Evaluation of Changes in CEC During Composting

Changes in cation exchange capacity (CEC) during composting were evaluated with respect to compost amending, and compost processing. CEC_dm (CEC on dry matter basis), CEC_om (CEC on organic matter basis), and CEC_C (CEC on carbon basis) are parameters used for describing properties of composts. In this study effective cation exchange capacity (ECEC) was determined during drum composting; sampling from the infeed (FM) and the outfeed (DC0), and during curing in experimental heaps; sampling when the compost was turned first time (DC1), second time (DC2), and third time (DC3). The ECEC_dm was 18.1 (cmol+/kg) in FM, 35.5 in DC0 and 70.5 in DC3; this rise in ECEC_dm being beneficial from compost amendment standpoint. The ECEC_om was 20.6 (cmol+/kg) in FM, 41.5 in DCO and 89.8 in DC3, whereas ECEC_C was 39.3 (cmol+/kg) in FM, 77.2 in DCO and 183.1 in DC3. When ECEC was expressed on carbon mole basis (ECEC_molC), it was c. 0.5 (cmol+/Cmol) in FM, c. 0.9 in DC0 and c. 2.2 in DC3. These changes in ECEC_om, ECEC_C and ECEC_molC are valuable from the compost quality standpoint. Because the basis of CECdm, as well as, of CEC_om and CEC_C, is affected by composting, they can not be used in determining the effects of composting on the actual number of CEC sites. The amount of ash is not affected by composting, and thus ash basis can be used for determining the effects of composting on the actual number of cation sites. It was shown in this study, that during composting of manure the actual number of effective cation exchange sites increased from DC1 to DC3 by 34 percent, whereas at the same time ECEC_dm, ECEC_om and ECEC_C increased by 99 percent, 116 percent, and 137 percent, respectively. Based on CEC data reported in this paper and in compost literature, it was concluded, that changes in the number of CEC sites due to composting is overemphasized, when unanchored CEC_dm, CEC_om or CEC_C is used.     

Evolution of Biochemical Parameters During Composting of Urban Wastes

An experiment was performed for evaluating the most suitable biochemical parameters to measure dynamics of substrate transformation during composting of the organic fraction derived from preselected urban wastes and wood bark mixture. Changes of chemical (organic C, hydrosoluble sugars, total and mineral N, humified fraction, volatile acids and phenolic compounds) and biochemical (microbial respiration, biomass C, qCO₂, dehydrogenase, catalase, urease activities, FDA, and BIF) parameters were monitored for 120 days. Limited changes in organic C, total nitrogen, and humification characteristics were observed during composting. Dehydrogenase and catalase activities, BIF and FDA showed small changes during composting. Urease activity and, with some limitations regarding the early stages of composting, microbial respiration and qCO₂, were found to be the most suitable parameters to measure dynamics of substrate transformation during composting of preselected urban wastes.     

Changes In Moisture Retention Properties Of Five Waste Materials During Short-Term Mesophilic Composting

The effect of composting for a maximum period of 90 days on the water retention characteristics of five waste materials — coconut dust (CD) (also known as coir), mixed sawdust (SD), rice hulls (RH), sapwood sawdust (SW) and heartwood sawdust (HW) was investigated with or without the addition of nitrogen. Total porosity (TP), easily available water (EAW) and water buffering capacity (WBC) were increased with time in all five materials, while air space (AS) was decreased in all the materials except in rice hulls, where it increased. Of all the materials, CD retained the most moisture and RH the least after 90 days. SD, SW and HW had similar characteristics, and separation for utilization is unnecessary. Nitrogen addition did not affect TP and AS but slightly increased EAW and WBC. Formulation and management of potting media using these materials should take into account these moisture retention changes for maximum benefit to plants grown in them.     

Windrow Composting Of Biodegradable Packaging Materials

The disintegration of Biopol-coated cardboard, polylactide fabric and film was studied using three different procedures: adding the samples directly to the compost pile, and placing them in the pile in nylon bags as well as in steel frames. Cellulose-based sausage casing, polyethylene and Mater-Bi ZF03U were also tested in steel frames as reference samples. Direct addition of the samples to the compost pile had no detrimental effect on the decomposition of compost biowaste. The use of steel frames proved to be good a method for testing samples like packaging materials. Both polylactide samples and Biopol-coated cardboard degraded completely in the steel frames. The results showed that composting activity parameters should be followed during composting before any conclusions can be made about the compostability of the samples. The compost produced from the polymer samples showed no toxicity in the plant growth test with barley and radish seeds performed at the end of the experiment.     

Influence of Raw Materials and Processing Conditions on Spaghetti Hydration Kinetic During Cooking and Overcooking

A study of the influence of raw materials and processing conditions on the hydration kinetic during cooking and overcooking of spaghetti is presented. Water sorption tests on commercially available spaghetti and on three different types of homemade spaghetti were run at 100°C. In particular, the weight, diameter, and length of spaghetti strands were monitored over time for ≈200 min. The spaghetti hydration process was quantitatively resolved into the controlling phenomena (i.e., water diffusion, macromolecular matrix relaxation kinetic, and residual deformation release kinetic) by fitting a novel mathematical model to the experimental data. The different behavior of spaghetti was analyzed for each of the phenomena involved during hydration. Results suggest that processing conditions highly influence the quality of spaghetti with respect to raw materials.     

Biological Evaluation of Seaweed Composting

Large quantities of green seaweed, linked probably to eutrophication, are cast ashore every summer on the Puerto Madryn beaches (Patagonia, Argentina, 42°S, 65°W). This algal biomass interferes with recreational uses of the beach, and therefore must be periodically collected and disposed. Part of this algal biomass was composted with the objective to produce an amendment to improve physical and nutritional characteristics of some local soils used in intensive horticulture, and at the same time to find a way to reduce environmental pollution. The compost was then biologically evaluated by determining the growth rate of tomato plants cultivated on various substrata (washed sand, sandy loam soil, and sandy loam soil plus inorganic fertilizers) to which different doses of compost were added. Results showed that in all cases the addition of compost increased water holding capacity and plant growth. The increase of tomato plants (Licopersicum esculentum var. platense) was proportional to the compost doses. Also, plants grown on sustrata containing at least ten percent compost had significant benefits compared to control plants, improving growth and water stress resistance. Although the quality of this seaweed compost was limited by excessive amounts of sand and low nitrogen content, it proved to be a good amendment that improved both physical and nutritional characteristics of local sandy loam soils used in intensive horticulture. According to these results, composting is a useful technology both to solve environmental pollution problems and to produce a valuable organic fertilizer for soils.     

Operational Parameters for Composting Night Soil in Korea

Recently composting of organic wastes started to gain popularity in Korea. The purpose of this study was to investigate the effect of operational parameters on night soil composting. Operational parameters investigated included compost recycle ratio and temperature control. Lab-scale composting reactors were used in this study. At the recycle ratio of 10 percent, reduction of both volatile solids and moisture content was greater than that at the recycle ratio of 0 percent and 30 percent. This result means that composting reaction was the most active at 10 percent recycle ratio. Temperature control played a important role in the night soil composting process. The greatest decrease in volatile solids was observed when the temperature of composting process was set below 60°C. Also, the amount of CO₂ evolved was the greatest when the maximum temperature was set below 60°C. Kinetic study indicated that first order kinetics described volatile solids reduction very well.     

Microbial Population Dynamics and Enzyme Activities During Composting

The changes in population size of different microbial groups (total aerobic heterotrophs, actinomycetes, fungi, fecal coliforms, ammonium- and nitrite-oxidizing bacteria, and denitrifying bacteria) and the activities of 19 different enzymes (three phosphatases, three esterases, two proteases, three amino-peptidases, and eight glycosyl-hydrolases) were examined during cocomposting of poultry litter (a mixture of poultry manure, waste feed, feathers, and wood shavings) and yard trimmings (a mixture of grass clippings, leaves, and wood barks). Three piles with forced aeration were established by mixing 2:1 (v/v) ratio of poultry litter and yard trimmings. During composting, samples were taken at three different locations (top, middle, and bottom) of the forced aeration piles for microbial and enzyme analyses. Results demonstrated that population size of different microbial groups was not a limiting factor in this composting process as the microorganisms in the poultry litter + yard trimmings compost are in great abundance. Although the numbers of these microbial groups were reduced by high temperature, their populations multiplied rapidly as composting progressed. Fecal coliforms were eliminated by day 49, suggesting that the poultry litter + yard trimmings compost showed an overall increase in diversity and relative abundance of extracellular enzymes present as composting progressed. The population of fungi and actinomycetes (microorganisms active in degradation of cellulose, hemicellulose, and lignin) were positively correlated with esterase, valine amino-peptidase, α-galactosidase, β-glucosidase, and lipase. Of all 19 enzymes examined, ß-galactosidase (enzyme involved in the hydrolysis of lactose) had the most significant positive correlation with microbial populations, such as total aerobic heterotrophs, ammonium- and nitrite-oxidizing bacteria, denitrifying bacteria, and fecal coliforms. Cystine amino peptidase, chymotrypsin, and trypsin showed no evidence of activity during the entire period of composting. This composting process represented a combined activity of a wide succession of environments in the compost pile as one microbial group/enzyme overlapped the other and each emerged gradually as a result of the continual change in temperature as well as moisture content, O₂ and CO₂ level, and progressive breakdown of complex compounds to simpler ones.     

Evaluation of Organic Wastes for Composting

Management of organic wastes is essential to reduce environmental pollution and increase resources of plane nutrients for crop production. This study was undertaken to evaluate major organic wastes produced in northwestern Pakistan for characteristics that are useful for composting. Organic wastes such as manures, municipal wastes (MW), crop residues, fruit/vegetable wastes, and yard wastes contained large reserves of nutrients. Manures had high nitrogen (N) and crop residues had low N. Crop residues were relatively dry (7–12% moisture); MW, poultry manure, sheep manure, leaves, and city garbage were moderately moist (27–47% moisture), whereas cattle manure (CM), fruit and vegetable wastes, and grass clippings were wet (62–89% moisture). The compost developed from mixing MW with CM matured early and had low C/N ratio compared with either source alone. These results suggested that MW could be converted into compost when mixed with CM. The inoculation of wastes with effective microbes (EM) was ineffective in expediting the process of composting.     

Temperature and Chemical Changes During Composting of Broiler Litter

Composting broiler litter (a mixture of manure, bedding material, and wasted feed) with commonly available high-C substrates may be a viable alternative to reduce current land disposal practices for litter. Broiler litter with wood shavings as a bedding material and broiler litter with peanut hulls as a bedding material were composted with wheat straw, peanut hulls, pine bark and paper mill sludge in 0.33 m³ batch reactors. Litters and C substrates were mixed to achieve C:N ratios of approximately 30:1. Dry weight, total N, total C, temperature, electrical conductivity and pH were determined at regular intervals. Maximum temperatures peaked near 70°C within 2.25 d after mixing peanut hulls with litter and within 2.58 d for pine bark and litter. Composts made from paper mill sludge approached 50°C within 3.71 d. Wheat straw composts never exceeded 40°C which could present potential health problems associated with pathogenic microorganisms. Mass loss and C:N ratio gradually declined and stabilized approximately 84 d after mixing. Mass loss averaged 73 percent for wheat straw compost, 33 percent for peanut hull composts, and 16 percent for the other mixes. Wheat straw compost C:N ratios stabilized near 14:1 and other mixes remained above 20:1, indicating N limited conditions for complete composting. Compost pH was 5.8 after 84 d from pine bark composted with wood shaving litter and was significantly lower than pH from paper mill sludge compost with an average pH of 6.9 but similar to all other compost mixes (pH 6.7). Electrical conductivity ranged from 0.35 S m^?1 for paper mill sludge composted with wood shaving litter to 0.91 S m^?1 from wheat straw composted with peanut hull litter. Composting temperature varied considerably among C sources and all required at least 72 d of curing to stabilize the C:N ratio. Composts made from wheat straw were most effective for waste reduction but temperatures were below the 50°C level generally considered necessary to kill pathogens.     

Heat Inactivation of E. coli During Manure Composting

Contamination of food and water by microorganisms from animal manure has become an important issue in public health. Escherichia coli O157:H7 is one of several emerging pathogens of concern. In this research, we studied how the self-heating, thermophilic phase of composting influenced laboratory-grown vs. bovine-derived E. coli O157:H7 mortality, specifically the relationship between temperature, time at temperature, and pathogen survival. Composting experiments were conducted in laboratory-scale bioreactors operated in three temperature ranges: 40°C to 50°C, 50°C to 60°C, and greater than 60°C. We measured the effects of temperature and composting time on E. coli O157:H7 mortality. Laboratory-grown E. coli O157:H7, inoculated into the initial compost material, were not detected after approximately 300 degree days of heating. In several experiments where compost temperatures did not rise above 50°C, an initial decline of E. coli O157:H7 with subsequent regrowth was observed. E. coli O157:H7 in compost materials from infected cattle were not detected after approximately 180 degree days of heating. Numbers of total coliform bacteria declined with temperature similarly to those of E. coli O157: H7. The results of this research provide information for reducing or eliminating E. coli O157:H7 in animal wastes.     

添加剂在猪粪堆肥过程中的作用研究

添加剂是指为了加快堆肥进程和提高堆肥产品质量,在堆肥物料中加入的微生物、有机或无机物质。本文通过室内培养与室外堆肥试验,研究不同添加剂对猪粪发酵过程中臭味及氮素损失的影响。结果表明,使用本研究中所采用的添加剂与发酵工艺,可以减少猪粪发酵中氨的挥发、氮素损失与猪粪的恶臭。75%含水量的猪粪经过20d的发酵,可达基本腐熟程度。添加剂可以优化堆肥过程的环境条件,提高微生物活性;加快堆肥的腐熟;减少氮素损失,保持养分含量;调节堆肥中各种营养元素的含量,提高堆肥质量。     

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.     

Effects of Initial Total Solids on Composting of Raw Manure with Biogas Recovery

A batch anaerobic composting process was investigated to evaluate the potential for biogas recovery from animal manure under the worst scenario of high initial solids and non-well adapted microorganisms. The effects of composting time and initial total solids content on biogas recovery and reduction of solids during anaerobic digestion of swine, poultry and beef manure were studied. Volatile solids reductions averaged 10% or less over a 30-day period for all initial solids contents, which was considerably lower than expected. Reductions in VS increased slightly as initial solids content in the reactor decreased. Reductions in COD were somewhat higher than for VS. The pH values were fairly stable during the composting experiments and within the range suitable for anaerobic digestion. Decreases in TKN and ammonia nitrogen during the process were insignificant, and greater decreases were observed for lower initial solids content in the reactors. Cumulative biogas production increased with decreasing solids content in the reactor for all types of manure. For the lowest initial solids contents (12-14%), swine manure produced more biogas, but at the higher initial solids contents there was little difference among the manure types. Biogas yields were about 0.5 m³/kg VS consumed for the lowest solids contents; however, yields were only about 0.2 m³/kg VS consumed for the higher initial solids. Methane content of the biogas samples averaged 49%. Based on these results, it appears that adapting microbial populations in the high solids feedstock may obtain reasonable biogas production rates and VS reduction during anaerobic digestion. Although some differences in results among the three types of manure were noted, they were not large and likely would not be significant with adapted microbial populations.     

牛粪与秸秆协同好氧堆肥过程参数变化规律研究

利用玉米秸秆屑、稻草秸秆屑和牛粪为原料进行序批式好氧堆肥,对堆肥处理的过程参数的变化规律进行了研究。结果表明：2个处理的物料温度在50~54℃维持7 d以上,最终反应产物的无害化程度较高;最终剩余产物的氮、磷、钾相对含量都有所升高,达到了农用控制标准;处理过程中氮素均呈增加趋势;由于在好氧反应阶段存在不同程度的氮损失,因此在反应的后期阶段要注意采取保氮措施。     

Chemical Evaluation of Sewage Sludge Composting as a Mature Indicator for Composting Process

Several chemical parameters were studied during a 100 daysperiod in order to identify parameters that can be used asindicators of compost maturity. One treatment was a mixture ofsewage sludge and sawdust (TS); another was a mixture of sewagesludge, pig manure and sawdust (TS-PM). The pH of water extractsincreased during the thermophilic phase and then decreased in twotreatments. While the electrical conductivity (EC) decreasedthroughout the composting time. The 4.99% in the change ofvolatile matter of TS-PM was higher than 1.73% in that of TS,at the same time, the change of organic carbon were 5.04% inTS-PM more than 3.82% of TS. Total nitrogen content in TS andTS-PM had a markedly increase tendence during composting, andthe change in TS-PM was very more obvious than in TS, soreduction of C/N ratio in TS-PM was higher than in TS, C/Nratio of TS-PM and TS was 14.39 and 18.57 in mature production,respectively. Carbon content in HA plus FA and HA in twocomposts decreased from 0 to 100 day, but carbon content of FAdecreased, so HA-C/FA-C ratio, HR, HI has a markedly increase inTS and TS-PM, and the parameters in TS-PM were higher than inTS. The points expressing maturity degree in TS-PM was more inTS. The nitrogen content of HA plus and HA showed a increasedtendence in TS and TS-PM, the change of nitrogen of thesefractions in TS-PM was higher than in TS, so C/N ratio of allfractions including HA plus FA, HA and FA, indicated a reductiontendence, and the refuction in FA was larger than in HA. E4/E6ratio of HA plus FA and HA decreased during composting, and one FA was increase. E4/E6 ratio of HA plus FA and HA in TS-PM wasvery smaller than in TS, HA in TS-PM was a larger molecular sizethan HA in TS. The changes of organic matter compositions incomposting: the crude fat and carbohydrates had a markedlyreduction and cellulose plus hemicellulose had a slight decrease;crude protein and lignin content in TS and TS-PM had an increasetendence.     

MSW Compost Reduces Nitrogen Volatilization During Dairy Manure Composting

Manures lose N through volatilization almost immediately after deposit. Attempts to control losses include the addition of a C source to stimulate nitrogen immobilization. Composting is a treatment process that recommends the addition of carbonaceous materials to achieve a C:N ratio of 30:1 to stimulate degradation and immobilize nitrogen. Dairies near cities may be able to reduce N loss from manures by composting with urban carbonaceous residues such as municipal solid waste (MSW) or MSW compost that, by themselves, have little agronomic value. Studies were conducted using a self-heating laboratory composter where dairy solids were mixed with MSW compost to determine the reduction of N loss during composting. One-to-one mixtures (v/v) of dairy manure solids and MSW compost were composted and NH₃ volatilization, CO₂ evolution and temperatures were compared to composting of manure alone. Addition of MSW compost resulted in increased CO₂ evolution and reduced N loss. Nitrogen loss from composting dairy manure alone was four to ten times greater than that from composting dairy manure mixed with MSW compost. Adjustment of the C:N ratio to 25 by adding MSW compost to manure appeared to be the major factor in reducing N losses.     

Survival of Lab Grown Calonectria pseudonaviculata Microsclerotia During Small-Scale Composting

Boxwood blight, caused by Calonectria pseudonaviculata, is a devastating fungal disease of Buxus spp., first observed in the United States in 2011. Due to the persistent nature of the produced microsclerotia, concern arose over the potential for compost to serve as a disease vector. Previous work demonstrated that C. pseudonaviculata is very stable at mesophilic temperatures, however, no previous work has evaluated C. pseudonaviculata during composting. Our objective was to evaluate the survival of C. pseudonaviculata microsclerotia after being composted for 24, 48, and 72?h at temperatures of 40, 50, and 60?°C. Composting was performed using a newly created bioreactor system, allowing for precise control of the composting process. In conjunction with the composting evaluations, the same temperature/time combinations were evaluated in incubators. While the pathogen survived 40?°C through 72?h in an incubator, compost survival was minimal, with only some survival observed at 24?h at the same temperature. We were able to determine that exposure to temperatures ≥50?°C for 24?h or longer, and that exposure in a composting system for 48?h or longer at 40?°C would kill the microsclerotia.     

Changes in Concentrations of Malodorous Compounds During Controlled Aeration Composting

Effects of composting on odorous chemicals in dairy manure were investigated in replicated pilot-scale studies. Three 16-day composting trials were conducted, using 205 L vessels containing 83 kg mass. Fresh or 12-day-aged manure, from lactating cows, was mixed with sawdust (3man:1saw w/w). Vessels were either aerated continuously with high (2.3 kg/hr)/low (0.8 kg/hr) air flow controlled by thermostats or intermittently on a 5 min high air flow/55 min off clock controlled cycle. Six vessel replicates were conducted on each manure/air flow treatment combination. Temperatures, air flow, O₂ consumption, and CO₂ production were recorded every 10 minutes. Trapped NH₃ emissions were determined daily. Exhaust air was passed through water-cooled condensers to analyze emitted volatiles, and condensate volume, pH, and volatile fatty acids (VFAs) were quantified at 12 or 24 hour intervals. Solids were collected from each vessel initially, at remix at the end of day 7, and at the end of each trial (day 16) for analysis of moisture, pH, ash, C/N, and odorants. Phenolics and indolics were extracted with ethyl ether. VFAs were recovered with pH 2.0 water. Analysis was by flame or mass selective detection gas chromatography. Temperature increased most rapidly in continuously aerated vessels yet maintained a lower mean temperature (49 vs 58°C) than intermittent aeration. Both returned to near ambient temperature by day 16. Continuous aeration nearly doubled (11 vs 18 L) the amount of condensate released over 16 days. Fresh manure/sawdust mixes contained 6553, 795, 77, 51, 19, and 17μg/g of acetate, propionate, isobutyrate, isovalerate, phenol, and p-cresol. Aged manure mixes contained 9350, 3397, 2810, 445, 285, 441, 34, 176, and 18 μg/g acetate, propionate, butyrate, valerate, isobutyrate, isovalerate, phenol, p-cresol, and skatole, as well as a number of C₁₁ to C₁₇ fatty acids. Both aeration methods maintained conditions that resulted in the destruction of most of the odorous chemicals studied in the composting mass in 7 days with only small quantities of acetate, isobutyrate, and skatole present by the end of day 16. Continuous aeration, as opposed to intermittent, more than doubled (115 vs 55 g) the emissions of NH3-N and increased the emissions of VFAs in condensate four-fold. Whereas, limited aeration did not destroy the odorants as rapidly, they remained in the compost until destruction.     

Structural Changes of Humic Acids During Olive Mill Pomace Composting

The aim of this work was to characterize the humic acids during composting using both chemical and spectroscopic analytical methods. Humic acids (HA) were extracted from olive mill pomace (OMP) after 5, 10, 21, 32, 48, 60, 84, 95, 109 and 153 days of composting and their elemental composition, functional groups, molecular weight, ¹³C CP-MAS NMR and FTIR spectra were determined. Elemental composition of HA showed a decrease of carbon content from 56.8% to 47.1% and an increase of oxygen content from 32.7 % to 43.3%. A slight increase of carboxylic groups was observed with no variation of phenolic groups. The molecular weight of HA determined by gel chromatography showed that after 95 days of composting the molecular weight of about 40% of the polymers was greater than 10² KDalton. The ¹³C CPMAS NMR and FTIR spectra of HA showed compositional and structural changes indicating a slight increase of polysaccharides and aromatic groups and a decrease of long aliphatic chains during the composting.