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.     

Organic matter transformations and kinetics during sewage sludge composting in a two-stage system

The use of different proportions of rape straw and grass as amendments in the composting of dewatered sewage sludge from a municipal wastewater treatment plant was tested in a two-stage system (first stage, an aerated bioreactor and second stage, a periodically turned windrow). The composition of feedstock affected the temperature and organic matter degradation in the bioreactor and the formation of humic substances, especially humic acids (HA), during compost maturation in the windrow. The total HA content (the sum of labile and stable HA) increased according to first-order kinetics, whereas labile HA content was constant and did not exceed 12% of total HA. Δlog K of 1.0–1.1 indicated that HA was of R-type, indicating a low degree of humification. Temperature during composting was the main factor affecting polymerization of fulvic acids to HA and confirmed the value of the degree of polymerization, which increased only when thermophilic conditions were obtained.     

Humic substances change during the co-composting process of municipal solid wastes and sewage sludge

The change of the degree of stability of compost during the composting process was a kind of guideline for our study. This stability was estimated by monitoring the chemical fractionation (extraction of humic and fulvic acids, and humin) during two cycles of composting. Change of humin (H), humic-like acid carbon (CHA) and fulvic-like acid carbon (CFA) fractions during the composting process of municipal solid wastes were investigated using two windrows W1 (100% of municipal solid wastes) and W2 (60% of municipal solid wastes and 40% of dried sewage sludge). Humin and fulvic acid fractions in the two windrows decreased since the start of composting process and tend to stabilize. At the end of composting process, humic acid fraction is more important in the windrow without sludge (W1) than the one with sludge (W2). The humification indexes used in this study showed that the humic-like acid carbon fraction production takes place largely during the phase of temperature increase (thermophilic phase), and it appeared very active in the windrow W2. At the end of composting process, the E₄/E₆ ratio value indicated that the compost of W1 is more mature than the compost of W2. The humification ratio (HR) allowed a correct estimation of compost organic matter stabilization level.     

Changes in physical,chemical and microbial parameters during the composting of municipal sewage sludge

Changes in physical, chemical and microbial parameters were investigated during the composting of municipal sewage sludge. Raw sewage sludge (30% dry matter) was mixed with compost from sewage sludge (85% dry matter) in 3:1 ratio (v/v). The mixture was divided into 4 windrows which were composted under the same conditions except the turning factor. The turning was every 7, 10, 15 days and according to the temperature which must be (55–65°C) for windrow 1 (W1), windrow 2 (W2), windrow 3 (W3) and windrow 4 (W4), respectively. Water was added to adjust the moisture content (40–60%). The composting process consisted of 2 periods; fermentation (12 weeks) and maturation (4 weeks). The results showed that the temperature reached the maximum after 12 weeks for W1 and 11 weeks for W2, W3 and W4 and then decreased. The final compost was nearly odourless and black, especially in case of W4. The general trend indicates a decrease in organic matter, organic carbon and nitrogen (N), whereas ash, potassium (K) and phosphorus (P) increased and consequently C/K and C/P ratios decreased. There was a slight increase in C/N ratio. The pH increased and then decreased to near neutrality at the end. The mesophilic bacteria increased during the fermentation period and decreased after that, whereas the thermophilic ones increased with increasing of temperature, decreased after 2 weeks and increased again during the fermentation period and then decreased. The mesophilic and thermophilic fungi were present during the first week and disappeared after that. The final compost was pathogens-free as indicated by the counts of coliforms and Salmonella.     

Evaluation of three composting systems for the management of spent coffee grounds

This study was conducted to evaluate the optimum composting approach for the management of spent coffee grounds from the restaurant and ready-to-serve coffee industry. Three composting systems were assessed, including in-vessel composting, vermicomposting bins, and aerated static pile bin composting, over study periods ranging from 47 to 98 days. Total carbon content was reduced by 5-7% in the spent coffee ground treatments across the three composting systems. Nitrogen and other mineral nutrient contents were conserved or enhanced from the initial to the final composts in all the composting systems assessed. Earthworm growth and survival (15-80%) was reduced in all the treatments but mortality rates were lower in coffee treatments with cardboard additions. A decline in earthworm mortality with cardboard additions was the result of reduced exposure to organic compounds and chemicals released through the decomposition of spent coffee grounds.     

Changes in Bacterial and Fungal Communities across Compost Recipes,Preparation Methods,and Composting Times

Compost production is a critical component of organic waste handling, and compost applications to soil are increasingly important to crop production. However, we know surprisingly little about the microbial communities involved in the composting process and the factors shaping compost microbial dynamics. Here, we used high-throughput sequencing approaches to assess the diversity and composition of both bacterial and fungal communities in compost produced at a commercial-scale. Bacterial and fungal communities responded to both compost recipe and composting method. Specifically, bacterial communities in manure and hay recipes contained greater relative abundances of Firmicutes than hardwood recipes with hay recipes containing relatively more Actinobacteria and Gemmatimonadetes. In contrast, hardwood recipes contained a large relative abundance of Acidobacteria and Chloroflexi. Fungal communities of compost from a mixture of dairy manure and silage-based bedding were distinguished by a greater relative abundance of Pezizomycetes and Microascales. Hay recipes uniquely contained abundant Epicoccum, Thermomyces, Eurotium, Arthrobotrys, and Myriococcum. Hardwood recipes contained relatively abundant Sordariomycetes. Holding recipe constant, there were significantly different bacterial and fungal communities when the composting process was managed by windrow, aerated static pile, or vermicompost. Temporal dynamics of the composting process followed known patterns of degradative succession in herbivore manure. The initial community was dominated by Phycomycetes, followed by Ascomycota and finally Basidiomycota. Zygomycota were associated more with manure-silage and hay than hardwood composts. Most commercial composters focus on the thermophilic phase as an economic means to insure sanitation of compost from pathogens. However, the community succeeding the thermophilic phase begs further investigation to determine how the microbial dynamics observed here can be best managed to generate compost with the desired properties.     

Comparison of static,in-vessel composting of MSW with thermophilic anaerobic digestion and combinations of the two processes

The biological stabilisation of the organic fraction of municipal solid waste (OFMSW) into a form stable enough for land application can be achieved via aerobic or anaerobic treatments. To investigate the rates of degradation (e.g. via electron equivalents removed, or via carbon emitted) of aerobic and anaerobic treatment, OFMSW samples were exposed to computer controlled laboratory-scale aerobic (static in-vessel composting), and anaerobic (thermophilic anaerobic digestion with liquor recycle) treatment individually and in combination. A comparison of the degradation rates, based on electron flow revealed that provided a suitable inoculum was used, anaerobic digestion was the faster of the two waste conversion process. In addition to faster maximum substrate oxidation rates, anaerobic digestion (followed by post-treatment aerobic maturation), when compared to static composting alone, converted a larger fraction of the organics to gaseous end-products (CO₂ and CH₄), leading to improved end-product stability and maturity, as measured by compost self-heating and root elongation tests, respectively. While not comparable to windrow and other mixed, highly aerated compost systems, our results show that in the thermophilic, in-vessel treatment investigated here, the inclusion of a anaerobic phase, rather than using composting alone, improved hydrolysis rates as well as oxidation rates and product stability. The combination of the two methods, as used in the DiCOM^® process, was also tested allowing heat generation to thermophilic operating temperature, biogas recovery and a low odour stable end-product within 19 days of operation.     

Estimation of maturity of compost from food wastes and agro-residues by multiple regression analysis

The composting process of food wastes and tree cuttings was examined on four composting types composed from two kinds of systems and added mixture of microorganisms. The time courses of 32 parameters in each composting type were observed. The efficient composting system was found to be the static aerated reactor system in comparison with the turning pile one. Using the multiple regression analysis of all the data (159 samples) obtained from this study, some parameters were selected to predict the germination index (GI) value, which was adopted as a marker of compost maturity. For example, using the regression model generated from pH, NH(4)(+) concentration, acid phosphatase activity, and esterase activity of water extracts of the compost, GI value was expressed by the multi-linear regression equation (p<0.0001). High correlations between the measured GI value and the predicted one were made in each type of compost. As a result of these observations, the compost maturity might be predicted by only sensing of the water extract at the composting site without any requirements for a large-size equipment and skill, and this prediction system could contribute to the production of a stable compost in wide-spread use for the recycling market.     

Co-composting of oil exhausted olive-cake, poultry manure and industrial residues of agro-food activity for soil amendment

The co-composting of exhausted olive-cake with poultry manure and sesame shells was investigated. These organic solid wastes were watered by the confectionary wastewater which is characterized by its high content of residual sugars raising its COD. Four aerated windrows were performed to establish the effects of confectionary by-products on the compost process. Different mixtures of the agro-industrial wastes were used. During the composting process, physico-chemical parameters (temperature, moisture, pH, electrical conductivity, total carbon and total nitrogen) were studied. The stability of the biological system was noticed after 70 days. The final products were characterized by their relatively high organic matter content, and low C/N ratio of 14-17. The humidification of the windrows with the wastewater seemed to have accelerated the composting process in comparison to a windrow humidified with water. In addition, the organic matter degradation was enhanced to reach 55-70%. The application of the obtained composts to soil appeared to significantly improve the soil fertility. Indeed, field experiments showed an increase in potato yield; the production was 30.5-37.5 tons ha(-1), compared to 30.5 tons ha(-1) with farm manure.     

Methods to improve the composting process of the solid fraction of dairy cattle slurry

Cattle slurry solid fraction (SF) with different dry matter (DM) contents was collected from two dairy farms and composted in static and turned piles, with different sizes and cover types, to investigate the effects of pile conditions on the physical and chemical changes in SF during composting and to identify approaches to improve final compost quality. Thermophilic temperatures were attained soon after separation of SF, but the temperature of piles covered with polyethylene did not increase above 60 degrees C. The rate of organic matter (OM) mineralisation increased for turned piles in comparison to static piles, but the maximum amount of mineralisable OM (630-675gkg(-1)) was similar for all pile treatments. The C/N ratio declined from over 36 to a value of 14 towards the end of composting, indicating an advanced degree of OM stabilisation. Mature compost was obtained from raw SF feedstock as indicated by the low compost temperature, low C/N ratio, and low content of NH(4)(+) combined with increased concentrations of NO(3)(-). The efficiency of the composting process was improved and NH(3)-N losses were minimized by increasing DM content of the SF, reducing the frequency of pile turning and managing compost piles without an impermeable cover.     

Characterization of natural organic matter (NOM) derived from sewage sludge compost. Part 1: chemical and spectroscopic properties

In this study changes in the properties of natural organic matter (NOM) were studied during composting of sewage sludge in a laboratory experiment using the pile method. Typical physicochemical parameters were measured during 53 days of composting including humic fractions. The effects of humification on the molecular properties of humic acids (HA) were investigated by 13C CP/MAS NMR spectroscopy. On the basis of chemical analyses, 53 days of composting sewage sludge with structural material can be divided into three phases: (i) domination of rapid decomposition of non-humic, easily biodegradable organic matter (two to three weeks), (ii) domination of organic matter humification and formation of polycondensed, humic-like substances (the next two weeks), (iii) stabilization of transformed organic material and weak microbial activity. Spectroscopic characterization (13C NMR) of compost humic acids reveals changes in their structures during maturation. The changes are highly correlated with the processes taking place in bulk compost.     

湿度对堆肥理化性质的影响

水分是堆肥微生物生命活动的基础 ,也是堆肥中重要的工艺控制参数。弄清湿度对堆肥微生物及理化性质的影响 ,对于优化堆肥工艺参数、提高堆肥效率、降低投资和运行成本具有重要意义。综述了堆肥湿度研究的动态 ,指出了当前研究中存在的问题 ,并提出了未来的研究方向。大量的研究表明 ,湿度低于 4 5 %或高于 6 5 %都不利于堆肥处理。湿度太高会导致堆料的压实度增加、FAS减少、透气性能降低 ,从而导致堆体内氧气供应不足、堆肥升温困难、有机物降解速率降低、堆肥周期延长。湿度过低 ,水分会限制堆肥微生物的新陈代谢 ,导致微生物活性下降、堆肥腐熟困难。由于鼓风、散热、水蒸发等会使堆体内存在湿度的空间变异 ,也会降低堆肥效率和堆肥产品的质量。另外 ,堆肥湿度还影响堆肥的保肥能力。由各文献得出结论 ,堆肥的最佳湿度范围一般为 5 0 %～ 6 0 %左右     

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.     

Novel static composting method for bioremediation of olive mill waste

This paper presents results obtained on the evaluation of static composting process aimed at bioremediation of the hazardous solid olive mill waste (OMW). The static composting process carried out in gas-permeable polyethylene bags followed the fluctuating temperature and oxygen profiles similar to those seen in aerated composting systems. Static composting resulted in apparent increases and decreases in values for total nitrogen and C:N ratios respectively during the process. The amount of nitrogen (>3%) in the composting end product was in agreement with the Italian legislation (Decreto Legislativo 29 aprile 2010, n. 75) specification for nitrogen fertilizer. A gradual decrease in polyphenols during the storage of compost resulted in a non-phytotoxic composted organic matter high in humic substances. Different respirometric tests also stated high biological stability of the end compost product.     

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.     

Composting of olive leaves and pomace from a three-phase olive mill plant

The composting of olive leaves and olive pomace from a three-phase olive mill was tested as a method for solid waste reuse. The process was carried out using a compost windrow and mixing olive leaves and pomace at a ratio of 1:2. Compost was retained in the windrow for 60 days during which thermophilic temperatures developed for the first 40 days. The compost was then placed into a closed area to mature for another 60 days. The final product proved to be high quality amendment with C/N 27.1 and high nutrient concentrations (N, 1.79%; P, 0.17%; K, 4.97%; Na, 2.8%). Mature compost presented the highest germination index (198%) reported to date, as the germination index in the majority of previous studies is under 80%. Furthermore, tests revealed that addition of 31.5 tons of compost per ha, could increase lettuce yield by 145%.     

The study of the aerobic bacterial microbiota and the biotoxicity in various samples of olive mill wastewaters (alpechin) during their composting process

Five different piles were prepared by mixing olive mill wastewater (alpechin) and alpechin sludge with two bulking agents (cotton waste and maize straw) and two organic wastes with high content of nitrogen (sewage sludge and poultry manure), which were composted by the Rutgers static pile composting system in a pilot plant. The aim of this work was to study the evolution of total nitrogen and different forms of organic matter and evaluate the variation in the aerobic bacterial microbiota present and biotoxicity during the composting process.In piles prepared with alpechin, the use of the maize straw as a bulking agent reduced the nitrogen losses whereas the use of sewage sludge, instead of poultry manure, with cotton waste originated the highest degradation of organic matter. In piles prepared with alpechin sludge a similar evolution of the composting process was observed. There were not great variations during composting in the aerobic bacterial microbiota present in the mixtures. However, the pile prepared with alpechin sludge and maize straw was only one to present bacteria capable of growing in alpechin, and the toxicity study showed that this was only present in the starting mixtures.     

Monitoring the biological activity of the composting process: Oxygen uptake rate (OUR), respirometric index (RI), and respiratory quotient (RQ)

Composting of several organic wastes of different chemical composition (source-separated organic fraction of municipal solid waste, dewatered raw sludge, dewatered anaerobically digested sludge and paper sludge) was carried out under controlled conditions to study the suitability of different biological indexes (oxygen uptake rate, respirometric index, and respiratory quotient) to monitor the biological activity of the composting process. Among the indexes tested, oxygen uptake rate (also referred to as dynamic respirometric index) provided the most reliable values of microbial activity in a compost environment. On the other hand, values of the static respirometric index measured at process temperature, especially in the early stages of the composting process, were significantly lower than those of the dynamic index, which was probably due to oxygen diffusion limitations present in static systems. Both static and dynamic indexes were similar during the maturation phase. Static respirometric index measured at 37 degrees C should not be used with samples obtained during the thermophilic phase, since it resulted in an underestimation of the respiration values. Respiratory quotient presented only slight variations when changing the process temperature or the waste considered, and its use should be restricted to ensure aerobic conditions in the composting matrix.     

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.     

Production of compost from marine waste: evaluation of the product for use in ecological agriculture

The sea contains large amounts of resources that are sometimes considered as waste. Such material includes the waste generated by the fish-processing industry and seaweed that is washed up on shores. In this study, these waste products were windrow composted, along with pine bark as a source of carbon and aeration. The final mix proportions were 20 % seaweed, 20 % fish waste, and 60 % pine bark (v/v). After 10 weeks, stable, well-structured, hygienic compost, which was rich in organic matter and nutrients and had a low metal content, was obtained. Tests for maturity, hygiene, and phytotoxicity, along with a detailed physical and chemical characterization, showed that this compost can be used as an organic amendment and/or growth substrate for use in ecological agriculture. The only limiting feature was the high salinity, which could easily be lowered prior to composting the material.