Slurry Storage Research Articles

Prevalence of bacterial faecal pathogens in separated and unseparated stored pig slurry.

To examine the prevalence and diversity of bacterial faecal pathogens in unseparated slurry, separated solids and liquid fractions from a commercial pig farm. A total of 43 stored slurry specimens originating from a fattening house over the period February-April 2002 were analysed, consisting of unseparated (n = 14) slurry, separated solids (n = 16) and separated liquid (n = 13). Specimens were examined for the presence of five bacterial pathogens including Salmonella spp., Shigella spp., Campylobacter spp., Escherichia coli O157 and Yersinia enterocolitica. Selective enrichment and plating methods were employed for detection of Salmonella spp. and Campylobacter spp. and conventional selective plating techniques for the remaining genera. Antibiogram profiles to 12 antibiotic agents were obtained for all Salmonella isolates obtained. Salmonella spp. were identified in all components of the slurry specimens, whereas Campylobacter spp. was only recovered from the unseparated and separated liquid fractions. In both cases, the separated liquid fraction had the highest prevalence of pathogens and the separated solid fraction had the lowest prevalence. None of the slurry specimens examined were positive for E. coli O157:H7, Shigella spp. or Y. enterocolitica. Twenty-nine isolates of Salmonella were recovered from the slurry specimens, comprising seven serovars, of which Salmonella manhattan was the most prevalent, accounting for over half [15 of 29 (51.7%)] of all Salmonella isolates. Salmonella anatum, Salm. derby, Salm. give, Salm. heidelberg, Salm. simi and Salm. stanley serovars were also recovered. All Salmonella isolates were sensitive to ampicillin, augmentin (amoxicillin/clavulanic acid), chloramphenicol, ciprofloxacin, gentamicin, kanamycin and trimethoprim, but has variable resistance to tetracycline (100%), sulphonamides (84.6%), furazolidone (38.5%), nalidixic acid (15.4%) and streptomycin (15.4%). The majority (57.7%) of isolates displayed antibiotic resistance to at least two antibiotic agents, followed by 34.6% of isolates being resistant to three agents and the remainder (7.7%) being resistant to four antibiotics. This study demonstrated a marked reduction in the prevalence of Campylobacter and Salmonella in the solids component of separated pig slurry. The adoption of control processes such as aeration of slurry prior to its spread onto agricultural land and newer approaches to pathogen reduction should be investigated, to reduce the transmission of pathogens from pig slurry to the environment.

Effect of covering pig slurry stores on the ammonia emission processes.

The aim of this study was to evaluate the effects of different covers (oil, plastic film, perforated polystyrene float, peat and zeolites) on slurry settling characteristics and ammonia emission during storage and following surface application in the field. Laboratory trials were carried out for 15 days using a pilot scale device. Samples of 5 kg slurry were used. At the end of the storage period, distributions of dry matter, pH, total ammoniacal nitrogen and total Kjeldahl nitrogen in slurry were characterized. In the field, ammonia volatilisation was measured for three days using a wind tunnel system. Oil and plastic film retained all ammoniacal nitrogen forms in the slurry, whereas the others reduced ammonia volatilisation by reducing the emitting surface or by adsorbing/absorbing ammonia. Over the whole process studied (storage plus application) ammonia emissions were reduced by 40% by oil up to 65-71% by zeolites with different particle sizes.

Use of cattle farm resources by badgers (Meles meles) and risk of bovine tuberculosis (Mycobacterium bovis) transmission to cattle.

Nocturnal observations, radio telemetry and time-lapse camera surveillance were used to investigate visits by badgers (Meles meles L.) to two cattle farms. During 59 half-nights (ca. 295 h) of observation and 17 nights (ca. 154 h) of camera surveillance, 139 separate visits to farm buildings, by at least 26 individually identifiable badgers from two social groups, were recorded. The badgers, which included three individuals infected with bovine tuberculosis (Mycobacterium bovis), used cowsheds, feedsheds, barns, haystacks, slurry pits, cattle troughs and farmyards to exploit a range of food resources, including cattle feed and silage. Cattle feed was contaminated with badger faeces and badgers also came into close contact with cattle. The minimum number of badgers visiting farm buildings per night was negatively correlated with local 24 h rainfall. We conclude that exploitation by badgers of resources provided by cattle farms constitutes a potentially important mechanism for tuberculosis transmission from badgers to cattle.

Thermal inactivation of chymosin during cheese manufacture.

The aspartic proteinase, chymosin (EC 3.4.23.4) is the principal milk clotting enzyme used in cheese production and is one of the principal proteolytic agents involved in cheese ripening. Varietal differences in chymosin activity, due to factors such as cheese cooking temperature, fundamentally influence cheese characteristics. Furthermore, much chymosin is lost in whey, and further processing of this by-product may require efficient inactivation of this enzyme, with minimal effects on whey proteins. In the first part of this study, the thermal inactivation kinetics of Maxiren 15 (a recombinant chymosin preparation) were studied in skim milk ultrafiltration permeate, whole milk whey and skim milk whey. Inactivation of chymosin in these systems (at pH 6.64) followed first order kinetics with a D45.5 value of 100 +/- 21 min and a z-value of 5.9 +/- 0.3 degrees C. D-Values increased linearly with decreasing pH from 6.64 to 6.2, while z-values decreased as pH decreased from 6.64 to 6.4, but were similar at pH 6.4 and 6.2. Subsequent determination of chymosin activity during manufacture of Cheddar and Swiss-type cheese showed good correlations between predicted and experimental values for thermal inactivation of chymosin in whey. However, both types of cheese curd exhibited relatively constant residual chymosin activity throughout manufacture, despite the higher cooking temperature applied in the manufacture of Swiss cheese. Electrophoretic analysis of slurries made from Cheddar and Swiss cheese indicated decreased proteolysis due to chymosin activity during storage of the Swiss cheese slurry, but hydrolysis of sodium caseinate by coagulant extracted from both cheese types indicated similar levels of residual chymosin activity. This may suggest that some form of conformational change other than irreversible thermal denaturation of chymisin takes place in cheese curd during cooking, or that some other physico-chemical difference between Swiss and Cheddar cheese controls the activity of chymosin during ripening.

Gülleerdbecken - Größe und Erfahrungen

In order to gather knowledge about dissemination, dimensions and utilisation of lagoons for storing slurry, a survey of 150 farmers was carried out in August 2000. The average lagoon size was a remarkable 1877 m3. Despite the relatively high space requirements, the low cost construction, as well as the simple handling, motivated a high degree of satisfaction among the farmers. Since it seems that there are lower ammonia emissions from the lagoon (see the Krause&Hartung paper in this edition), this form of slurry storage will become more widespread, despite permit requirements.

Redox-driven changes in porewater chemistry in the unsaturated zone of the chalk aquifer beneath unlined cattle slurry lagoons

Farm waste stores such as cattle slurry lagoons are widespread in the UK and many overly important aquifers. Stores can be serious risks to water quality because they are important sources of N species, organic C and pathogenic microbes. At two sites on the Chalk aquifer of southern England, inclined boreholes were drilled and cored to obtain aquifer material from directly beneath unlined slurry stores. Vertical boreholes were also drilled adjacent to the slurry stores to determine any lateral movement of contaminants. Interstitial porewaters were analysed for major and minor ions and S isotopes. At the second site, unsaturated zone gases were sampled from the inclined hole. Infiltration of slurry into the unsaturated zone caused significantly elevated concentrations of metals such as Cu and Ni at both sites. Sulphate reduction was occurring at Site 1, as evidenced by SO 4 concentrations decreasing from 150 to 50 mg/l and enhanced ratios of δ 34S–SO 4 and δ 18O–SO 4. Ammonium-N also leaches along with dissolved organic C which were found 17 m below ground surface at concentrations up to 400 and 260 mg/l, respectively. Contaminant concentrations were similar in the porewaters from both the inclined and vertical boreholes. At Site 2, higher contaminant concentrations were found in the inclined borehole compared with the vertical borehole. Organic C concentrations were considerably lower than at Site 1, ranging from 10 to 70 mg/l. Ammonium–N concentrations reached a maximum concentration of 25 mg/l, however NO 3-N concentrations were up to 500 mg/l and SO 4 concentrations were generally higher than Site 1. Data for N 2/Ar and δ 15N–N 2 from the gas samplers show a peak of 102 and 2.2‰, respectively, at 14 m below ground level indicating denitrification was taking place. Evidence from δ 34S–SO 4 and δ 18O–SO 4 suggest that some SO 4 reduction was taking place simultaneously. From CH 4 and NH 3 detected at depth it is suggested that slurry contamination, emanating from early use of the store, has passed through the top 18 m of the unsaturated zone at Site 2. The presence of high concentrations of NO 3 and lower concentrations of organic C suggests that this lagoon has formed a relatively impermeable seal at its base within the first few years of its lifetime. The anoxic conditions at both sites may have mobilised U from N–P–K fertilisers. Both sites are continuing to impact on the porewater chemistry and pose a risk of groundwater contamination.

Effects of catalyst activity profiles on polyethylene reactor dynamics

AbstractThe dynamics and stability characteristics of slurry loop and tank reactors were studied using continuation analysis to examine the effects of catalyst activity profiles on reactor dynamics. The production of high‐density polyethylene through the copolymerization of ethylene with hexene was studied using catalysts of the decay type (for example, TiCl4 on silica, or other Ziegler‐Natta catalysts) and the buildup‐type (for example, chromium oxide catalysts on silica of the Phillips type). Sustained oscillations were found to exist for decay‐type catalysts in loop reactors. For both tank and loop reactors, the buildup‐type catalyst exhibited isolated solution branches (isola) and multiplicity phenomena in addition to sustained oscillations. The sigmoidal shape of the buildup‐type catalyst rate curve is postulated as the reason for the additional multiplicity and isola phenomena. The implications for industrial operating conditions are discussed.

A survey of the production and use of animal manures in England and Wales. III. Cattle manures

Abstract. A survey of cattle manure management was undertaken in England and Wales, in 1997, by postal questionnaire sent out to a stratified sample (by unit size) of 1750 dairy and 1750 beef producers. The level of response obtained, with 471 dairy farmers (27%) and 515 beef farmers (29%) returning questionnaires, reflects well on the interest shown by the industry and on the survey design. The survey provided information on manure production and storage, when and how applied and nutrient value. Dairy farms are estimated to produce manures in the form of c. 65% slurry and 35% farmyard manures (FYM) and, beef units, 80%FYM and 20%slurry (based on survey response data, animal numbers and calculations of undiluted outputs of excreta). Slurry storage within both dairy and beef systems is typically up to 3–6 months capacity, although there is no storage for an estimated 16% of dairy and 25% of beef slurry. Autumn and winter spreading is common practice, with 40–50% of slurry and 50–60% of FYM applied at that time. Although some evidence suggests that farmers make little allowance for the nutrient content of manures in planning fertilizer inputs, the results of this survey suggest that many farmers do make some effort to utilize manure nutrients. However, they currently fail to be assured by the advice available to them or they lack confidence in manures as nutrient sources for a number of technical reasons. Information provided by the survey may be important to policy makers, researchers and consultants, as well as farmers.

Field and modelling studies to assess the risk to UK groundwater from earth‐based stores for livestock manure

Abstract. Boreholes have been constructed at eight sites on the Permo‐Triassic Sandstone and Chalk aquifers to assess the extent of chemical and microbiological contamination emanating from unlined farm manure stores. Slurry along fracture faces in the Chalk was found on cores taken from beneath two stores. Porewaters from the Chalk sites and one of the Sandstone sites were discoloured and showed high concentrations of nitrate, ammonium and organic carbon to depths in excess of 10 m. Although Cryptosporidia and Escherichia coli O157 were found in many of the cattle slurry lagoons, neither were found in the aquifer material beneath. The self‐sealing of unlined slurry stores is seen as a crucial step in minimizing leakage. A simple mass balance shows farm boreholes near to contaminant sources are at greater risk than public supply wells. Contaminant modelling shows discontinuing use of an unlined farm manure store will lead to little difference in solute concentrations over the short to medium term. Groundwater is most at risk where the water table is shallow since direct hydraulic connection between the lagoon base and the water table considerably increases the rate of vertical migration. This is of greatest significance for pathogens that are thought to be relatively short lived in the subsurface. Under the majority of situations minimal threat is posed to potable groundwater drinking supplies.

Güllebehältern aus Stahlbeton

Slurry storage is necessary for protecting the environment. Of the competitive construction materials, reinforced concrete is used the most. Farmers have been complaining for years that procedures for attaining building permits take too long, are difficult, involve too much red tape and constructional requirements. In a new experimental series, the corrosion process within the concrete with slurry, and water as a reference liquid, was investigated.

MEASUREMENT OF LEAKAGE FROM EARTHEN MANURE STRUCTURES IN IOWA

Leakage from a representative sample of 28 earthen manure storage structures and lagoons (selected from 459 built in Iowa between 1 January 1987 and 31 December 1994) was determined using a water-balance approach. Forty-three percent (43%) of tested structures had leakage rates significantly (p < 0.05) lower than the regulatory limit of 1.6 mm/d (1/16 in/d) specified by the State of Iowa at the time the basins were constructed. Leakage from 53% of the structures was too close to the regulatory limit to be categorized as being significantly above or below it. One structure (4%) exhibited leakage significantly greater than the regulatory limit. Regression analysis indicates a slight, but statistically significant, decline in leakage rate with increasing structure age. Structures constructed in glacial till showed significantly lower leakage rates than those constructed in sand and gravel, colluvium, or loess. Comparison of slurry pits and lagoons showed no significant difference in leakage rate.

Quantitative Effects of Feed Protein Reduction and Methionine on Nitrogen Use by Cows and Nitrogen Emission from Slurry

The effects on N use and N volatilization from slurry were investigated in 24 early-lactation Brown Swiss cows (32 kg/d milk) fed four diets with 128, 124, 147 and 175 g/kg DM of crude protein (CP). All diets were supplemented with 0.75 g/kg of rumen-protected Met except for one of the low-protein rations (128 g/kg of CP). The unsupplemented low-protein ration was calculated to be deficient in Met by approximately 20%. No significant treatment effects on performance, water intake and excretion, and slurry quantities were observed. Differences in N intake were closely reflected in the daily excretions of total and urea N via urine, and in urine N as a proportion of total excretory N. These values were higher for the unsupplemented low-protein ration than for the Met-supplemented low-protein ration. The treatment effects on fecal N excretion were generally smaller, and milk N excretion and N balance were not affected. Feed N utilization for milk N excretion increased with decreasing CP content from 27% for the high-protein group to about 35% for the two low-protein groups. Comparing the Met supplemented rations only, ammonia N emission from fresh slurry (excreta:water = 1:0.5) decreased from 231 to 160 and 55μg/s per square meter of surface with 175, 147 and 124 g/kg of CP, respectively, and the corresponding total N losses during 7 wk of slurry storage declined from 89 to 57 and 25 g/d per cow. Regression analysis demonstrated the basic suitability of milk urea N excretion to estimate urine N excretion and, consequently, potential N emissions.

Spatial and temporal hydrochemical changes in groundwater under the contaminating effects of fertilizers and wastewater

Contamination of well water in a rural area and of spring water in an urban area by effect of animal slurry management and storage practices, and the municipal water supply network were studied. For this purpose, a number of factors including electrical conductivity, dry residue, pH, dissolved oxygen, nitrate, nitrite, ammonium, organic matter, turbidity, colour, iron, manganese, copper and zinc were examined. Data were subjected to multivariate principal component analysis and cluster analysis. The statistical interpretation of the results allowed two principal factors (F1and F2) to be assigned to saline and organometallic contamination, respectively, of the water. The axes of the plots of factor loadings represent the overall water concentration-dilution effect (F1) and oxidoreduction (F2), respectively. The spatial distribution of the samples is dictated by the prevailing type of contamination. In temporal terms, however, samples cluster by date in urban springs and by contamination type in rural wells.

The effects of storage in maize silage and cattle slurry on the germination of Abutilon theophrasti Med. seeds

The effects of storage in maize silage and cattle slurry on the germination of Abutilon theophrasti Med. seeds

Development of an Automated and Modular System for Slurry Tanks

Uncontrolled agronomic utilisation of waste slurries create non point pollution. GPS supplies position data for precise distribution with automated modular systems. Data inputs (from field activity monitoring) and elaborations are recorded on memory cards and transferred between "farm PC" and "tractor PC". Electronic bus connects tractor with implement devices. This technology controls slurry tanks performances and correct application rate. Centimetre DGPS accuracy and high actuators response speed are required. Different receivers accuracy was tested. Real time measurements transmitted between master and rover receivers are now best supplied by radio modems. The purpose is to receive corrections by GSM or Internet network.

Greenhouse Gas Emission from Stored Livestock Slurry

AbstractAnimal manure contributes about 40% of the total methane (CH4) and 20% of the total nitrous oxide (N2O) emissions in Denmark. We measured the CH4 and N2O emissions from stored cattle slurry and fermented slurry during fall 1996 and summer 1997 and evaluated the effect of surface covers consisting of straw, floating leca pebbles, or a natural surface crust on the patterns of these emissions. No emission of N2O was measured during periods with more rain than evaporation from the slurry stores and no emission was measured from uncovered slurry, irrespective of climatic conditions. During the summer storage with drying conditions, N2O emissions of up to 25 mg N m−2 h−1 were recorded from slurry with surface covers. Total N2O emission was highest from digested slurry. The emission of CH4 from stored fermented slurry and cattle slurry varied between &lt;0.01 and 1.4 or 0.7 g CH4—C m−3 h−1, respectively. The log‐transformed emissions were linearly related to the inverse temperature. Emission of CH4 was reduced, on average, by 38% with surface covers. The reduction was probably due to CH4 oxidation in the surface covers or in the interface between the cover and liquid in the store. Fermentation did not reduce CH4 emissions during storage of the slurry.

Tangential flow separation and chemical enhancement to recover swine manure solids, nutrients and metals

A mobile unit of a tangential flow separator (TFS) system was installed at a swine farm. System performance was evaluated through tests conducted on 11 different occasions between February and August of 1997 with flushed wastes and lagoon liquid. The TFS unit consists of a lime slurry tank, a pre-floc mixing tank, a TFS tank, a thickening tank and associated pumps and flow meters with a processing capacity of 110 m 3/d. Previously screened wastes were mixed with lime in the pre-floc tank, ferric chloride and polymer injected into the flow after pre-floc tank, and flow introduced to the TFS tank tangentially to the wall, creating a circular motion within the tank. The fluid dynamics tends to concentrate solids to the center of the tank where they settle to the bottom. Approximately 75% of incoming flow are discharged at the top as treated effluent, with reduced organic and nutrient content, and flow to a storage lagoon. The settled solids that accumulate at the bottom of the TFS tank flow into a thickening tank of similar design to the main unit in order to further concentrate the solid material (up to 5% total solids). System performance expressed as percentage reduction is better when flushed wastes are processed compared to lagoon liquid. Total phosphorus (Total-P) removal can be higher than 90% depending on the amount of chemicals used. The system can remove an average of 22% total Kjeldahl nitrogen (TKN), 49% chemical oxygen demand (COD), 50% volatile solids (VS), 82% total suspended solids (TSS) and 87% copper (Cu) and zinc (Zn). Percentage reductions obtained with lagoon liquid are generally lower than with flushed wastes. However, the concentrations in effluent from the TFS system are lower for lagoon liquid than for flushed wastes. Typical concentrations of chemicals are about 2000 mg/l of hydrated lime, 400 mg/l of ferric chloride, and 20 mg/l of polymer. Chemical costs can be significant and must be balanced with improvements in effluent quality and potential economic value of sludge.

A survey of annual pesticide usage during the control of sheep ectoparasites in Northern Ireland, 1997

This is the third survey of control practices for ectoparasites on sheep farms in Northern Ireland, providing data comparative to those recorded in previous surveys in 1981 and 1988. Data relating to all aspects of ectoparasite control were collected from 210 farms representing 4% of the total sheep population. Quantitative data have been adjusted to provide accurate estimates of total pesticide usage. Since the previous survey in 1988, the number of sheep farms in Northern Ireland has increased by 10% to 11 692 with a consequent 39% increase in sheep population to 2.9 million. Despite this level of expansion, the total quantity of organophosphorus compounds used for ectoparasite control has remained approximately constant at 7–8 tonnes. The report considers that compulsory sheep-dipping, prescribed since 1970 and revoked in 1993, impacted significantly on subsequent ectoparasite control practices and consequent pesticide usage. During 1997, approximately 20% of sheep farmers relied on alternative methods to control ectoparasites, including injectable formulations of avermectins and pour-on formulations of insect growth regulators and pyrethroids. Dipping formulations containing pyrethroid compounds, which accounted for <1% of treatments in 1988, increased to 9% in 1997. Previously, regulatory sheep-dipping periods were specified during the autumn months, which tended to increase dipping frequency. The majority of farmers dipping sheep during the summer strictly for blowfly maggot (Diptera: Calliphoridae) control were required to perform additional compulsory sheep-dipping during the autumn. Withdrawal of compulsory sheep-dipping has allowed farmers to synchronise dipping practices to control the major ectoparasites of sheep at a single dipping occasion. An estimated 7.5 × 106 litres of surplus dipwash required disposal and there were approximately equal numbers of farmers disposing dipwash immediately after sheep-dipping or on occasions up to and including subsequent dipping. The decline in the number of farmers who allowed dipwash to run-off into soakaways or surrounding soil observed in 1988 continued in 1997. The majority of farmers used tractor-operated pumps to dispose of dipwash into slurry tanks for subsequent disposal onto permanent pasture. © Crown copyright 2000. Reproduced with the permission of Her Majesty's Stationery Office. Published for SCI by John Wiley & Sons, Ltd.

Reducing nutrient losses on dairy farms in The Netherlands

In the European Union, nutrient management is a topic of major political interest. The goal for nitrogen (N) is that groundwater should contain less than 50 mg nitrate/l. The general approach might result in a maximum amount of N or in a maximum number of cattle allowed per ha. However, individual countries develop alternative routes and take additional measures to deal with nutrient losses. In The Netherlands, ammonia volatilization (emission) should be reduced by 50–70% in the year 2000 compared with 1980, in addition to the European guideline for nitrate. Emphasis is placed both on phosphorus (P) and on nitrogen. Regulations limit the amount of manure (expressed in P) applied per ha. A manure (P) quotum has been allocated to each farm. A more balanced P-supply to the land has been achieved by transport of manure from surplus to deficit areas. Also lower P-contents of the concentrate feeds are stimulated. N-losses can mainly be reduced by adapting the farm operation. In this context several management practices were studied with a dairy-farm-simulation-model. A combination of a more efficient use of fertilizer N and restricted grazing in combination with a more balanced ration, resulted in considerable reductions in nitrate leaching. Application of slurry by injection techniques diminishes the ammonia volatilization at farm-level by almost 50%. Other low emission techniques, such as low emission housing and covering of slurry storages, have relatively high costs. In practice, slurry application by injection and covering of slurry storages have become obligatory. As a side effect, the odour of manure is largely eliminated from the environment as well. Application of manure to the land is only allowed in the growing season. From 1998 on, dairy farmers have to keep records of the nutrients on a nutrient balance sheet. On the basis of the nutrient balance a tax will be imposed on surplusses of N and P.

Using Linear Programming to Minimize Manure Storage and Application Costs in Pork Production

Various computer models have been developed to assist producers in planning manure and nutrient management programs. None of these models incorporates fixed costs associated with manure storage, hauling, and application. Current methods for calculating manure application rates require information such as nutrient content in manure, availability of nutrients for use as a fertilizer, and loss factors for different storage and application methods. The objective of this study was to develop a linear programming model that incorporates economic data on fixed and variable costs that can be linked to existing manure management computer models. An example with respect to swine (Sus scrofa) production is presented for various enterprise systems. As the size of the swine enterprise becomes greater than 150 sows, earthen lagoon storage and irrigation application becomes the optimal least cost method. Least cost storage and application costs for the 1200 sow operation was 63% of the least cost solution for the 150 sow operation. Within the same storage and application system, the 1200 sow operation had 77% of the per pig costs for a 300 sow operation. For enterprises with fewer sows, deep pit storage and injection application is the least cost choice.