology is adapted for treating low strength animal slurries because of large digester-volume requirements and a corresponding high energy input. A possible technology to address these constraints is the anaerobic sequencing batch reactor (ASBR). The ASBR technology has demonstrated remarkable potential to improve the economics of treating dilute animal waste effluents. This paper presents preliminary data on the effects of temperature and frequency-cycle on the operation of an ASBR at a fixed hydraulic retention time (HRT). The results suggest that within the parameter range under consideration, temperature did not affect the biogas yield significantly, however, higher cycle-frequency had a negative effect. The biogas quality (%CH 4) was not significantly affected by temperature nor by the cycle-frequency. The operating principle of the ASBR follows four phases: feed, react, settle, and decant in a cyclic mode. To improve the biogas production in an ASBR, one long react-phase was preferable compared to three shorter react-phases. Treatment of dilute manure slurries in an ASBR at 20 °C was more effective than at 35 °C; similarly more bio-stable effluents were obtained at low cycle-frequency. The treatment of dilute swine slurries in an ASBR at the lower temperature (20 °C) and lower cycle-frequency is, therefore, recommended for the bio-stabilization of dilute swine wastewaters. The results also indicate that significantly higher VFA degradation occurred at 20 °C than at 35 °C, suggesting that the treatment of dilute swine slurries in ASBRs for odor control might be more favorable at the lower than at the higher temperatures examined in this study. Volatile fatty acid reduction at the two reactor temperatures and cycle-frequencies, from a high of 639 ± 75 mg/L to a low of 92 ± 23 mg/L, greatly reduced the odor and the odor-generation potential in post-treatment storage. The nutrients (both N and P) in the waste influent were conserved in the effluents.

Effect of Bovine Manure onCryptosporidium parvumOocyst Attachment to Soil

The objective of this work was to assess the effect of dilute bovine manure (1.0% and 0.1%) versus that of no manure on attachment and subsequent detachment of Cryptosporidium parvum oocysts to soil. Manure enhanced the attachment of oocysts to soil particles; the maximum attachment was observed with 0.1% manure. Oocyst attachment was partially reversible; maximum detachment was observed with dilute manure. These results indicate that oocyst attachment to soil is substantially affected by bovine manure in a complex manner and should have implications for how oocysts may be transported through or over soils.

EFFECTS OF ENVIRONMENTAL FACTORS ON ODOR EMISSION FROM PIG MANURE

Altering environmental factors may change odor emission from pig manure. The main objective of thislaboratory-scale study was to examine the effects of temperature, ventilation rate, emitting area, and manure dilution ratioon odor emission from growing pig manure, while also testing their effects on manure characteristics. Manure was placedin vessels with different surfaces (303, 475, and 595 cm2), and water was added to create different dilution ratios (0%, 50%,and 100%). The vessels were connected to glass capillaries with different ventilation rates through the headspace (0.5, 1.0,and 1.5 L min-1) and were placed in climate-controlled rooms with different temperatures (10C, 20C, and 30C). We useda face-centered central composite design with 54 experimental units in two rounds of three blocks. Odor samples were takenat the end of experiment (after seven days). Manure samples were collected at the start and at the end of the experiment. Themean odor emission from the manure vessel was 2326 ouE h-1 m-2. Increased temperature, ventilation rate, and dilution ratioincreased odor emission. Emitting area did not influence odor emission, but positively influenced total-N loss. Total-N lossincreased as temperature and ventilation rate increased, but decreased as dilution ratio increased. Lowering temperature andventilation rate can be considered as starting points to reduce odor emission from pig manure in practical conditions. Theeffects of dilution ratio and emitting area on odor emission could not be fully separated from the effect of headspace volumein this study and should be further studied.

Effect of poultry diet on phosphorus in runoff from soils amended with poultry manure and compost.

Phosphorus in runoff from fields where poultry litter is surface-applied is an environmental concern. We investigated the effect of adding phytase and reducing supplemental P in poultry diets and composting poultry manures, with and without Fe and Al amendments, on P in manures, composts, and runoff. We used four diets: normal (no phytase) with 0.4% supplemental P, normal + phytase, phytase + 0.3% P, and phytase + 0.2% P. Adding phytase and decreasing supplemental P in diets reduced total P but increased water-extractable P in manure. Compared with manures, composting reduced both total P, due to dilution of manure with woodchips and straw, and water-extractable P, but beyond a dilution effect so that the ratio of water-extractable P to total P was less in compost than manure. Adding Fe and Al during composting did not consistently change total P or water-extractable P. Manures and composts were surface-applied to soil boxes at a rate of 50 kg total P ha(-1) and subjected to simulated rainfall, with runoff collected for 30 min. For manures, phytase and decreased P in diets had no significant effect on total P or molybdate-reactive P loads (kg ha(-1)) in runoff. Composting reduced total P and molybdate-reactive P loads in runoff, and adding Fe and Al to compost reduced total P but not molybdate-reactive P loads in runoff. Molybdate-reactive P in runoff (mg box(-1)) was well correlated to water-extractable P applied to boxes (mg box(-1)) in manures and composts. Therefore, the final environmental impact of dietary phytase will depend on the management of poultry diets, manure, and farm-scale P balances.

Treatment of Dilute Manure Wastewaters by Chemical Coagulation

Results from laboratory coagulation-settling experiments using five coagulants (one inorganic salt and four organic polymers) on four dilute wastewaters (fresh manure from swine, poultry, and cattle and effluent from a swine anaerobic digester) are presented to provide chemical coagulation data for designing treatment facilities for livestock and poultry. Adjustment of pH alone was generally ineffective in promoting coagulation on all wastewaters. Values of pH above nine were effective for swine wastewater. Ferric chloride removed 60 to 70% of the volatile solids (VS) for cattle and swine at concentrations of 300 to 450 mg/L, but was less effective on poultry wastewater. Addition of organic polymers with iron salt did not improve coagulation from swine wastewater. Synthetic polymers and chitosan were excellent coagulants for all manure wastewaters but not for digester effluent. Based upon the effective concentrations to remove suspended solids from the flush waters of a 1,000-head swine finishing unit, synthetic polymers are the most cost-effective chemical coagulant, while chitosan is the least cost-effective.