Effect of Adding Flue Gas Desulphurization Gypsum on the Transformation and Fate of Nitrogen during Composting

The objective of this study was to investigate the effect of adding flue gas desulphurization gypsum (FGDG) on the transformation and fate of nitrogen during co-composting of dairy manure and pressmud of a sugar refinery. The ammonia absorption of FGDG was investigated. The changes in compost temperature, pH, electrical conductivity (EC), moisture, organic matter, the C/N ratio, Kjeldahl N, NH₄⁺-N, NO₂^?-N, NO₃^?-N were assessed. The addition of FGDG did not significantly affect compost temperature, pH, EC, moisture, and organic matter degradation. However, the addition of FGDG significantly increased the NH₄⁺-N content in the compost during the thermophilic phase, and the NH₄⁺-N maximal content in the compost with FGDG (CP+G) was 59.9% more than that in the compost without FGDG (CP–G). FGDG was thought to create the formation of (NH₄)₂SO₄ and the cation exchange between NH₄⁺ and Ca²⁺. The NO₂^?-N content in the CP+G peaked on day 15, and was not observed in the CP–G. In the final compost products, the NO₃^?-N concentration in the CP–G was more than that in the CP+G, which was 1451 (CP–G) and 1109 mg·kg^?1 (CP+G) dry material. This might be due to the NO₂^? accumulation in the CP+G, which accelerated N loss in the form of N₂O. There is a strong correlation between N₂O emission and NO₂^?-N accumulation in the composting process. Compared with the original N content in the compost mixture, the N loss in CP–G and CP+G were 15.0 and 10.8%, respectively. These results revealed that NH₄⁺-N conservation effect was improved during the thermophilic phase and the total N loss was mitigated by adding FGDG into composting materials. FGDG could be utilized as a potential amendment to conserve nitrogen during composting.     

Occurrence,Degradation and Fate of Pesticides During Composting

This paper reviews the findings of research reported in the currently available literature regarding the occurrence and transformations of pesticides through the composting process and the use of compost. Part I summarizes the composting process, pesticides and mechanisms of pesticide degradation. Part II reviews research studies concerning the occurrence and fate of pesticides during composting. Investigations of pesticide residues in composting feedstocks and finished compost detected few of the target pesticides. The compounds that were found occurred at low concentrations. The majority of the compounds detected were insecticides in the organochlorine category, including chemicals that have been banned from use in the U.S. for many years. Generally, organophosphate and carbamate insecticides and most herbicides were rarely detected. Comparisons of pesticide concentrations before and after composting also showed organochlorine compounds to be most resistant to biodegradation during composting. With some exceptions, pesticides in other categories decomposed moderately well to very well. Studies that followed the mechanisms of degradation indicate that mineralization accounts for only a small portion of pesticide disappearance. Other prominent fates include partial degradation to secondary compounds, adsorption, humification, and volatilization. In general the research results suggest that the pattern of pesticide degradation during composting is similar to the degradation observed in soils. With a few important distinctions, composting can be considered a biologically active soil environment in which degradation is accelerated. However, as some studies noted, composting does not always speed the degradation of all pesticides. The nature of the pesticide, specific composting conditions and procedures, the microbial communities present, and the duration of composting affect the extent and the mechanisms of degradation.     

Determining the Critical Bulking Agent Requirement For Municipal Biosolids Composting

Air space within municipal biosolids composting feedstock is an important design and operating consideration. Bulking agents, such as woodchips, are required to ensure adequate air space levels are maintained. The purpose of the study was to report on the use of bench-scale air space tests to identify the critical bulking agent requirement (CBAR). CBAR was defined as the minimum amount of bulking agent required to maintain adequate pore space oxygen levels. Bench-scale air space tests were correlated to full-scale windrow composting performance, particularly pore space oxygen levels. Four volumetric ratios of municipal biosolids and woodchips were tested ranging from 1:1 to 1:4 (biosolids:wood-chips). The traditional soil physics methodology was used to determine total air space (TAS). A new step was added to the method which allowed one to also determine the free air space (FAS) within the sample. In addition, the effect of compaction on TAS and FAS was also investigated. Windrows were monitored for pile temperature and pore space oxygen concentration. At the end of the run, maturity, fecal coliform density, and the presence of salmonella were determined. The heavy metal content of the feedstock material, finished compost, and recycled woodchips were also determined. For the materials tested, biosolids and woodchips, the CBARs, to achieve a FAS of ≥20% and a minimum pore space oxygen content of ≥5%, were estimated as 1:2.5 and 1:2.8 (biosolids:woodchips; vol:vol), respectively. Assuming a target pore space oxygen level of > 5%, the recommended air space value depended on the test method used, and ranged from 26 to 61%. Bench-scale air space values were found to correlate to windrow pore space oxygen levels and operating temperature. A significant thermophilic period was not observed in any of the recipes tested. It was speculated this was caused by the coarse particle size of the woodchips. Based on the observations of the metal contents of the materials used in this investigation, the metal content of recycled material should be considered when evaluating the advantages and disadvantages of using recycled woodchips as a bulking agent.     

Literature Review: Occurrence,Degradation and Fate of Pesticides During Composting: Part II: Occurrence and Fate of Pesticides in Compost and Composting Systems

This paper reviews the findings of research reported in the currently available literature regarding the occurrence and transformations of pesticides through the composting process and the use of compost. Part I summarizes the composting process, pesticides and mechanisms of pesticide degradation. Part II reviews research studies concerning the occurrence and fate of pesticides during composting. Investigations of pesticide residues in composting feedstocks and finished compost detected few of the target pesticides. The compounds that were found occurred at low concentrations. The majority of the compounds detected were insecticides in the organochlorine category, including chemicals that have been banned from use in the U.S. for many years. Generally, organophosphate and carbamate insecticides and most herbicides were rarely detected. Comparisons of pesticide concentrations before and after composting also showed organochlorine compounds to be most resistant to biodegradation during composting. With some exceptions, pesticides in other categories decomposed moderately well to very well. Studies that followed the mechanisms of degradation indicate that mineralization accounts for only a small portion of pesticide disappearance. Other prominent fates include partial degradation to secondary compounds, adsorption, humification, and volatilization. In general the research results suggest that the pattern of pesticide degradation during composting is similar to the degradatiion observed in soils. With a few important distinctions, composting can be considered a biologically active soil environment in which degradation is accelerated. However, as some studies noted, composting does not always speed the degradation of all pesticides. The nature of the pesticide, specific composting conditions and procedures, the microbial communities present, and the duration of composting affect the extent and the mechanisms of degradation.     

根系调查取样点数确定方法的研究

根系是植物与外界环境进行物质和能量交换的场所，其分布特征反映了植物对环境的利用程度，随着科学的发展和技术的进步，人们对根系的研究也逐渐从定性走向定量，科学的根系调查方法是进行根系定量研究的关键。在已有的根系调查资料的基础上，应用数量统计的方法，对应用土钻法进行根系调查取样所需要的样点数进行了计算和分析，结果表明，应该按照不同立地，不同取样范围进行根系调查，根据调查的需要和实际状况，确定不同取样范围内所需要的取样点数，并对1／4样圆法的进行了改政和修订，提出了一种新的野外取样的方法。     

Fate of Fusarium graminearum and Other Fusarium Species During Composting Of Beef Cattle Feedlot Manure

Fusarium head blight, caused by Fusarium graminearum, could potentially become a major concern for the cereal industry in Alberta, Canada. Infested feed grain in feedlot manure may act as a means of spreading the disease when manure is land applied. The ability of manure composting to eradicate the pathogen on infested grain (wheat, barley, corn) was evaluated. F. graminearum and other Fusarium spp. were rapidly eradicated from infested grains buried in compost windrows with no recovery after 2 d where windrow temperature attained 51°C. Under cooler windrow conditions (11.9 to 17.5°C), recovery of F. graminearum reached zero on Day 9 for corn (Zea mays L.), Day 14 for wheat (Triticum aestivum L.) and Day 22 for barley (Hordeum vulgare L.), showing that factors in addition to compost temperature may play a role in pathogen elimination. Composting represents an effective strategy in mitigating the dissemination of F. graminearum via manure should land application occur on fields that are subsequently used for grain production.     

Fate of pesticides during beer brewing

The fates of more than 300 pesticide residues were investigated in the course of beer brewing. Ground malt artificially contaminated with pesticides was brewed via steps such as mashing, boiling, and fermentation. Analytical samples were taken from wort, spent grain, and beer produced at certain key points in the brewing process. The samples were extracted and purified with the QuEChERS (Quick Easy Cheap Effective Rugged and Safe) method and were then analyzed by LC-MS/MS using a multiresidue method. In the results, a majority of pesticides showed a reduction in the unhopped wort and were adsorbed onto the spent grain after mashing. In addition, some pesticides diminished during the boiling and fermentation. This suggests that the reduction was caused mainly by adsorption, pyrolysis, and hydrolysis. After the entire process of brewing, the risks of contaminating beer with pesticides were reduced remarkably, and only a few pesticides remained without being removed or resolved.     

Fate of ochratoxin A during vinification of Semillon and Shiraz grapes

Semillon and Shiraz grapes containing ochratoxin A (OA) were obtained by inoculation of bunches on the vine with Aspergillus carbonarius. Citric acid content was greater in the inoculated grapes than in healthy grapes. Samples were collected throughout vinification of these grapes and the OA content was quantified using a stable isotope dilution liquid chromatographic-tandem mass spectrometric method. The mass of processed and waste streams during vinification was also noted. Reduction in the amount of OA in juice and wine occurred at every solid-liquid separation stage. The OA concentration (microg/kg) in white and red wine after racking was 4% and 9%, respectively, of that in crushed grapes. This corresponds to 1% and 6% of the total OA content that was initially present in the inoculated grapes. The OA content was divided between solid and liquid phases at each stage of vinification. OA did not appear to be transformed either chemically or biologically by yeast during fermentation, rather was discarded with the marc, juice lees, and gross lees.     

A Method for Determining Phosphate Diffusion Coefficients by Bulk Diffusion in Soil

A method is described for the determination of phosphate diffusion coefficients by bulk diffusion in soil using the concentration distance method. Two soil blocks only differing in phosphate concentration are brought into contact. After a diffusion period of two weeks the soil blocks are separated, frozen in liquid nitrogen and sliced into layers about 0.02 cm thick by means of a refrigerated microtome. The soil samples are extracted with 4 N HCl, a procedure which fully recovers the added amount of fertilizer P and thus includes the total amount of P that diffuses from one soil block to the other. A concentration distance profile for P and a calculation of the P diffusion coefficient is presented.     

Calculating the Reduction in Material Mass And Volume during Composting

Loss of mass and volume during composting of various feedstocks is an important consideration for compost operation management and facility design. Direct measurements of mass and volume in piles and windrows require specialized equipment and skills that render such measurements impractical for most commercial operations. A study was undertaken to develop a technique for calculating reductions in mass and volume during composting based on the change in concentration of an internal standard and bulk density measurements. Of the various physicochemical parameters investigated, nonvolatile solids (NVS) content proved the most reliable internal standard because of its strong inverse correlation with organic C (r² = ?0.95) and low coefficient of variation (CV = 0.15). Reductions in mass and volume during composting of six windrows comprised of various feedstocks were then calculated using initial and final measurements of NVS and bulk density. Reductions in mass averaged 19.4% of initial mass and ranged from 11.5% to 31.4%. Volume reductions were substantially greater than mass losses, and averaged 40.7% of initial volume. Change in mass was used in combination with organic C contents to calculate the loss of organic C. These losses averaged 28.9% and represented an average 46.4% of total mass loss. Equations for calculating reductions in mass, volume and organic C are presented. These equations may be easily modified to calculate the loss of any measured constituent of compost where the initial and final concentrations are known.     

Method for Determining the Rate and Extent of Accelerated Starch Retrogradation

A method to accelerate and quantitate retrogradation of starch pastes using a freeze-thaw cycle (FTC) process and turbidometric analysis has been developed. Using this method and differential scanning calorimetry (DSC), it was determined that the rate of retrogradation in 2.5% waxy maize pastes was inversely correlated to the rate of freezing, and that the thawing temperature affected perfection of the crystallites in retrograded amylopectin. DSC and X-ray diffraction were used to determine whether the crystallites formed during the FTC process were the same as those formed in starch pastes held isothermally at 4°C. Analysis of retrogradation of pastes of starches from various botanical sources indicated that the method reflects retrogradation in higher concentration pastes. Retrogradation rates were reduced by the addition of sodium dodecyl sulfate. Microstructures of freeze-thaw processed waxy maize and common corn starch pastes were examined.     

A Comparison of Different Bulking Agents for the Composting of Fish Offal

An experiment comparing the effectiveness of three different bulking agents in the composting of fish processing wastes was carried out using small-scale composters operated at ambient temperatures. Fish offal was mixed with each of peat moss, sawdust and wood shavings in a 5:1 ratio by weight. The mixed materials were left undisturbed in the composters for an initial 55 days. They were then mixed and reloaded into their respective composters for a further 95 days of composting. Temperatures were monitored throughout the experiment, while serial physical and chemical analyses of the compost materials were initiated after the mixing. Headspace-gas chromatography was also used to determine the levels of phytotoxic organic acids and phenol. All the compost piles reached thermophilic temperature levels (40–70°C). Due to insufficient pile mass, temperatures over 55°C were not sustained for a sufficient length of time to satisfy the EPA requirements for pathogen reduction. The temperature profiles suggest that ambient temperatures near the freezing point can significantly influence the temperature of compost piles with volumes of 63 liters or less. The results reaffirm the potential of composting as a viable option for utilizing fish processing wastes and the suitability of peat moss, sawdust, and wood shavings as bulking materials. The physical and chemical qualities of the 150-day old composts were comparable to other seafood compost products. Peat moss gave the best results in terms of nitrogen conservation, but is the most expensive option. Monitoring the concentrations of phytotoxic organic acids and phenol using headspace-gas chromatography proved to be a useful method for establishing compost maturity.     

Assessment of Fulvic Acid-Like Fractions during Tannery Waste Composting

Changes in the structural composition of fulvic acids were followed during composting of tannery solid waste after neutralization of its acidity by ammonium or by lime. Different techniques (elemental analysis, Fourier transform infrared (FTIR), ¹³C-NMR spectroscopy) were applied. During both trials of composting, a decrease of carbon and increase of oxygen occurred, which originated from strong microbial oxidation and preservation of some structures during composting. In fact, Nuclear Magnetic Resonance (NMR) spectra showed the preservation of anomeric or tannin structures around 105 ppm. The infrared (IR) spectral data showed a decrease in the intensity of COO^? group bands (1623 and 1399.5 cm^?1); this is correlated with a decrease of fulvic acid levels. The variations observed in NMR spectra could be explained by the involvement of COO^? groups of certain structures in polycondensing to form humic acids. The fulvic acids remain composed of less polycondensed structures with a –COOH extremity, as supported by a decrease of the C/H ratio. In contrast, in the trial with addition of ammonia a slight increase in N content occurred, a decrease in absorbance in the 1730–1000 cm^?1 regions compared to the absorbance around 3400 cm^?1, and a strong decrease of carboxyl carbon in the ¹³C-NMR spectra.     

Composting for the Treatment of Cattle Wastes

? Livestock farming in England and Wales is estimated to produce an annual figure of 200 million tons of animal excreta, half generated by the dairy cattle industry. In the United Kingdom, the structure of the cattle industry has shifted from large numbers of small dairy farms to fewer but larger units. The national average herd size increased from 26 to 42 and finally to 64 animals in 1965, 1975 and 1985, respectively. The latest census revealed that currently there were 2.44 million dairy cows and 9.45 million other cattle and calves in the United Kingdom (total 11.89 million), third place after France (21.50 million) and Germany (19.51 million) in the EEC countries.     

Improving the Aerated Static Pile Composting Method by the Incorporation of Moisture Control

The aerated static pile (ASP) composting method, when operated using a temperature feedback control system is known to produce rapid drying rates through the mechanism of evaporative cooling. Previous work has shown through rewetting ASP, that the moisture content had been lowered to the point of producing an inhibitive effect. In this study, using mixtures of raw sludge and woodchips, the effect of moisture control on the rate of organic matter breakdown, using ASP was investigated. Results suggest that the duration of the thermophilic phase can be extended, to provide a more stringent treatment. However, the rate of sanitization appeared to be retarded, although numbers of indicator organisms detected at the end of the runs indicated that the level of pathogen destruction was adequate.     

Carcass Composting for Management of Farm Mortalities: A Review

For the last two decades, carcass disposal by burial is being replaced with alternatives such as composting. Improper animal mortality disposal may generate various environmental and health hazards such as odor nuisance (resulting from the anaerobic breakdown of proteins) that can reduce the quality of life and decrease property values. Pathogens, which may still be present in the decomposed material, are capable of spreading diseases in soil, plants, animals and humans. The potential leaching of harmful nitrogen and sulfur compounds from animal mortalities to ground water is another concern. To control these side effects, compost facility operators need to know and understand the science and guidelines of carcass composting. While basic principles of carcass composting are similar to those for composting of organic materials, its management issues, including appropriate composting methods for large or small scale carcass composting, quantities and types of carbon sources, composting time, odor and leachate control, and equipment requirements differ from composting of organics. The purpose of this study is to review the previous works related to carcass composting and provide information on recent advances in small and large-scale carcass composting enabling higher decomposition rates, minimum usage of carbon source materials, easier and shorter management control strategies and reduced land requirement while producing a useful end product and avoiding negative impact on public safety and environmental parameters.     

The Fate of Plant Pathogens and Seeds During Anaerobic Digestion and Aerobic Composting of Source Separated Household Wastes

Anaerobic digestion is becoming a more common method for treatment of organic wastes. Little is known, however, about the effects of this process on the fate of plant pathogens and seeds. Therefore, the fates of the plant pathogens Plasmodiophora brassicae, Heterodera schachtii, Meloidogyne incognita, Ralstonia solanacearum, tobacco mosaic virus (TMV) and tomato seeds were followed during anaerobic digestion of source separated household wastes. With the exception of TMV, all test organisms were destroyed to below detectable limits within one day of anaerobic digestion at 52°C. Two days of anaerobic digestion did not reduce the concentration of TMV. However, two days of anaerobic digestion followed by 19 days of high temperature composting at 58°C reduced the concentration of infectious TMV particles by a factor of almost three orders. Anaerobic digestion followed by 12 days of composting at 68°C was even more effective. Although TMV concentrations were not eliminated entirely, we conclude that short-term high temperature anaerobic digestion followed by high temperature composting is a highly efficient process for the eradication of detrimental agents from solid wastes.     

A Model for Temperature Dependency of Thermophilic Composting Process Rate

To suit the purpose of composting, an optimal control of the composting process will be advantageous. Modeling may be useful for predicting how a composting process will proceed, both for the purpose of dimensioning a process plant and for planning the process runs. It may also be applicable for process control. If an applicable mathematic model can be created from a reasonably simple theoretic basis, it may have advantages compared to an empirical model. An equation for the temperature dependency of decomposition rate is proposed for modeling thermophilic composting processes. The equation is derived from a simple chemical model, including enzyme activity applying the Arrhenius equation.     

Emission of Volatile Organic Compounds during Composting of Poultry Litter

The objective of this study was to identify and quantify volatile organic compounds (VOCs) produced during composting of poultry litter. The VOCs produced from in-vessel composting with a controlled aeration system were tested using the F-ITR method by VOC analyzer. Alkanes and alkylated benzenes were emitted in the highest amounts from poultry litter, while aldehydes, terpenes, ketones were emitted in much lesser amounts. Studies showed that VOCs generation was the greatest early during the composting process and greatly reduced thereafter. Composting temperatures were found to affect VOCs. All VOCs were least with the high temperatures generated during composting.     

A Kinetic Model of the Yard Waste Composting Process

A new kinetic concept was applied to the yard waste composting process. Yard waste mixtures with different fractions of grass clippings were composted in pilot-scale vessels. Ammonia emissions were highest with high fractions of grass clippings. Calculation of reaction rate constants was based on heat and materials balances. Although the compost mass ratios (a dimensionless number that describes how far the process has advanced) of the mixtures after composting were similar, their chemical and biological analyses reveal differences. A first order reaction model is presented that can be used for plant design. The effects of temperature and particle size on process kinetics need to be investigated further.