Patterns and quantities of NH(3), N(2)O and CH(4) emissions during swine manure composting without forced aeration--effect of compost pile scale

To evaluate the NH(3), N(2)O, and CH(4) emissions from composting of livestock waste without forced aeration in turned piles, and to investigate the possible relationship between the scale of the compost pile and gas emission rates, we conducted swine manure composting experiments in parallel on small- and large-scale compost piles. Continuous measurements of gas emissions during composting were carried out using a chamber system, and detailed gas emission patterns were obtained. The total amount of each gas emission was computed from the amount of ventilation and gas concentration. NH(3) emission was observed in the early period of composting when the material was at a high temperature. Sharp peaks in CH(4) emission occurred immediately after swine manure was piled up, although a high emissions level continued after the first turning only in the large-scale pile. N(2)O emissions started around the middle stage of the composting period when NH(3) emissions and the temperature of the compost material began to decline. The emission rates of each gas in the small and large piles were 112.8 and 127.4 g NH(3)-N/kg T-N, 37.2 and 46.5 g N(2)O-N/kg T-N, and 1.0 and 1.9 g CH(4)/kg OM, respectively. It was found that changing the piling scale of the compost material was a major factor in gas emission rates.     

Nitrogen loss in chicken litter compost as affected by carbon to nitrogen ratio and turning frequency

The study was undertaken to investigate the effects of carbon to nitrogen (C:N) ratio and turning frequency (TF) on the loss of total nitrogen (TN) during composting of chicken litter (a mixture of chicken manure, waste feed, feathers and sawdust) with a view to producing good quality compost. Carbon to nitrogen ratios of 20:1, 25:1 and 30:1 and TF of 2, 4 and 6 days were experimented. The initial physico-chemical properties of the litter were determined. During the composting process, moisture level in the piles was periodically replenished to 55% and the temperature, pH and TN of the chicken litter were periodically monitored. Also, the dry matter (DM), total carbon (TC), total phosphorus (P) and total potassium (K) were examined at the end of composting. The results showed that both C:N ratio and TF had significant (p < or = 0.05) effect on pile temperature, pH changes, TN, TC, P and K losses while DM was only affected (p < or = 0.05) by C:N ratio. All treatments reached maturation at about 87 days as indicated by the decline of pile temperatures to near ambient temperature. Losses of TN, which were largely attributed to volatilization of ammonia (NH3), were highest within the first 28 days when the pile temperatures and pH values were above 33 degrees C and 7.7, respectively. Moisture loss increased as C:N ratio and TF increased. In conclusion, the treatment with a combination of 4 days TF and C:N ratio 25:1 (T4R25) had the minimum TN loss (70.73% of the initial TN) and this indicated the most efficient combination.     

NH3, N2O and CH4 emissions during passively aerated composting of straw-rich pig manure

Straw-rich manure from organic pig farming systems was composted in passively aerated static piles to estimate the effect of monthly turning on organic matter degradation and NH(3), N(2)O and CH(4) emissions. Turning enhanced the rate of drying and degradation. The four-month treatment degraded 57+/-3% of the initial organic matter in the turned piles, while only 40+/-5% in the static piles. The turned piles showed low ammonia and N(2)O emissions, 3.9+/-0.2% and 2.5+/-0.1% of total initial nitrogen, respectively. Static piles gave low ammonia (2.4+/-0.1% N(initial)), but high (9.9+/-0.5% N(initial)) N(2)O emissions. Prevalence of anaerobic regions in the static system was supported by the higher CH(4) emissions, 12.6+/-0.6% VS(degraded) for the static vs. 0.4+/-0.0% VS(degraded) for the turned system. It was shown, that straw-rich pig manure with very low C/N ratios could be composted directly without significant NH(3) and N(2)O emissions if turned on a monthly basis.     

Pile mixing increases greenhouse gas emissions during composting of dairy manure

The effect of pile mixing on greenhouse gas (GHG) emissions during dairy manure composting was determined using large flux chambers designed to completely cover replicate pilot-scale compost piles. GHG emissions from compost piles that were mixed four times during the 80 day trial were approximately 20% higher than emissions from unmixed (static) piles. For both treatments, carbon dioxide (CO(2)), methane (CH(4)), and nitrous oxide (N(2)O) accounted for 75-80%, 18-21%, and 2-4% of GHG emissions, respectively. Seventy percent of CO(2) emissions and 95% of CH(4) emissions from all piles occurred within first 23 days. By contrast, 80-95% of N(2)O emissions occurred after this period. Mixed and static piles released 2 and 1.6 kg GHG (CO(2)-Eq.) for each kg of degraded volatile solids (VS), respectively. Our results suggest that to minimize GHG emissions, farmers should store manure in undisturbed piles or delay the first mixing of compost piles for approximately 4 weeks.     

Composting of the solid fraction of olive mill wastewater with olive leaves: organic matter degradation and biological activity

The flocculated solid fraction of olive mill wastewaters, obtained from two different olive oil extraction systems (FOMW1 and FOMW2) was composted, with olive leaves (OL) as bulking agent, by the static pile system (Rutgers). The dynamic of organic matter (OM) degradation during composting and its relationship with the basal respiration and fluorescein diacetate (FDA) hydrolytic activity, as indicators of biological activity, were studied. Two mixtures were prepared: C1, from 65% FOMW1 plus 35% OL; and C2, from 74% FOMW2 plus 25% OL and 1% urea. The biooxidative phase of composting in C1, which had a high initial C/N ratio, was long, leading to a high OM degradation, mainly of the lignocellulosic compounds. The water-soluble organic carbon content, C/N ratio and the urea supplied as a N source for the C2 compost make this mixture more adequate for composting, as it had a shorter composting time than C1, and developed a microbial population with a high metabolic activity. The results for basal respiration in C1 and C2 were correlated at a high probability level with those of FDA hydrolysis, and both parameters can be used for establishing the degree of biological stability of the composting material.     

Dynamics of pruning waste and spent horse litter co-composting as determined by chemical parameters

Co-composting of pruning waste and horse manure was monitored by different parameters. A windrow composting pile, having the dimensions 2.5m (height) x 30m (length) was established. The maturation of pruning waste and horse manure compost was accompanied by a decline in NH(4)(+)-N concentration, water soluble C and an increase in NO(3)(-)-N content. Organic matter (OM) content during composting followed a first-order kinetic equation. This result was in agreement with the microbiological activity measured by the CO(2) respiration during the process. The correlation at a high level of probability found between the OM loss and CO(2) evolution showed that both parameters could be used to indicate the degree of OM degradation that is the maturity and stability phases of the compost studied. Humification parameters data from the organic matter fractionation did not show a clear tendency during the composting time, suggesting that these parameters are not suitable for evaluating the dynamics of the process.     

Enhancing the co-composting of olive mill wastes and sewage sludge by the addition of an industrial waste

In this work, the effect of incorporating an acidic ferrous sulphate waste (SF) over co-composting process of sewage sludge and olive mill solid wastes in a 1:2 v/v wet basis was investigated. The SF used was an industrial by-product of titanium oxide synthesis and its addition resulted in a chemical stabilisation of the wastes at low pH. The optimum dose of SF to enhance the composting of the studied biowastes was a 20% v/v (wet basis) and the best moment for the addition turned out to be whenever the composting piles had achieved the thermophilic range. The addition of SF over the composting process made possible a faster stabilisation, increasing the composting rate from 0.033 to 0.13 d(-1), and leading to a Fe and S rich compost. All composts obtained fulfilled the limits determined by current European and Spanish regulations and presented better characteristics for its use as soil amendment and organic fertilizer than the traditional composts without SF. The optimum dose of compost containing SF was determined through agronomic tests being its value about 18 Ton ha(-1).     

城市污泥强制通风堆肥过程中的生物学和化学变化特征

采用间竭式强制通风堆肥法进行的肥堆体积约4m3,堆肥时间为53d的污泥堆肥试验表明,堆肥的第2天即达高温阶段(≥55℃)并能保持8d,平均最高温度达68℃,局部温度达74℃.粪大肠杆菌由开始时的1.41×105个·g-1降至试验结束时的2.32×101个·g-1.污泥堆肥过程中挥发性固体,总有机C、水溶性有机C、固体有机 C/N比和水溶性有机 C/有机 N比下降明显,而 N、P及重金属含量有所升高.随着堆肥的进程,在前1周堆肥过程中产生的氨氮大幅下降,硝酸盐含量随之升高.相应地,pH在第1周内升高,随后降低.堆肥40d左右,水芹(Lepidiumsativum L.)种子发芽指数即可达 80%.综合堆肥过程中堆温和化学与生物学变化特点,表明污泥堆肥在40d左右基本上接近腐熟,50d后达到完全腐熟.产品外观呈黑褐色,蓬松,无明显异味.     

Composting of de-inking paper sludge with poultry manure at three nitrogen levels using mechanical turning: behavior of physico-chemical parameters.

De-inking paper sludge (DPS) is rich in carbon (C) but poor in nitrogen (N). Thus, it has a high C:N ratio which limits the composting process. Accordingly, the goal of this study was to investigate the effect of three N treatments on DPS composting. Compost piles of 100 m3 were formed by mixing raw DPS with poultry manure and chicken broiler floor litter, giving on average 0.6%, 0.7% and 0.9% total N. The changes in physico-chemical parameters, total weight and fiber losses, and maturity of composting piles of DPS were monitored during 24 weeks. The compost piles had a neutral to alkaline pH throughout the study. Inorganic N decreased whereas organic N increased over time for all treatments. These changes in magnitude were different among N treatments resulting in a final total N content of 0.9% for the 0.6% N treatment whereas final total N contents of 0.7% and 0.9% N were measured for the 0.7% and 0.9% N treatments. The total weight, cellulose and hemicellulose losses were higher in 0.6% N treatment giving the lowest C:N ratio after 24 weeks of composting. However, none of the 24 week-old composts of DPS were mature based on their final C:N ratio and colorimetric test of maturity. Except for copper, their final total trace element contents meet most known standards or guidelines for organic soil conditioners. Overall, 0.6% N treatment was the best to enhance DPS composting using mechanical turning, but a period of more than 24 weeks was required to reach compost maturity.     

Co-composting of soybean residues and leaves in Hong Kong

The goal of this project was to evaluate the feasibility of co-composting of soybean residues and leaves and the effects of turning frequency on compost quality. Soybean residues were mixed with leaves and sawdust in 1:1:3 (w/w wet weight) for achieving a C/N ratio of about 30. Three heaps of about 4 m3 of compost mixtures were prepared receiving a turning frequency of daily (pile A), 3-day (pile B) and weekly (pile C) turning. Different turning frequencies did not significantly affect the changes in pH and volatile solids throughout the composting period. High turning frequency caused a lower electrical conductivity and NH4-N contents as well as a shorter duration of thermophilic phase, because of a high heat loss by evaporation and volatilization of ammonia in the pile. The highest C decomposition of 4% occurred in the pile with a 3-day turning period, which coincided with the higher-nitrogen content in this treatment. All treatments with different turning frequencies reached maturation at 63 days as indicated by the soluble organic carbon, soluble NH4-N, C/N ratio and cress seed germination index. However, increasing the aeration during composting period was beneficial in accelerating the maturation process. Taking into consideration less labour and lower operation costs as compared to daily turning, it can be suggested that a 3-day turning frequency would be more appropriate for reaching acceptable quality of compost and ease in operation.     

Effect of the raw materials and mixing ratio of composted wastes on the dynamic of organic matter stabilization and nitrogen availability in composts of Sub-Saharan Africa

The effect of raw materials and their proportions in initial mixtures on organic matter (OM) stabilization and nitrogen (N) availability during pit composting in Sub-Saharan Africa was assessed using biochemical fractionation and laboratory incubations to characterize composts sampled throughout the composting process. Stabilization of OM occurred more rapidly in mixtures with slaughter-house wastes, it was progressive in mixture with household refuses while tree leaves compost remained unstable. Carbon mineralization from compost samples was positively correlated to water soluble and hemicellulose-like organic fractions. Mixtures containing large proportions of household refuses reached the highest stability and total N but available N remained weak. Slaughter-house wastes in the initial mixtures made possible to reach good OM stabilization and the largest N availability. The nature of initial mixing influenced composting parameters, OM stabilization and N availability. It is suggested mixing household refuses and slaughter-house wastes with tree leaves to reach better amending and fertilizer qualities of composts.     

Bio-degradation of olive mill wastewater sludge by its co-composting with agricultural wastes

The use of maize straw (MS) or cotton waste (CW) as bulking agents in the composting of olive mill wastewater (OMW) sludge was compared by studying the organic matter (OM) mineralisation and humification processes during composting and the characteristics of the end products. Both composts were prepared in a pilot-plant using the Rutgers static-pile system. The use of CW instead of MS to compost OMW sludge extended both the thermophilic and bio-oxidative phases of the process, with higher degradation of polymers (mainly lignin and cellulose), a greater formation of nitrates, higher total nitrogen losses and a lower biological nitrogen fixation. The CW produced a compost with a more stabilised OM and more highly polymerised humic-like substances. In the pile with CW and OMW sludge, OM losses followed a first-order kinetic equation, due to OM degradation being greater at the beginning of the composting and remaining almost constant until the end of the process. However, in the pile with MS and OMW sludge this parameter followed a zero-order kinetic equation, since OM degraded throughout the process. The germination index indicated the reduction of phytotoxicity during composting.     

葡萄籽对猪粪秸秆高温堆肥中微生物群落与碳氮含量的影响

以猪粪与秸秆(鲜质量10.5∶1)为基础,在自制的强制通风静态堆肥反应箱中进行堆肥化试验,研究添加8%葡萄籽对猪粪秸秆高温堆肥中微生物群落演替和碳氮转化的影响.在堆肥化的30 d里,分7次采集不同时期的堆肥样品,测定堆肥中微生物区系、微生物生理群的数量及堆肥碳氮含量.结果表明：添加葡萄籽使堆肥中细菌数量略高、放线菌数量显著增加、真菌数量明显降低,细菌/放线菌下降;氨化细菌和反硝化细菌数量降低;而硝化细菌、固氮菌和纤维素分解菌数量增多;铵态氮和有机碳含量下降,而硝态氮含量明显提高.堆肥中硝态氮含量与放线菌数量呈极显著正相关关系.添加葡萄籽使堆体升温快且高温期稳定,堆肥含水率波动较小,从而使堆肥高温期放线菌和亚硝化细菌的波动较小,数量较高,有利于堆肥中硝态氮含量的增加.     

Microbial degradation and humification of the lawn care pesticide 2,4-dichlorophenoxyacetic acid during the composting of yard trimmings.

The fate of the widely used lawn care herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) during the composting of yard trimmings consisting of primarily leaves and grass is an important unexplored question. In this study, we determined the extent of 2,4-D mineralization, incorporation into humic matter, volatilization, and sorption during the composting of yard trimmings. Yard trimmings (2:1 [wt/wt] leaves-grass) were amended with 14C-ring-labeled 2,4-D (17 mg/kg of dry weight) and composted in a temperature-controlled laboratory scale compost system. During composting, thermophilic microbes were numerically dominant, reaching a maximum of 2 x 10(11)/g. At the end of composting, 46% of the organic matter (OM) present in the yard trimmings was lost and the compost was stable, with an oxygen uptake rate of 0.09 mg of O2 per g of OM per h, and was well humified (humification index, 0.39). Mineralization of the OM temporally paralleled mineralization of 2,4-D. In the final compost, 47% of the added 2,4-D carbon was mineralized, about 23% was complexed with high-molecular-weight humic acids, and about 20% was not extractable (humin fraction). Less than 1% of the added 14C was present in water expressed from the finished compost, suggesting a low potential for leaching of 2,4-D. Very little volatilization of 2,4-D occurred during composting. It is of interest that our results indicate active mineralization of 2,4-D at composting temperatures of 60 degrees C because microbial 2,4-D degradation at thermophilic temperatures has not been previously documented.     

Optimizing composting parameters for nitrogen conservation in composting

A central composite experimental design was used to investigate the influence of environmental composting parameters (moisture, aeration, particle size and time) for legume trimming residues, used on soil restoration, on the properties of products obtained (organic matter, Kjeldahl-N, C/N ratio and nitrogen losses (N-losses)) in order to determine the best composting conditions. A second-order polynomial model consisting of four independent process variables was found to accurately describe (the differences between the experimental values and those estimated by using the equations never exceeded 10% of the former) the composting process. Results of the experiment showed that compost with acceptably chemical properties (OM, 85%; Kjeldahl-N, 3.2%), high degradation and minimum N-losses entails operating at high operation time (78 days), low particle size (1cm), medium moisture content (40%) and medium to low aeration level (0.2-0.4 l air/min kg).     

Co-composting of filter cake and bagasse; by-products from a sugar mill

Thailand has nearly 2 million tonnes of filter cake waste containing 1.8% total N from the sugar cane industry to dispose of annually. Compost studies were conducted to determine how rapidly this material can be converted to a stable product that may be useful in crop production, and to characterize the N transformations. Two kinds of sugar mill by-products were composted, filter cake and filter cake mixed with bagasse, at a 2:1 ratio to reduce the C:N ratio in an attempt to reduce N loss during composting. Materials were mixed manually at 3-5 day intervals during the composting process. Both composts were analyzed at least weekly to measure temperature, pH, NH4+, NO3-, total N content, C loss, and germination index. For both mixtures, the thermophilic stage lasted 15-20 days and was higher than ambient for nearly 80 days. The degradation of organic matter (OM) was rapid in both mixtures to approximately 40 days, after which it began to stabilize. Both mixtures achieved maturity at approximately 90 days as indicated by a stable C/N, low NH4+/NO3-, lack of heat production and a germination index higher than 80%. Mixing filter cake with bagasse helped conserve N during composting. Because N was in excess, approximately 12-15% was lost from the composts. Mixing more bagasse with the filter cake may result in further reduction in N losses. Both composts have potential for use in crop production.     

Monitoring of green waste composting process based on redox potential

Among compostable matrices, green wastes represent a significant fraction which can be used as an amendment after composting. Several indicators, e.g. C(HA)/C(FA) or C/N ratios give information on evolution of the organic matrix during composting. However, measurement of these parameters is complex and requires laboratory conditions. The aim of this study was to propose on site easy-to-measure parameters to monitor composting process, such as redox potential (Eh), related to complex indices such as C(HA)/C(FA), C/N, A(210 nm)/A(280 nm), NH(4)(+)/NO(3)(-) ratios, and total organic matter (OM). Windrows were consisting in a mixture of green wastes such as palm, olive, cypress, pine, mimosa, and bay residues. By using covariance analysis, an opposite correlation between Eh and C(HA)/C(FA) ratio was found. Linear regression of this parameter with Eh was chosen to monitor the composting process. Therefore, Eh can be used to monitor green wastes composting.     

Transformation of organic matter during co-composting of pig manure with sawdust

Co-composting of pig manure with sawdust was studied in order to characterize the organic transformation during the process, using both chemical and spectroscopic methods. Humic acids (HA) and fulvic acids (FA) were fractionated from immature and mature pig manure compost, and characterized. After 63 days of composting, the ratio of total organic carbon and soluble organic carbon decreased to a satisfactory low level and the solid and soluble C/N ratios decreased rapidly for the first 35 days before attaining a constant value, indicating compost maturity. Humification could be responsible for the increase in humic acid proportion during composting. The increase in the aromatic bonds after composting, as indicated by the reduction of C/H and C/O ratios of HA and FA, resulted in a more stabilized product. A substantial increase in high molecular weight compounds along with a small increase in low molecular weight compounds was found in mature compost. Moreover the HA also had more complex organic compounds at this stage. Fluorescence spectral analysis showed an increase in the maximum wavelength of HA associated with the contents of aromatic structures in solution. A decrease in relative absorbance of HA at 1160 cm(-1), 2950 cm(-1) and 2850 cm(-1) was seen in the FTIR spectra indicating the decomposition of complex organic constituents, into simpler ones. Increase in the aromatic compounds with higher stability could account for the relative increase in the absorbance of HA at 1650 cm(-1) and 1250 cm(-1) of the mature compost. The composition of FA was not much altered, indicating most of the degradation of organic matter occurred in HA. Data from organic carbon, C/N ratio, elemental analysis, E(4)/E(6) ratio, gel chromatography, fluorescence and FTIR spectra indicated an increase in polycondensed structures and the presence of more stable organic matter in the mature compost.     

Improving the quality of municipal organic waste compost

The effects of different municipal organic waste (MOW) management practices (shredding, addition of carbon-rich materials and inoculation with earthworms) on organic matter stabilization and compost quality were studied. Four static piles were prepared with: (i) shredded MOW; (ii) shredded MOW+woodshavings; (iii) non-shredded MOW; and (iv) non-shredded MOW+woodshavings. After 50 days, a part of each pile was separated for vermistabilization, while the rest continued as traditional thermophilic composting piles. At different sampling dates, and in the finished products, the following parameters were measured: pH, electrical conductivity, carbon dioxide evolution, and concentrations of organic matter, total nitrogen, water-soluble carbon, nitrate nitrogen, ammonium nitrogen, and extractable phosphorus. Shredded treatments exhibited faster organic matter stabilization than non-shredded treatments, evidenced specially by earlier stabilization of carbon dioxide production and shorter thermophilic phases. Woodshavings addition greatly increased quality of final products in terms of organic matter concentration, and pH and electrical conductivity values, but decreased total nitrogen and available nutrient concentrations. Vermicomposting of previously composted material led to products richer in organic matter, total nitrogen, and available nutrient concentrations than composting only, probably due to the coupled effect of earthworm activity and a shorter thermophilic phase.     

Chemical,Thermal and Spectroscopic Methods to Assess Biodegradation of Winery-Distillery Wastes during Composting

The objective of this work was to study the co-composting process of wastes from the winery and distillery industry with animal manures, using the classical chemical methods traditionally used in composting studies together with advanced instrumental methods (thermal analysis, FT-IR and CPMAS ¹³C NMR techniques), to evaluate the development of the process and the quality of the end-products obtained. For this, three piles were elaborated by the turning composting system, using as raw materials winery-distillery wastes (grape marc and exhausted grape marc) and animal manures (cattle manure and poultry manure). The classical analytical methods showed a suitable development of the process in all the piles, but these techniques were ineffective to study the humification process during the composting of this type of materials. However, their combination with the advanced instrumental techniques clearly provided more information regarding the turnover of the organic matter pools during the composting process of these materials. Thermal analysis allowed to estimate the degradability of the remaining material and to assess qualitatively the rate of OM stabilization and recalcitrant C in the compost samples, based on the energy required to achieve the same mass losses. FT-IR spectra mainly showed variations between piles and time of sampling in the bands associated to complex organic compounds (mainly at 1420 and 1540 cm^-1) and to nitrate and inorganic components (at 875 and 1384 cm^-1, respectively), indicating composted material stability and maturity; while CPMAS ¹³C NMR provided semi-quantitatively partition of C compounds and structures during the process, being especially interesting their variation to evaluate the biotransformation of each C pool, especially in the comparison of recalcitrant C vs labile C pools, such as Alkyl /O-Alkyl ratio.