Dairy Cattle Waste Research Articles

Virulence profile of Candida spp. isolated from an anaerobic biodigester supplied with dairy cattle waste

Anaerobic biodigesters play a crucial role in enhancing animal waste management. However, the presence of pathogens in the biodigestion process poses a significant concern. Candida spp., a widespread fungus known for its opportunistic nature and adaptability to diverse environmental conditions, including reciprocal transmission between humans and animals, is one such pathogen of concern. Therefore, it is imperative to assess the virulence profile of Candida spp. originating from anaerobic biodigestion processes. Here we demonstrate that strains isolated from the biodigestion process of dairy cattle waste exhibit noteworthy virulence mechanisms, surpassing the virulence of clinical control strains. After we identified strains from affluent, effluent, and biofertilizer, we observed that all analyzed isolates produced biofilm. Additionally, a substantial proportion of these isolates demonstrated phospholipase production, while only a few strains exhibited protease production. Furthermore, all strains exhibited resistance or dose-dependent responses to amphotericin B and itraconazole, with the majority displaying resistance to fluconazole. In the in vivo test, we observed a significant correlation (p < 0.05) between the LT50 and biofilm formation as well as hyphae/pseudohyphae production. Additionally, some isolates demonstrated a quicker nematode-killing capacity compared to clinical controls. Our findings underscore the considerable pathogenic potential of certain Candida species present in the dynamics of anaerobic biodigestion. Importantly, the anaerobic biodigester system did not eliminate Candida strains from dairy cattle waste, highlighting the need for caution in utilizing biodigester products. We advocate for further studies to explore the virulence of other microorganisms in various animal production contexts. Furthermore, our results emphasize the urgency of enhancing waste treatment methods to effectively eliminate pathogens and curb their potential dissemination.

Dynamic System Modeling and Sustainability Strategies for Circular Economy-Based Dairy Cow Waste Management

Dairy farming activities produce waste that can have a negative impact on the environment. The processing of livestock waste will reduce pollution and support environmental conservation programs that are currently being intensified by the West Java Provincial Government, Indonesia. An economic approach that can minimize waste and maximize resources is the circular economy (CE) approach. CE can occur at the macro-, meso-, or microlevels. The application of micro-scale CE can be carried out in a business activity. One of the micro business groups that have implemented the CE concept in Bandung Regency, West Java Province, Indonesia, is the Taruna Mukti Farmer Group, which is located in the Citarum River sub-basin area. From 2008 to 2022, this group processed 49,580 tons of cow dung into organic fertilizer. However, there has been a decline in livestock waste processing, where production reduced from 3700 tons in 2018 to 1280 tons in 2021, then to only 500 tons in 2022. Therefore, this study aims to design a sustainable strategy for livestock waste management based on CE in the Taruna Mukti Farmer Group. The method used is in-depth interviews with the Drivers, Pressure, State, Impact, Response (DPSIR) approach. In addition, this study will also describe the CE model in the management of dairy cattle waste. Key Informants come from the Farmer Group and related stakeholders. Based on the results of the study, it is known that the dairy cattle waste management model in the Taruna Mukti Farmer Group is a form of implementing the CE concept with a circular flow of material and involving various stakeholders and an extensive marketing network. With the current conditions, the simulation results of processing livestock waste into organic fertilizer show a decline/unsustainability. To support the sustainability of livestock waste management, a response is needed in the form of strengthening the internal management of the Farmer Group’s organization, regular assistance and supervision from the local government and non-government organizations, and guidance regarding the marketing of organic fertilizers and ease of access to markets.

Reducing soluble lead and cadmium in contaminated soils using dairy cattle waste based vermicompost

Continuous use of synthetic fertilizer can lead to the accumulation of heavy metals in the soil. The use of organic amendment can reduce the solubility of heavy metals such as Pb and Cd in soil. The experiment was undertaken to determine the decline of soluble Pb and Cd in polluted soils treated with dairy cattle waste-based vermicompost. The study used two soil samples; Inceptisols collected from Air Duku Village and Entisol from Beringin Raya Village, Bengkulu, Indonesia. Entisols and Inceptisols contained 2.0 and 0.4 mg kg-1 soluble Pb and 0.7 and 0.8 mg kg-1soluble Cd, respectively. The samples were pretreated with either 100 ppm Pb or Cd. Vermicompost was applied at the rate of 0, 10, 20, and 30 Mg ha-1 on samples of Inceptisols and Entisol, arranged in Completely Randomized Design (CRD). The mixture was incubated for eight weeks. After the incubation ended, the soil sample was analyzed for soluble Pb and Cd using DTPA extraction before detection using Atomic Absorption Spectroscopy. The study resulted that the soluble Pb and Cd significantly reduced with vermicompost treatment, being the lowest was at the rate of 30 Mg ha-1. Furthermore, the decreased soluble Pb and Cd was more substantial in Inceptisols than Entisols. Soluble Pb in both soils was lower than Cd, suggesting a higher retention affinity of the former. This study summarizes that vermicompost at the rate of 30 Mg ha-1 effectively immobilizes Pb and Cd in contaminated soils.

Biogas as methane mitigation path on dairy cattle waste management

Greenhouse gas (GHG) caused global warming. The GHG emissions in ruminants come from enteric fermentation and manure management. Some of manure management of large ruminants (dairy cattle and beef cattle) are Biogas and manure stacking. Biogas in manure management is the most suggested, since beside reduce the GHG emission, it’s also produced an alternative energy source. Biogas system had been applied by many sectors including small holder farmers. There is no data available on the reduction value of GHG emission resulted from Biogas system. Therefore, the equation of methane mitigation from biogas was needed to predict the potential mitigation from this activity. This study aimed to create a simple equation to predict methane mitigation from manure management activity of dairy cattle, also to predict added value as an energy source in manure management. A correction factor of emission from dry stacking of manure compared to emission from biogas is also required in the calculation. Equations formed from the study are EB=(940,57 CO2-eq/AU/year) x N, EBB=130,73 CO2-eq/AU/year x N, and EDS=0,659281 x EB or EDS=4,74336 x EBB. These equations used to predict greenhouse gas production in the manure of dairy cattle. The final result showed that manure management of dairy cattle should be done by using Biogas. Gases produced in biogas can be used as alternative energy by burning it and contribute to reducing the GHG production in manure management.

Manure Flushing vs. Scraping in Dairy Freestall Lanes Reduces Gaseous Emissions

The objective of the present study was to mitigate ammonia (NH3), greenhouse gases (GHGs), and other air pollutants from lactating dairy cattle waste using different freestall management techniques. For the present study, cows were housed in an environmental chamber from which waste was removed by either flushing or scraping at two different frequencies. The four treatments used were (1) flushing three times a day (F3), (2) flushing six times a day (F6), (3) scraping three times a day (S3), and (4) scraping six times a day (S6). Flushing freestall lanes to remove manure while cows are out of the barn during milking is an industry standard in California. Gas emissions were measured with a mobile agricultural air quality lab connected to the environmental chamber. Ammonia and hydrogen sulfide (H2S) emissions were decreased (p &lt; 0.001 and p &lt; 0.05) in the flushing vs. scraping treatments, respectively. Scraping increased NH3 emissions by 175 and 152% for S3 and S6, respectively vs. F3. Ethanol (EtOH) emissions were increased (p &lt; 0.001) when the frequency of either scraping or flushing was increased from 3 to 6 times but were similar between scraping and flushing treatments. Methane emissions for the F3 vs. other treatments, were decreased (p &lt; 0.001). Removal of dairy manure by scraping has the potential to increase gaseous emissions such as NH3 and GHGs.

Co-digestion of Dairy Cattle Waste in a Pilot-Scale Thermophilic Digester Adapted to Poultry Litter Feedstock: Stress, Recovery, and Microbiome Response

The adaptability of a thermophilic anaerobic digester stabilized long-term with poultry litter as sole feedstock was measured with regard to co-digestion with dairy cattle manure. Both feedstocks have low C/N ratios but differ in carbohydrates, protein, and fiber content. The digester was a pilot-scale (40 m3) sCSTR (semi-continuously stirred tank reactor) with a 20-day hydraulic retention time (HRT). Dairy manure was added as three step-wise increases in concentration: 20, 40, and 80%. At 20% dairy manure, methane production was unchanged (17–19 m3 day−1). But as the fraction of dairy manure increased, methane, ammonia, sCOD, acetate, and propionate decreased. At 80% dairy manure, methane volume dropped by 60%. Acetate concentration decreased from an initial 878 ± 209 mg L−1 during poultry litter mono-digestion to 285 ± 169 mg L−1 with 80% dairy manure. Upon returning to mono-digestion, methane production was on a trajectory of recovery although acetate remained low. Bacterial community structure shifted during co-digestion, but community resilience was also underway following return to the original feedstock for one HRT. The dominant bacterial phylotypes belonged to the groups Thermotogales, Synergistales, Clostridiales, and Halanaerobiales, and three uncharacterized orders (MBA08, SHA-98, OPB54) in class Clostridia. Co-digestion led to a shift in dominance with reductions in Thermotogales and OPB54, and an increase in MBA08. This experiment provides guidance for digester operators who wish to mix livestock and poultry manures for thermophilic co-digestion.

Quality of Enriched Liquid Organic Fertilizer from Dairy Cattle Wastes on Closed Agriculture System

Liquid organic fertilizer (LOF) supplementation for solid organic fertilizer can accelerate the availability of plant nutrients. However, the nutrient content of LOF is highly dependent on its sources. The objective of the experiment was to examine the nutrient content of enriched liquid organic fertilizer from dairy cattle wastes. The experiment was conducted at Closed Agriculture Production System Research Station located in Air Duku Village, Bengkulu, Indonesia, at 1054 m above sea level. The experiment was laid out in a Completely Randomized Design with ten treatments and three replications. The treatments consisted of LOF from dairy cattle wastes enriched with Tithonia diversifolia, Ageratum conyzoides, Leucaena leucocephala, and Gliricidia sepium, their combination with phosphate rock, the combination of Tithonia diversifolia, and Ageratum conyzoides, and control. The LOF solution was anaerobically incubated for six weeks. The experiment indicated that during the incubation, solution pH declined for the first two weeks, gradually increased up to week 6. At the end of incubation, control exhibited the highest pH as compared to those with enrichment, indicating that decomposition of green biomass released a considerable amount of hydrogen. Enrichment of LOF considerably increased the contents of C, N, P, K, Ca, and Mg. The addition of phosphate rock to biomasses did not contribute a prominent increase in phosphorus content, possibly due to its low solubility at high pH. LOF enrichment with Tithonia diversifolia and Ageratum conyzoides had the highest N, P, and Mg contents. Therefore, the enrichment is the most potential for LOF production in closed agriculture system.

Waste Management in Dairy Cattle Farms in Aydın Region. Potential of Energy Application

In this paper, the dairy cattle waste management systems on farms in Aydın region in Turkey were investigated. Number of farms and livestock herd size, type of barn, type of machinery and farm labour force were studied. The collection, management and storage systems of manure produced in dairy cattle farms were taken into consideration. Additionally, biogas amount, which is produced from animal waste, was calculated for all districts of Aydın by using the number of livestock animals and various criteria such as the rate of dry matter. Results show that the typical and representative farm in the Aydın region is facility with a total head over 100 heads. 89.6% of the farms have heads in the range of 100 to 200. The amount of biogas that can be produced from all manure collected in Aydın region in the biogas plants is approximately 160,438 m3/day (based on 0.5 m3/day biogas per cattle), which would produce around 100 GWh/year that can be used for own needs of farms owners.

Potential Utilization of Dairy Cattle Waste into Biogas (Jetak Village, Semarang City, Central Java)

This study aims to identify the potential of dairy cattle waste to become biogas in Jetak Village as a solution in dealing with environmental problems. In this study using primary data obtained from 72 respondents through in-depth interviews, observation and documentation. The method used is descriptive qualitative with a qualitative descriptive approach and an analysis of conversion of dairy cattle dung into methane gas production. The results showed that the potential for renewable energy from dairy cattle waste to biogas was 4,424 kg / day or equivalent to 35.35 m3 / kg with a methane content of 24.75 m3. The utilization of dairy cattle waste in Jetak Village into compost / organic fertilizer has not been done by the community due to a lack of community knowledge and the motivation of people who are still low in processing livestock waste into other products.

Influence of the blend nickel/porous hydrothermal carbon and cattle manure hydrochar catalyst on the hydrothermal gasification of cattle manure for H2 production

This study presents the optimized hydrothermal gasification (HTG) and hydrothermal carbonization (HTC) of Cattle Manure (CM) and Cattle Feed (Canola Stalks) for hydrogen-rich gas, bio-oil and porous carbonaceous catalyst support production as a potential procedure to handle cattle wastes and produce valuable energy carriers. Our main objective in the present research was to produce H2-rich gas from the wastes of dairy cattle in the presence of the efficient catalyst supported on a support that was prepared from the cattle feed. Therefore, with the aim of improving one of the momentous dimensions in the sustainable development that is the environmental protection, considerable efforts were focused on the maximum exploration of dairy cattle waste materials. Three operating parameters of temperature (380–440 °C), reaction time (5–30 min), and feed concentration (2.5–3.5 wt%) were examined and their optimized levels were found to be 440 °C, 20 min, and 2.5 wt%, respectively. The hydrothermal gasification was performed using Ni catalyst supported on activated carbon canola stalks (ACCs), CM hydrochar that was produced via the HTC and further ZnCl2 chemical activation of canola stalks, and the combination of ACCS and hydrochar (called blend) catalysts under the optimized conditions. The impact of catalyst supports on the distribution of gaseous products was assessed by various techniques and accordingly, the blend catalyst increased the H2 and total gas yields by the factors of 1.73 and 1.66, respectively. Furthermore, the bio-oil of the HTG process was also collected and analyzed using GC/MS analysis and it was found that the CM bio-oil is rich in phenol and its derivatives, furans, Nitrogen-containing compounds, and aromatic molecular structures.

The potential of various livestock waste as sources of methanogenic bacteria

Livestock waste contains organic matter as nutrients for methanogenic bacteria. However, the limiting factor was the acidogens and acetogens continuously produce compounds that reduce the pH of the system below the preferred range for methanogens to survive if sufficient buffering capacity is not available.The objective of this research is to determine the potency of various livestock waste such as dairy cattle waste and beef cattle waste, as a source of methanogens. The technique for counting bacteria was through Total Plate Count in anaerobic Hungate tube. The incubation period was 30 days. Methane was observed using Gas Chromatography (GC) analysis and the concentration of VFAs was measured using titration method. The results showed that methane production was directly proportional to the growth of anaerobic bacteria. Based on the growth of anaerobic bacteria and the production of methane in the media indicated that the dairy cattle waste and beef cattle waste were potential as a source of methanogenic bacteria.

&lt;b&gt;Co-digestion of crude glycerin associated with cattle manure in biogas production in the State of Paraná, Brazil

The addition of different concentrations of crude glycerin, associated with cattle manure, on the volumetric production of biogas is analyzed. Different concentrations of crude glycerin (2, 4 and 6% m m -1 ) were added as supplement in anaerobic co-digestion of dairy cattle waste, in laboratory batch biodigesters (3.5 L usable volume). The biodigesters were operated under mesophilic conditions (30oC), with 30-day hydraulic retention time (HRT). Total solids (TS), volatile solids (VS) and chemical oxygen demand (COD) were analyzed to determine the efficiency of the process in the removal of organic matter and its effect on biogas production. The addition of 4% glycerin provided a larger production of biogas, approximately 9.307 mL. The efficiency in COD removal decreased in treatments with glycerin, with highest reduction (68%) in the control treatment. There was a 90 and 118% increase respectively for Gli4 and Gli6% treatments. VS reductions Gly 0, Gly 2, Gly 4 and Gly 6% treatments were 18.17, 61.60, 24.36 and 44.83%, for the respective treatments.

POTENSI FESES TERNAK SAPI DALAM MENDUKUNG KEGIATAN PERTANIAN (Potential Cattle Feses in Support Agricultural Activity)

Enrekang has approximately 2000 dairy cows were spread across several districts. If the average of the dairy cows produce feces every day as much as 35 kg, so the number of dairy cattle in the district waste Enrekang sebanyhak 70 tons / day. This fact shows the potential for waste is unbelievably big. The waste kepertingan if used for other sectors, such as agriculture, it will also create a promising organic farming. However, if waste is not utilized or dumped into the river or surrounding neighborhood residents, then a few years later would meet dairy cattle waste streams and neighborhoods. The method used for the libah memanfaatakan that use animal feces as a medium for the cultivation of worms, to support activities of livestock cattle feces dimanfaatakan as biogas, then the waste from the biogas is used also as a medium for the cultivation of worms. The results of the activities acquired two flagship products, the first worm which farmed in parentheses obtained within two months of worms doubled the number of sires. Second, the benefits obtained by the former media cultivation of worms into compost. Stool processing technology that diverse is expected to improve the knowledge of farmers in processing the waste so it is not wasted. Processing of pliers berfareasi feces will increase public interest in managing rancher sector so as to create farming systems based Zero Waste. Key Words : Potensi, Peternakan Sapi, Zero Waste

Performance of temperature-phased anaerobic digestion (TPAD) system treating dairy cattle wastes

The performance of temperature-phased anaerobic digestion (TPAD) system in the stabilization of dairy cattle wastes at high solids concentrations has never been evaluated, though the process has been established as a feasible alternative to conventional mesophilic processes for the treatment of municipal wastewater sludges. In this study, the TPAD system operating at a retention time of 14 days was subjected to varying total solids (TS) concentrations (3.46–14.54%) of dairy cattle wastes. At TS concentrations lower than 12.20%, corresponding to system volatile solids (VS) loadings in the range of 1.87–5.82 g VS/L/day, the system achieved an average VS removal of 40.2%. The maximum VS destruction of 42.6% was achieved at a TS concentration of 10.35%. Methane recovery from the wastes was consistently within 0.21–0.22 L/g VS fed. There was a drop in the system performance with respect to VS removal and methane recovery at TS concentrations higher than 10.35%. volatile fatty acid/alkalinity ratios less than 0.35 in the thermophilic reactor and 0.10 in the mesophilic reactor were found favorable for stable operation of the system. For the entire range of TS concentrations, the indicator organism counts in the biosolids were within the limits specified by USEPA in 40 CFR Part 503 regulations for Class A designation. After digestion, nearly 80–85% of total phosphorus was associated with the biosolids.

Waste management systems of dairy cattle farms in Japan

Recently, the size of livestock farms in Japan has been expanding and the pollution from farm wastes has become a serious problem in rural areas. Therefore it is necessary to design treatment strategies and improve the recycling of livestock manure for sustainability of agriculture in Japan. The dairy cattle waste management systems were studied at dairy farms in Aomori prefecture and in Hokkaido, Japan. The four farms, typical for the respective regions in Japan, were investigated on the basis of the land and livestock size, housing, overall farm and waste management, type of machinery and a farm labour force. A statistical comparison was made for housing, milking and waste handling systems of dairy farms. One of the waste handling strategies was aerobic slurry treatment and land irrigation of the treated liquid fraction. Such methods began to solve some of waste management problems created since 1967 in grassland farming areas of Hokkaido. The irrigation system supplies water fertiliser and organic material to land as well as shortening the spreading times. It recycles livestock resources, increases the soil fertility and rationalizes the farm management.

Changes in nitrate N content in different soil layers after the application of livestock waste compost pellets in a sweet corn field

Changes in the nitrate content in different soil layers (0–15 cm, 15–30 cm, 30–45 cm, and below 45 cm) were investigated after the application of livestock waste compost pellets in a sweet corn field located at the National Agricultural Center for Kyushu Okinawa Region. Results indicated that livestock waste composts could lead to a high nitrate content in deeper soil layers of the early stage after the application of compost pellets, and increase the risk of nitrate pollution to underground water through leaching in summer in a rainy area. The dairy cattle (DW), swine (SW), and poultry waste (PW) compost pellets released about 31.5, 41.6, and 51.3% of N in about 3 months, respectively. However, N use efficiency by sweet corn was only 20.5, 20.6, and 28.8%, respectively. In order to enhance the N use efficiency by crops and decrease nitrate leaching to deeper soil layers in the Kyushu area, a large amount of application of animal waste compost pellets at one time should be avoided in summer. The PW compost pellets led to the highest dry matter content in sweet corn in this experiment. Chemical fertilizer treatment led to the highest total water-soluble sugar content in sweet corn seed, but there were no significant differences between the treatments.

N release from livestock waste compost pellets in barley fields

N release patterns from dairy cattle, swine, and poultry waste compost pellets were studied using the buried glass filter paper method in barley fields. Field experiments with barley were also carried out to study the relationship between N release from pellets and N absorption by barley. Results showed that about 28, 36, 44% and of N were released from 3 types of compost pellets throughout the growth stages of barley, respectively. However, since more than 60% of N was released before the tillering stage of barley, barley absorbed a large amount of N and grew excessively in winter. When poultry and swine waste compost pellets were incorporated into dairy cattle waste compost at the N ratio of 1 : 1 or 2 : 1, N release rate from the incorporated pellets decreased, but N was still mainly released at early stage after application. Compost pellets made of dairy cattle and swine waste compost at the N ratio of 1 : 1 led to the highest production of barley in this experiment, followed by compost pellets made of dairy cattle and poultry waste compost at the N ratio of 1 : 1 and poultry waste compost pellets. The use of these three types of pellets resulted in a barely yield higher than that obtained with chemical fertilizers at the significant level of 1%. Amounts of P and K absorbed by barley in the pellet treatments exceeded those in the chemical fertilizer treatments, suggesting that additional application of chemical fertilizer containing phosphorus and potassium was not necessary when animal waste compost was used for barley production as basal fertilizer. Meanwhile, the balance of nutrients, such as N, P, and K, in the compost pellets should be considered also to achieve comprehensive management of nutrients for crop production.

Thermophilic methane production from dairy cattle waste

Methane production from waste of dairy cattle fed diets containing 72% roughage (dry matter basis) was investigated in anaerobic reactors at 60°C with retention times (RT) set at 3, 6 and 9 days. Influent concentrations of volatile solids (VS) were increased in steps of 2% from 4 to 14% VS or until the reactor failed due to excess substrate. Gas production was measured and samples of effluent taken for six consecutive days after allowing three volume turnovers for each increment of VS. The maximum concentration of VS in the substrate for highest volumetric fermentation efficiency was 8–10, 10–12 and 12 for RT of 3, 6 and 9 days, respectively. Destruction of VS for these and lower substrate concentrations was 19–24, 26–27 and 30–33% for 3-, 6- and 9-day RT reactors, respectively. The corresponding methane production rates were 0·09-0·12, 0·11-0·14 and 0·11-0·16 liters/day/g of VS in substrate. The gas contained 51–56% methane with the rest mainly carbon dioxide. Increasing the percentage of feed VS beyond the values indicated resulted in greatly decreased VS destruction and methane production. The dairy cattle waste contained the following constituents as percent of dry matter: Volatile solids (VS) 85, Na 0·37, K 3·8, P 1·0, Si 2, non-ammonia N expressed as crude protein (CP) 18, NH 3N 0·3, cell wall constituents 46, acid detergent fiber 32, hemicellulose 13, cellulose 21, lignin 10, acetate 3·1, lactate 6·6 and ether extract 4. Detailed analyses for organic acids indicated that the efficiency of methanogenesis was, in general, good until increasing organic loading rates caused total organic acid concentration to reach 120–150 m m. As loading rates increased, propionate was the first acid to increase but did not exceed levels higher than 27 m m. Acetate was the second acid to increase and reached levels as high as 150 m m at high reactor loading rates. Butyrate was low or absent initially but was produced at high loading rates, reaching levels of 30–40 m m. Inhibition of methane did not appear to be associated with a change in any specific acid. Isobutyrate and isovalerate plus 2-methylbutyrate, indicative of protein catabolism, accumulated in amounts as high as 5 and 7 m m, respectively, when 10–14% of VS were fed. Little n-valerate, n-caproate, formate or succinate accumulated.

Surface Runoff and Shallow Ground Water Quality as Affected by Center Pivot Applied Dairy Cattle Wastes

ABSTRACT DAIRY cattle wastes were applied to separate areas by center pivot irrigation at mean N rates of 91 and 44 kg/ha per month. Total N was determined on surface runoff samples from each area. Nitrate contamination of shallow ground water was measured in water samples collected from 23 sites, with each site having piezometers at 1.2, 2.4, and 3.6 m. Total cumulative N loads in surface runoff for June 1982-February 1985 from the high and low wastewater rates were 147 and 47 kg/ha, respectively. Mean monthly NO3 N concentrations of 10-70 mg/L, 10-50 mg/L, and 5-35 mg/L were found in the shallow, intermediate, and deep piezometers, respectively. Significant differences in shallow ground water N03~N concentrations were not found between the two wastewater application rates. Substantial NO3 N contamination at 3.6 m occurred despite dense very slowly permeable plinthic and subsoil materials.

Design parameters and operating characteristics of animal waste anaerobic digestion systems. Dairy cattle

The major difference between dairy cattle waste and swine, poultry or beef wastes is the considerably smaller fraction which is biodegradable. Thus, methane yields for dairy waste, when compared with beef, swine and poultry waste at identical operating conditions, are much lower, of the order of 50% of beef waste yields. The VS reduction is similarly about half that of beef and a third that of swine and poultry. This assumes the dairy herd is fed a roughage diet. Two temperatures were studied for dairy waste: 35°C and 60°C. As with beef, considerable literature reports exist for both these temperatures, but all full scale operations now use 35°C. The simulations lead to the following recommended designs for operation in the mesophilic and thermophilic ranges, respectively: temperatures—40°C and 60°C; influent VS concentrations—82·5 and 103 g litre −1 and detention times—8 and 6 days. Since dairy waste is only about half as biodegradable as beef waste, considerable differences exist in start-up and recovery techniques. The minimum detention times as determined by these simulations are 8, 6 and 4 days for 35°C, 40°C and 60°C operation, respectively.