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.     

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.     

Biodegradation of olive husk mixed with other agricultural wastes

In this study, the evolution of the most important parameters (temperature, pH, electrical conductivity, total organic carbon, total nitrogen, and C/N ratio) describing the composting process of olive oil husk with other organic wastes was investigated. Four windrows for obtaining two mixed wastes composts (MWCs) and two green wastes composts (GWCs) were prepared.     

Shotgun metagenomics evaluation of soil fertilization effect on the rhizosphere viral community of maize plants

The need for sustainability in food supply has led to progressive increase in soil nutrient enrichment. Fertilizer application effects both biological and abiotic processes in the soil, of which the bacterial community that support viral multiplication are equally influenced. Nevertheless, little is known on the effect of soil fertilization on the Soil viral community composition and dynamics. In this study, we evaluated the influence of soil fertilization on the maize rhizosphere viral community growing in Luvisolic soil. The highest abundance of bacteriophages were detected in soil treated with 8 tons/ha compost manure (Cp8), 60 kg/ha inorganic fertilizer (N1), 4 tons/ha compost manure (Cp4) and the unfertilized control (Cn0). Our result showed higher relative abundance of Myoviridae, Podoviridae and Siphoviridae in 8 tons/ha organic manure (Cp8) fertilized compared to others. While Inoviridae and Microviridae were the most relative abundant phage families in 4 tons/ha organic manure (Cp4) fertilized soil. This demonstrate that soil fertilization with organic manure increases the abundance and diversity of viruses in the soil due to its soil conditioning effects.

     

Respirometric screening of several types of manure and mixtures intended for composting

The viability of mixtures from manure and agricultural wastes as composting sources were systematically studied using a physicochemical and biological characterization. The combination of different parameters such as C:N ratio, free air space (FAS) and moisture content can help in the formulation of the mixtures. Nevertheless, the composting process may be challenging, particularly at industrial scales. The results of this study suggest that if the respirometric potential is known, it is possible to predict the behaviour of a full scale composting process. Respiration indices can be used as a tool for determining the suitability of composting as applied to manure and complementary wastes. Accordingly, manure and agricultural wastes with a high potential for composting and some proposed mixtures have been characterized in terms of respiration activity. Specifically, the potential of samples to be composted has been determined by means of the oxygen uptake rate (OUR) and the dynamic respirometric index (DRI). During this study, four of these mixtures were composted at full scale in a system consisting of a confined pile with forced aeration. The biological activity was monitored by means of the oxygen uptake rate inside the material (OURinsitu). This new parameter represents the real activity of the process. The comparison between the potential respirometric activities at laboratory scale with the in situ respirometric activity observed at full scale may be a useful tool in the design and optimization of composting systems for manure and other organic agricultural wastes.     

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.     

Modelling the change in soil organic C and N and the mineralization of N from soil in response to applications of slurry manure

A computer simulation model of the turnover of organic matter in soil was adapted to simulate the change in soil organic C and N contents of soil during several years following annual additions of farm slurry to maize fields. The model proved successful in estimating the build-up of both C and N in soil and the leaching of N to ground-water in response to applications of slurry ranging from 50 to 300 tons per hectare per year. The model was then used to estimate the build-up of organic matter in soil under crops of fodder maize that were grown using the excess of manure produced during the last 20 years in the Netherlands. The build-up of organic matter from these applications was estimated to lead to about 70 kg extra nitrogen mineralized ha^-1 yr^-1. As a result of legislation manure applications have decreased and are expected to decrease further in the immediate future. Calculations suggest that after 10 years of manure applied at rates no longer exceeding the amount needed to replace the phosphorus removed by crops, the extra mineralization of N will still be between 45 and 60 kg ha^-1 yr^-1. If manure applications cease altogether then the extra mineralization will be about 25–30 kg N ha^-1 yr^-1.     

Composting of high moisture content swine manure with corncob in a pilot-scale aerated static bin system

Pilot composting experiments of swine manure with corncob were conducted to evaluate the performance of the aerated static bin composting system. Effects of temperature control (60 and 70 degrees C) and moisture content (70% and 80%) were monitored on the composting by measuring physical and chemical indexes. The results showed that (1) the composting system could destroy pathogens, converted nitrogen from unstable ammonia to stable organic forms, and reduced the volume of waste; (2) significant difference of NH(4)(+)-N (P(12) = 0.074), and (NO(3)(-) + NO(2)(-))-N (P(12) = 0.085) was found between the temperature control treatments; (3) anaerobic reaction in the treatment with 80% moisture content resulted in significant difference of pH (P(23) = 0.006), total organic matter (P(23) = 0.003), and germination index (P(23) = 0.040) between 70% and 80%. Therefore, the optimum initial moisture content was less than 80% with the composting of swine manure and corncob by using the composting system.     

Transformation of buffalo manure by composting or vermicomposting to rehabilitate degraded tropical soils

The addition of composted buffalo manure may lead to qualitative and quantitative improvement of the organic matter content of degraded tropical agricultural soils in Northern Vietnam. The objectives of this study were to follow the biochemical changes occurring during composting of buffalo manure with and without earthworms during 3 months and to study the effect of the end products (compost and vermicompost) on soil biochemical parameters and plant growth after two months of incubation under controlled conditions in an open pot experiment. Our conceptual approach included characterisation of organic matter of the two composts before and after addition to soil by elemental, isotopic analysis and analytical pyrolysis and comparison with conventional fertilisation. We also analysed for lignin content and composition.Our results showed that composting in the presence of earthworms led to stronger transformation of buffalo manure than regular composting. Vermicompost was enriched in N-containing compounds and depleted in polysaccharides. It further contained stronger modified lignin compared to regular compost. In the bulk soil, the amendment of compost and vermicompost led to significant modification of the soil organic matter after 2 months of exposure to natural weather conditions. The lignin component of SOM was unaffected whatever the origin of the organic amendment. Compost and vermicompost amendments both enhanced aggregation and increased the amount of organic matter in water stable aggregates. However, vermicompost is preferable to compost due to its beneficial effect on plant growth, while having similar positive effects on quantity and quality of SOM.     

Co-Composting of Residual Fuel Contamination in Soil

A remediation program was designed and implemented at a site in southeastern Australia that had become contaminated with nonvolatile, n-alkane total petroleum hydrocarbons (TPH). The remediation was conducted in two stages. The excavation, validation and reinstatement of two contaminated areas on the site was first conducted, followed by development of a composting treatment process. The total volume of contaminated soil (i. e., TPH concentration >1000?mg/kg C₁₀?C₃₆) was ～4300?m³ with a concentration of 3100±1270?mg/kg. The soil was stockpiled into four windrows, on a compacted, bunded clay base. Approximately 35% (v/v) of raw materials (green tree waste, cow manure, gypsum, and nutrients) were added to initiate composting. The piles were kept moist during the summer months, but no other maintenance was conducted. Once the composting process was initiated, the windrows were sampled at 2 and 6 months. After 6 months treatment, the average TPH concentration (C₁₀?C₃₆) was 730?mg/kg (with a 95% CI of 1020?mg/kg), which met the relevant clean fill criteria applicable to the site. There were no other contaminants of significance in the treated soil compost and it posed no unacceptable risk to human health or the environment, allowing it to be used as fill at the site.     

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).     

Effects of pulp mill solids and three composts on early growth of tomatoes

Compost has been proposed as a means of simultaneously diverting organic materials from landfills while producing a valuable product that improves tilth, organic matter content and nutrient supply of agricultural soils. Composts manufactured from different source materials may have markedly different properties however, even if they meet all regulatory requirements. We compared the capacity of composts made from three different combinations of organic wastes (horse manure and bedding, mink farm wastes, municipal solid waste (MSW) and sewage sludge) along with clarifier solids from a chemo-thermomechanical pulp mill, to enhance the growth of tomato (Lycopersicon esculentum L.) seedlings grown in nutrient-poor organic potting soil. Germination and seedling emergence of tomatoes, cress (Lapidium sativum L.) or radish (Raphanus sativus L.) were tested to assess phytotoxicity of the four amendments. Mink farm compost and horse manure compost stimulated root and shoot growth of tomato seedlings but MSW compost and pulp mill solids were strongly inhibitory. MSW compost and unamended potting soil also inhibited seedling emergence and pulp mill solids produced stunting and deformities in radish and cress seedlings. Both toxic constituents and nutrient imbalances may be responsible for the growth-inhibiting effects of these amendments. Application of pulp mill solids to agricultural soil without composting may lead to deleterious effects on vegetable crops.     

Monitoring of microbial populations and their cellulolytic activities during the composting of municipal solid wastes

Seasonal changes in microbial populations and the activities of cellulolytic enzymes were investigated during the composting of municipal solid wastes at Damietta compost plant, Egypt. The changes in temperature, pH and carbon/nitrogen (C/N) ratio were also monitored. The results obtained showed that the temperatures of the windrows in all seasons reached the maximum after 3 weeks of composting and then decreased by the end of the composting period (35 days), but did not reach ambient temperature. Marked changes in pH values of the composts in all seasons were found, but generally, the pH was near neutrality. Significant increases in the size of the microbial populations were obtained in autumn and spring seasons compared to summer and winter seasons. The activities of cellulases were also higher in the autumn and spring seasons than in the summer and winter seasons. The decrease in C/N ratio in autumn and spring was higher than in summer and winter. It was evident that the degradation of organic matter increased by an increase in the microflora and its cellulolytic activities.     

不同有机废弃物改良新复垦耕地的综合效果评价

由废弃地整理复垦形成的耕地存在土壤有机质和有效养分低、土壤板结、微生物活性弱和土壤耕作性状不良等问题,快速、有效地提高土壤肥力质量是全面提升该类耕地质量和生产性能的重要组成部分.本文通过田间小区试验研究了城郊有机废弃物对新复垦耕地土壤培肥的综合效果,并比较了不同类型城郊有机废弃物在培育耕地质量方面的差异.试验设置了施用等量猪粪、鸡粪、水稻秸秆、蔬菜收获残留物、城市污泥、沼渣、猪粪/水稻秸秆堆肥、生活垃圾堆肥和对照（不施有机肥）9个处理（年用量30 t·hm^-2）,连续进行3年的定点试验.结果表明： 施用任何有机物对改善土壤肥力均有明显的作用.其中,提升土壤碳库管理指数以施用猪粪、鸡粪、猪粪/水稻秸秆堆肥、水稻秸秆和沼渣的效果最为显著;增加土壤水稳定性团聚体和降低土壤容重以施用猪粪/水稻秸秆堆肥和沼渣的效果最佳;施用污泥、猪粪/水稻秸秆堆肥和生活垃圾堆肥可增强土壤保蓄能力;施用猪粪、鸡粪和猪粪/水稻秸秆堆肥对增加土壤有效态养分的效果最为明显;各类有机物均显著提高了土壤微生物数量和酶活性.长期施用污泥、生活垃圾堆肥及畜禽粪存在着土壤重金属污染的风险,但短期施用对土壤环境质量影响不明显.总体上,对土壤肥力的改善效果由大至小依次为：猪粪/水稻秸秆堆肥>鸡粪>猪粪>沼渣>生活垃圾堆肥>水稻秸秆>城市污泥>蔬菜收获残留物;对土壤的相对污染程度由大至小为：城市污泥>生活垃圾堆肥>猪粪>鸡粪>沼渣>猪粪/水稻秸秆堆肥>蔬菜收获残留物>水稻秸秆.     

Changes in functional abilities of the microbial community during composting of manure

The objective of this study was (a) to detect changes of the functional abilities of the microflora during composting of manure as a result of windrow turning frequency and (b) to detect differences between distinct zones within the windrows. Biolog GN microtiter plates containing 95 different carbon sources were inoculated with diluted suspensions of compost material containing 15,000 microorganisms per well (120 l). We found a dramatic shift in functional microbial community structure during the 8-week composting process. The shift was more rapid when the compost windrows were turned. The substrate use pattern in the outer, well-aerated zone of the unturned windrow was similar to that of the turned windrows. Microbial biomass and respiration decreased more rapidly in the turned than in the unturned windrows, indicating a different pace of compost maturation. The data suggest that the Biolog assay may be a suitable approach to determine compost maturity. Correspondence to: H. Insam     

Effects of age of cattle,turning technology and compost environment on disappearance of bone from mortality compost

As residual bones in mortality compost negatively impact subsequent tillage, two studies were performed. For the first study, windrows of mature cattle or calves were placed on a base of barley straw and covered with beef manure. Windrows were divided into two sections and turned at 3-month intervals. Approximately 5000 kg of finished compost per windrow was passed through a 6 mm trommel screen, with bones collected and weighed. Bone weight was 0.66% of mature cattle compost and 0.38% of calf compost on a dry matter basis, but did not differ after adjustment for weights of compost ingredients. In a subsequent study, four windrows were constructed containing mortalities, straw and beef manure (STATC) or straw, manure and slaughter waste (STATW). Also, straw, beef manure and slaughter waste was added to an 850 L rolling drum composter (DRUMW). Fresh bovine long-bones from calves were collected, weighed and embedded in the compost. Bones were retrieved and weighed when windrows were turned, or with DRUMW, after 8 weeks. Temperatures achieved followed the order STATW > STATC > DRUMW (p < 0.05). Rate of bone disappearance followed a pattern identical to temperature, with the weight of bones in STATW declining by 53.7% during 7 weeks of composting. For STATC, temperatures were uniform over three composting periods, but bone disappearance was improved (p < 0.05) when compost dry matter was lower (46%), as compared to 58%. Using a ratio of five parts manure to one part mortalities, results of this study demonstrated that residual bone was <1% of cured cattle compost and may be reduced by maintaining a high compost temperature and moisture content.     

Influence of straw types and nitrogen sources on mushroom composting emissions and compost productivity

The effects of different straw types and organic and inorganic nitrogen (N) sources on the chemical composition and odor concentration (OC) of mushroom composting emissions, compost parameters, and mushroom yield were examined using bench-scale and large-scale (windrows and aerated tunnels) composting systems. There were close correlations between the butanol or combined H₂S+dimethyl sulfide (DMS) concentration and OC of air samples taken from different composting ingredients (r=0.83 and 0.76–0.87, P<0.01, for log_e-transformed data). Differences in N availability, in terms of NH₃ and N losses during composting, were found between different N sources. Materials in which the N was less available (chipboard and digester wastes, cocoa shells, ammonium sulfate) produced lower mushroom yields than materials in which the N was more readily available (poultry manure, urea, brewers' grains, hop and molasses wastes, cocoa meal). Replacement of poultry manure with the other N sources at 50–100% or wheat straw with rape, bean, or linseed straw in aerated tunnel or windrow composts reduced the OC and emissions of odorous sulfur-containing compounds, but also reduced yield. Urea and cocoa meal may be suitable for “low odor” prewetting of straw, with addition of poultry manure immediately before aerated tunnel composting. Rape straw in compost reduces the formation of anaerobic zones and resulting odorous emissions, since it maintains its structure and porosity better than wheat straw. Journal of Industrial Microbiology & Biotechnology (2002) 29, 99–110 doi:10.1038/sj.jim.7000292 Received 08 January 2002/ Accepted in revised form 20 June 2002     

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.