Laboratory study of inocula production for composting processes

Six ligno-cellulolytic fungi were tested regarding to examine their capability to grow on agricultural wastes and produce inocula for composting. Two residues were used: pepper plant wastes and almond shell residues. Results showed the latter as the most adequate substrate for growth of fungi tested. On the contrary, Trichoderma koningii, as well as HLC1 and HLC3, both fungi isolated from almond shell wastes, were able to persist in pepper plant wastes. Modifications of aeration and pH significantly influenced growth of Coriolus versicolor, HLC1 and Phanerochaete. flavido alba and P. flavido alba and Phlebia radiata, respectively, while P. flavido alba was the only microorganism whose growth was not significantly altered by temperature. In competitive assays, where fungi were growth together with other species, growth of both microorganisms isolated from almond shell residues, HLC1 and HLC3, were stimulated while T. koningii showed the better results in sterile conditions.     

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.     

Influence of green waste, biowaste and paper-cardboard initial ratios on organic matter transformations during composting

The influence of green waste, biowaste and paper-cardboard proportions in initial mixtures on organic matter (OM) evolution during composting in pilot-scale reactors was studied using respirometric procedure, humic substance extraction, crude fiber analysis and Fourier transform infrared spectroscopy. The stabilisation of OM during composting resulted from the degradation of easily biodegradable organic fraction as cellulose and hemicellulose, the relative increase of resistant compounds as lignin, the microbial synthesis of resistant biomolecules, and from humification processes. Little stabilisation of green waste OM during composting was observed, in relation with their large lignin content. With moderate contents of paper-cardboard in initial mixtures (20-40%), cellulose proportion remained favorable to fast OM stabilisation. Larger proportions of paper-cardboard (more than 50%) affected OM stabilisation, probably due to a lack of nitrogen. The influence of biowastes only appeared at the very beginning of composting, because of their large proportions of easily biodegradable OM.     

Extracellular enzyme activities during humic acid degradation by the white rot fungi Phanerochaete chrysosporium and Trametes versicolor

Abstract The relationship between humic acid biodegradation and extracellular lignin peroxidase and Mn-dependent peroxidase activities of two white rot fungi, Phanerochaete chrysosporium and Tranetes versicolor , reported to be lignin degraders, was examined. In experimental conditions promoting culture aeration, particularly with T. versicolor no extracellular peroxidase activity could be detected unless humic acids were included in the culture medium. In the presence of humic acids, appreciable enzymatic activities were determined in the culture filtrate of the two fungi. However, T. versicolor was a more effective degrader than P. chrysosporium , and mineralization assays on synthetic humic acids with culture filtrates showed the important role played by Mn²⁺. The surfactant properties of humic acids are suggested to be responsible for the increase of enzymatic activities.     

In vitro Studies on lignocellulose degradation by microbial strains isolated from composting processes

An in vitro study of different strains isolated from composting piles in relation to their capacity to biodegrade lignocellulose was achieved. Thirteen microorganisms (five bacteria, one actinomycete, and seven fungi) isolated from compost windrows were grown on agricultural wastes and analyzed for cellulose, hemicellulose, and lignin degradation. Hemicellulose fraction was degraded to a lesser extent because only two of the isolates, B122 and B541, identified as Bacillus licheniformis and Brevibacillus parabrevis, respectively, were able to decrease the concentration of this polymer. On the contrary, most of the isolates were capable of reducing cellulose and lignin concentrations; strain B541 was the most active cellulose degrader (51%), while isolate B122 showed higher lignin degradation activity (68%). Consequently, an increase in humification indices was detected, especially with respect to humification index (HI) for both bacteria and CAH/AF in the case of strain B122. According to these data, the use of microbial inoculants as a tool to improve organic matter biodegradation processes (i.e., composting) may become important if microorganisms’ capabilities are in accordance with the final characteristics required in the product (high humic content, lignin content decrease, cellulose concentration decrease, etc.).     

Evaluation of “alperujo” composting based on organic matter degradation, humification and compost quality

The main by-product generated by the Spanish olive oil industry, a wet solid lignocellulosic material called "alperujo" (AL), was evaluated as a composting substrate by using different aeration strategies and bulking agents. The experiments showed that composting performance was mainly influenced by the type of bulking agent added, and by the number of mechanical turnings. The bulking agents tested in this study were cotton waste, grape stalk, a fresh cow bedding and olive leaf; the latter showed the worse performance. Forced ventilation alone was revealed to work inadequately in most of the experiments. The composting process involved a substantial degradation of the organic substrate with average losses of 48.4, 28.6, 53.7 and 57.0% for total organic matter, lignin, cellulose and hemicellulose, respectively. Both organic matter biodegradation and humification were greatly influenced by the lignocellulosic nature of the starting material, which led to low organic matter and nitrogen loss rates and a progressive increase in more humified substances, as revealed by the end-values of the humification indices. The resulting composts were of good quality in terms of nutrient content, stabilised and non-phytotoxic organic matter and low heavy metal content. This demonstrates that composting technology can be used as an alternative treatment method to turn AL into compost that can be used as organic amendments or fertilisers for agricultural systems.     

Olive mill waste composting: A review

Olive mill wastes exacerbate environmental problems in Mediterranean countries. These wastes are highly phytotoxic and contain phenolic compounds, lipids and organic acids. They also contain high percentages of organic matter and a vast range of plant nutrients that could be reused as fertilizers for sustainable agricultural practices. In this paper, recent research on composting wastes of 2-phase and 3-phase olive mills is reviewed, concentrating on factors affecting composting such as bulking agents, aeration strategy, physicochemical characteristics (duration of the thermophilic phase, moisture content, organic matter, volatile solids, total organic carbon, water soluble carbon, total nitrogen, total phosphorus, potassium, C/N ratio, phenols and the humification process), and phytotoxicity. The review highlights the effects of composting operational factors (bulking agent, additives, and aeration strategy) on the physicochemical characteristics of the final compost, and the production of a good quality soil amender or fertilizer.     

Performance characteristics of three aeration systems in the swine manure composting

Pilot composting of swine manure mixed with rice straw was carried out to evaluate performance characteristics of three aeration systems: forced aeration, passive aeration and natural aeration. It was expected to provide academic basis for farmers to select an advisable aeration system. The results showed that the thermophilic durations were long enough to satisfy the sanitary standard, and swine manure could reach maturity. The indexes of the composting, including physical changes, pH value, TOC, OM, TKN, WSC, WSN, solid C/N ratio, water-soluble C/N ratio, TOM, NH4+-N, (NO3(-) + NO2(-))-N, and GI had no significant difference among the treatments (P > 0.05) except the average temperature profiles (P12 = 0.001, P13 = 0.036). Economic analysis showed that a passive aeration system was suitable for a small-scale swine farm, and forced aeration system should be considered to apply in the middle and large-scale swine farms with a high extent of industrialization. But, in order to avoid too high temperature occurring during composting, an active aeration control system needed to be developed.     

Effect of inoculating white-rot fungus during different phases on the compost maturity of agricultural wastes

The lignocellulolytic microorganism, Phanerochaete chrysosporium, was inoculated during different phases of agricultural wastes composting, and its effect on compost maturity was studied. In the three runs, the decrease in C/N ratio and increases in germination index and humification indices (humification ratio, humification index, percentage of humic acids and degree of polymerisation) were found. Furthermore, the different effects of inoculation during different phases on the compost maturity could be observed by using ANOVA. When inoculated during the second fermentation phase, P. chrysosporium induced significant changes on all parameters of compost maturity except C/N ratio, whereas it did not produce an obvious change on these parameters when inoculated during the first fermentation phase.     

Two-phase olive mill waste composting: enhancement of the composting rate and compost quality by grape stalks addition

Two-phase olive mill waste (TPOMW) is a semisolid sludge generated by the olive oil industry. Its recycling as a soil amendment, either unprocessed or composted, is being promoted as a beneficial agricultural practice in the Mediterranean area. One of the major difficulties when composting TPOMW is the compaction of the material due to its dough-like texture, which leads to an inadequate aeration. For this reason, the addition of bulking agents is particularly important to attain a proper composting process. In this study we followed the evolution of two composting mixtures (A and B) prepared by mixing equal amounts of TPOMW and sheep litter (SL) (in a dry weight basis). In pile B grape stalks (GS) were added (10% dry weight) as bulking agent to study their effect on the development of the composting process and the final compost quality. The incorporation of grape stalks to the composting mixture changed the organic matter (OM) degradation dynamics and notably reduced the total amount of lixiviates. The evolution of several maturation indices (C/N, germination index, water soluble carbon, humification indices, C/N in the leachates) showed a faster and improved composting process when GS were added. Moreover, chemical (NH₄ ⁺, NO₃ ⁻, cation exchange capacity, macro and micronutrients, heavy metals) and physical properties (bulk and real densities, air content, total water holding capacity, porosity) of the final composts were analysed and confirmed the superior quality of the compost where GS were added.     

生物垃圾堆肥的过程研究及腐熟度评价

目的：研究静态强制通风发酵工艺对合肥市农贸市场的生物废弃物进行好氧堆肥处理过程的物质变化和腐熟效果。方法：分析发酵过程中温度、含水率、挥发分含量、纤维素、半纤维素和木质素含量等物理指标和化学指标。结果：一次发酵中堆肥的温度在55℃以上的有3d,经过一次发酵和二次发酵,堆肥中挥发分含量由85.4%降低到51.2%。纤维素的含量由20.90%减少到15.48%,半纤维素的含量由7.20%减少到1.36%,,纤维素、半纤维素在二次发酵中降解率比一次发酵的小,木质素虽在一次发酵中基本没有降解。但在二次发酵中得到有效降解,木质素含量由8.30%减少到5.38%。堆肥后物料在70d堆肥后,基本上达到腐熟程度。结论：温度、含水率、挥发性物质、淀粉实验、生物可降解度实验等指标检测可以评价静态强制通风发酵工艺对合肥市农贸市场的生物废弃物进行好氧堆肥处理过程的物质变化和腐熟效果。     

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.     

Determination of aeration rate and kinetics of composting some agricultural wastes

This study aimed to determine the aeration rate and its kinetics in aerobic composting of agricultural wastes. For this aim compost materials were prepared by mixing grass trimmings, tomato, pepper, and eggplant wastes. Four vertical forced aeration type reactors and one vertical natural convection type reactor were manufactured to apply four different aeration rates. CO2 rate and temperature changes were recorded in three different places in the reactors. Moisture content, pH and organic material rate were recorded each day. While process-monitoring parameters (CO2, temperature, pH, moisture content) were used for interpretation of the process, organic material degradation was used for interpretation of the process success. The seven different kinetic models were applied for modeling decomposition rate to the experimental values. According to the results, four of these models were found applicable to this study. These models were analyzed with some statistical methods as root mean square error (RMSE), chi-square (chi2), and modeling efficiency (EF). According to the statistical results of these models, the best model was found as: [Formula: see text] where kT is the rate of decomposition (g VS/g VS day); T the process temperature (degrees C); Mc the daily moisture content (%wb); C the daily CO2 rate in composting reactor (%) and a, b, c, d are constants. According to the results, the highest organic matter degradation and temperature value were obtained at the aeration rate of 0.4 l air min(-1)kg(om)(-1). Thus, it could be applied to this mixed materials composting process.     

Olive oil mill waste waters decoloration and detoxification in a bioreactor by the white rot fungus Phanerochaete flavido-alba

Olive oil mill wastewater (OMW) is produced as waste in olive oil extraction. With the purpose of treating this highly polluting waste, a number of experiments were conducted in a laboratory-scale bioreactor with the white rot fungus Phanerochaete flavido-alba (P. flavido-alba). It is known that this fungus is capable of decolorizing OMW in static or semistatic cultures at Erlenmeyer scale and at 30 degrees C. The objective of this work was to prove that P. flavido-alba could decolorize OMW in submerged cultures and that it is capable of reducing OMW toxicity at room temperature (25 degrees C) and in a laboratory-scale bioreactor. In the experiments conducted, manganese peroxidase (MnP) and laccase enzymes were detected; however, unlike other studies, lignin peroxidase was not found to be present. Decoloration obtained after treatment was 70%. The reduction of aromatic compounds obtained was 51%, and the toxicity of the culture medium was reduced by up to 70%. We can therefore state that P. flavido-alba is capable of reducing important environmental parameters of industrial effluents and that prospects are positive for the use of this process at a larger scale, even when working at room temperature.     

Microbial community succession and lignocellulose degradation during agricultural waste composting

The changes of microbial community during agricultural waste composting were successfully studied by quinone profiles. Mesophilic bacteria indicated by MK-7 and mesophilic fungi containing Q-9 as major quinone were predominant and seemed to be important during the initial stage of composting. Actinobacteria indicated by a series of partially saturated and long-chain menaquinones were preponderant during the thermophilic period. While Actinobacteria, fungi and some bacteria, especially those microbes containing MK-7(H4) found in Gram-positive bacteria with a low G+C content or Actinobacteria were found cooperate during the latter maturating period. Since lignocellulsoe is abundant in the agricultural wastes and its degradation is essential for the operation of composting, it’s important to establish the correlation between the quinone profiles changes and lignocellulose degradation. The microbes containing Q-9 or Q-10(H2) as major quinone were found to be the most important hemicellulose and cellulose degrading microorganisms during composting. While the microorganisms containing Q-9(H2) as major quinone and many thermophilic Actinobacteria were believed to be responsible for lignin degradation during agricultural waste composting.     

彩绒革盖菌在猪粪堆肥中应用的初步研究

在以猪粪为原料的静态条垛堆肥的堆体试验中添加了彩绒革盖菌,研究其对堆肥发酵的影响。研究表明彩绒革盖菌在堆肥二次发酵时期有利于堆体温度的提升和保温,说明了在进入堆肥后期彩绒革盖菌对其中剩余的木质素等成分有很好的分解能力,有利于堆肥的腐熟和养分的释放,初步表明彩绒革盖菌是一株理想的堆肥发酵菌株。     

Study of lignin biotransformation by Aspergillus fumigatus and white-rot fungi using (14)C-labeled and unlabeled kraft lignins

The biodegradation of lignin by fungi was studied in shake flasks using (14)C-labeled kraft lignin and in a deep-tank fermentor using unlabeled kraft lignin. Among the fungi screened, A. fumigatus-isolated in our laboratories-was most potent in lignin biotransformation. Dialysis-type fermentation, designed to study possible accumulation of low MW lignin-derived products, showed no such accumulation. Recalcitrant carbohydrates like mi-crocrystalline cellulose supported higher lignolytic activity than easily metabolized carbohydrates like cellobiose. An assay developed to distinguish between CO(2) evolved from lignin and carbohydrate substrates demonstrated no stoichiometric correlation between the metabolism of the two cosubstrates. The submerged fermentations with unlabeled lignin are difficult to monitor since chemical assays do not give accurate and true results. Lignolytic efficiencies that allowed monitoring of such fermentations were defined. Degraded lignins were analyzed for structural modifications. A. fumigatus was clearly superior to C. versicolor in all aspects of lignin degradation; A. fumigatus brought about substantial demethoxylation and dehydroxylation, whereas C. versicolor degraded lignins closely resembled undegraded kraft lignin. There was a good agreement among the different indices of lignin degradation, namely, (14)CO evolution, OCH(3) loss, OH loss, and monomer and dimer yield after permanganate oxidation.     

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.     

Radiation and fermentation treatment of cellulosic wastes

The effect of radiation pasteurization of sugar cane bagasse and rice straw and fermentation using various strains of fungi were studied for upgrading of cellulosic wastes. The initial contamination by fungi and aerobic bacteria both in bagasse and straw was high. The doses of 30 kGy for sterilization and 8 kGy for elimination of fungi were required. Irradiation effect showed that rice straw contained comparatively radioresistant microorganisms. It was observed that all the fungi (Hericium erinacium, Pleurotus djamor, Ganoderma lucidum, Auricularia auricula, Lentinus sajor-caju, Coriolus versicolor, Polyporus arcularius, Coprinus cinereus) grow extending over the entire substrates during one month after inoculation in irradiated bagasse and rice straw with 3% rice bran and 65% moisture content incubated at 30°C. Initially, sugar cane bagasse and rice straw substrates contained 39.4% and 25.9% of cellulose, 22.9% and 26.9% of hemicellulose, and 19.6% and 13.9% of lignin + cutin, respectively. Neutral detergent fibre (NDF) values decreased significantly in sugar cane bagasse fermented byG. lucidum, A. auricula andP. arcularius, and in rice straw fermented by all the 8 strains of fungi. Acid detergent fibre (ADF) values also decreased in bagasse and rice straw fermented by all the fungi.P. arcularius, H. erinacium, G. lucidum andC. cinereus were found to be the most effective strains for delignification of sugar cane bagasse.     

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.