Co-composting of physic nut (Jatropha curcas) deoiled cake with rice straw and different animal dung

Optimizing Straw-Rotting Cultivation for Sustainable Edible Mushroom Production: Composting Spent Mushroom Substrate with Straw Additions

In recent years, the optimization of straw-rotting formulations for cultivating edible mushrooms and the management of the resulting spent mushroom substrate have emerged as new challenges. This study aimed to investigate the composting of spent mushroom substrate produced from mushroom cultivation with various straw additions, under conditions where chicken manure was also used. Parameters measured during the composting process included temperature, pH, electrical conductivity (EC), germination index (GI), moisture, and total nitrogen content. Additionally, changes in nutrient content within the compost piles before and after composting were determined, and the variations in bacterial and fungal communities across different treatments before and after composting were analyzed using 16S rRNA and ITS sequencing. The results indicated that the spent mushroom substrate produced by adding 20% straw during mushroom cultivation was more suitable for composting treatment. The findings suggest that incorporating an appropriate amount of straw in mushroom cultivation can facilitate subsequent composting of spent mushroom substrate, providing an effective strategy for both environmental protection and cost reduction.

Potassium-rich mining waste addition can shorten the composting period by increasing the abundance of thermophilic bacteria during high-temperature periods

Conventional compost sludge has a long fermentation period and is not nutrient rich. Potassium-rich mining waste was used as an additive for aerobic composting of activated sludge to make a new sludge product. The effects of different feeding ratios of potassium-rich mining waste and activated sludge on the physicochemical properties and thermophilic bacterial community structure during aerobic composting were investigated. The results showed that potassium-rich waste minerals contribute to the increase in mineral element contents; although the addition of potassium-rich waste minerals affected the peak temperature and duration of composting, the more sufficient oxygen content promoted the growth of thermophilic bacteria and thus shortened the overall composting period. Considering the requirements of composting temperature, it is recommended that the addition of potassium-rich waste minerals is less than or equal to 20%.

Straw waste promotes microbial functional diversity and lignocellulose degradation during the aerobic process of pig manure in an ectopic fermentation system via metagenomic analysis

This study compares the physicochemical properties, lignocellulose degradation, microbial community composition, and carbohydrate-active enzymes (CAZymes) in ectopic fermentation systems (EFS) of pig manure mixed with either conventional padding (C) or straw waste (A). The degradation rates of cellulose, hemicellulose, and lignin were found to be significantly higher in A (27.72%, 22.72%, and 18.80%, respectively) than in C (21.05%, 16.17%, and 11.69%, respectively) owing to the activities of lignocellulolytic enzymes. Metagenomics revealed that straw addition had a stronger effect on the bacterial community succession than fungi. The abundances of Sphingobacterium, Pseudomonas, and CAZymes were higher in A than in C, as well as the auxiliary activity enzymes, which are crucial for lignocellulose degradation. Redundancy analysis indicates a positive correlation between lignocellulose degradation and Sphingobacterium, Pseudomonas, Bacillus, and Actinobacteria contents. A structural equation model was applied to further verify that the increased microbial functional diversity was the primary driver of lignocellulosic degradation, which could be effectively regulated by the enhanced temperature with straw addition. Replacing traditional padding with straw can thus accelerate lignocellulosic degradation, promote microbial functional diversity, and improve the EFS efficiency.

Study on dynamic changes of microbial community and lignocellulose transformation mechanism during green waste composting

There are few reports on the material transformation and dominant microorganisms in the process of greening waste (GW) composting. In this study, the target microbial community succession and material transformation were studied in GW composting by using MiSeq sequencing and PICRUSt tools. The results showed that the composting process could be divided into four phases. Each phase of the composting appeared in turn and was unable to jump. In the calefactive phase, microorganisms decompose small molecular organics such as FA to accelerate the arrival of the thermophilic phase. In the thermophilic phase, thermophilic microorganisms decompose HA and lignocellulose to produce FA. While in the cooling phase, microorganisms degrade HA and FA for growth and reproduction. In the maturation phase, microorganisms synthesize humus using FA, amino acid and lignin nuclei as precursors. In the four phases of the composting, different representative genera of bacteria and fungi were detected. Streptomyces, Myceliophthora and Aspergillus, maintained high abundance in all phases of the compost. Correlation analysis indicated that bacteria, actinomycetes and fungi had synergistic effect on the degradation of lignocellulose. Therefore, it can accelerate the compost process by maintaining the thermophilic phase and adding a certain amount of FA in the maturation phase.

Addition of mature compost improves the composting of green waste

Composting is an environmentally friendly and effective way to dispose of green waste (GW), but traditional composting of GW is slow and results in the loss of many nutrients and a poor-quality compost product. In this study, mature compost (MC), which may function as an inexpensive and readily available microbial inoculant, was added to GW at 15, 20, 25, and 30% (w/w, dry weight basis) (treatments T2-T5, respectively); GW with 0.5% (v/w, dry weight basis) commercial microbial inoculum served as T1, and GW without any microbial inoculant served as the control. The treatment that produced the highest quality compost was determined based on the following compost properties: temperature, bulk density, porosity, pH, electric conductivity, contents of organic matter and nutrients, Fourier-transform infrared spectroscopy data, and phytotoxicity. The results showed that addition of 25% MC resulted in the best quality product in only 40 days.

Microbial Activity during Composting and Plant Growth Impact: A Review

Replacing harmful chemical pesticides with compost extracts is steadily gaining attention, offering an effective way for plant growth enhancement and disease management. Food waste has been a major issue globally due to its negative effects on the environment and human health. The methane and other harmful organisms released from the untreated waste have been identified as causes of this issue. Soil bacteria impart a very important role in biogeochemical cycles. The interactions between plants and bacteria in the rhizosphere are some of the factors that determine the health and fertility of the soil. Free-living soil bacteria are known to promote plant growth through colonizing the plant root. PGPR (Plant Growth Promoting Rhizobacteria) inoculants in compost are being commercialized as they help in the improvement of crop growth yield and provide safeguard and resistance to crops from disease. Our focus is to understand the mechanism of this natural, wet waste recycling process and implementation of a sustainable operative adaptation with microbial association to ameliorate the waste recycling system.

Overview on agricultural potentials of biogas slurry (BGS): applications, challenges, and solutions

The residual slurry obtained from the anaerobic digestion (AD) of biogas feed substrates such as livestock dung is known as BGS. BGS is a rich source of nutrients and bioactive compounds having an important role in establishing diverse microbial communities, accelerating nutrient use efficiency, and promoting overall soil and plant health management. However, challenges such as lower C/N transformation rates, ammonia volatilization, high pH, and bulkiness limit their extensive applications. Here we review the strategies of BGS valorization through microbial and organomineral amendments. Such cohesive approaches can serve dual purposes viz. green organic inputs for sustainable agriculture practices and value addition of biomass waste. The literature survey has been conducted to identify the knowledge gaps and critically analyze the latest technological interventions to upgrade the BGS for potential applications in agriculture fields. The major points are as follows: (1) Bio/nanotechnology-inspired approaches could serve as a constructive platform for integrating BGS with other organic materials to exploit microbial diversity dynamics through multi-substrate interactions. (2) Advancements in next-generation sequencing (NGS) pave an ideal pathway to study the complex microflora and translate the potential information into bioprospecting of BGS to ameliorate existing bio-fertilizer formulations. (3) Nanoparticles (NPs) have the potential to establish a link between syntrophic bacteria and methanogens through direct interspecies electron transfer and thereby contribute towards improved efficiency of AD. (4) Developments in techniques of nutrient recovery from the BGS facilities' negative GHGs emissions and energy-efficient models for nitrogen removal. (5) Possibilities of formulating low-cost substrates for mass-multiplication of beneficial microbes, bioprospecting of such microbes to produce bioactive compounds of anti-phytopathogenic activities, and developing BGS-inspired biofertilizer formulations integrating NPs, microbial inoculants, and deoiled seed cakes have been examined.

Efficiency and mechanism of a vermicompost additive in enhancing composting of swine manure

Vermicompost was used as an additive in swine manure composting to investigate the expression of bacterial functional genes on nutrients biotransformation. Three treatments with vermicompost compositions of 10%, 20%, and 30% in swine manure were set up. Raw manure was used as the control. The thermophilic period increased to 12 days, the NH₄⁺ -N/NO₃^- -N ratio decreased to 0.85, and the germination index (GI) increased to 166% after vermicompost addition. Furthermore, higher relative abundances of Firmicutes were observed in the substrate during the initial stages of experiment. The abundance of the dominant phylum Proteobacteria and its related pathogenic genera Acinetobacter and Stenotrophomonas decreased in the thermophilic stage while the potentially beneficial genera Actinomadura and Chryseolinea increased. The expression of primary functional genes associated with the metabolism of carbohydrates, amino acids, xenobiotics, and fatty acids was enhanced during the thermophilic phase. Besides, most dominant genera showed strengthened correlations with NO₃^--N and GI, which were the strongest environmental factors for bacterial communities. Network analysis revealed a new metabolic pathway associated with dominant genera Pseudomonas, Acinetobacter, Stenotrophomonas, and Oceanobacter, whose abundance increased with vermicompost addition. Collectively, the results of this study indicate that vermicompost can promote composting efficiency by increasing the potentially beneficial bacteria, decreasing pathogenic bacteria, and enhancing the metabolic capacity of bacterial communities.

Planifilum fulgidum Is the Dominant Functional Microorganism in Compost Containing Spent Mushroom Substrate

The extensive accumulation of spent mushroom substrate (SMS) owing to the large-scale production of edible fungi is causing environmental problems that cannot be ignored. Co-composting is a promising method for agricultural and animal husbandry waste disposal. In this study, the composition and function of microbial communities in the process of cattle manure–maize straw composting with SMS addition were compared through an integrated meta-omics approach. The results showed that irrespective of SMS addition, the predominant fungi were Ascomycota, while the dominant bacteria were Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes. High temperature promoted the evolution from Gram-negative bacteria (Bacteroides, Proteobacteria) to Gram-positive bacteria (Firmicutes, Actinomycetes). The composting process was accelerated by SMS addition, and the substrate was effectively degraded in 14 days. Metaproteomics results showed that the dominant microorganism, Planifilum fulgidum, secreted large amounts of S8, M17, and M32 proteases that could degrade macromolecular protein substrates in the presence of SMS. Planifilum fulgidum, along with Thermobifida fusca and Melanocarpus albomyces, synergistically degraded hemicellulose, cellulose, and protein. In addition, the dominant microorganisms related to the initial raw materials such as Pichia, Lactobacillus in the microbial agent and Hypsizygus in SMS could not adapt to the high-temperature environment (>60 °C) and were replaced by thermophilic bacteria after 5 days of composting.

Testing the plastic-wrapped composting system to dispose of swine mortalities during an animal disease outbreak

Composting has been used to dispose of animal mortalities and infected materials, such as manure and feed, during major animal disease outbreaks. In this study, we adapted the plastic-wrapped mortality composting system developed by the Canadian Food Inspection Agency during the 2004 highly pathogenic avian influenza outbreak to compost swine mortalities. The goals of the study were to evaluate the performance of the plastic-wrapped composting system to dispose of swine mortalities and to field test its ability to eliminate the spread of airborne pathogens through the aeration ducts. Two cover materials, ground cornstalks and woodchips, were tested using passively and actively aerated composting sheds. The mortalities were inoculated with Salmonella spp. and vaccine strains of Bovine herpesvirus-1 and Bovine viral diarrhea virus. Air samples collected from the upper aeration duct (air outlet) during the first 10 d of composting were negative for Salmonella and the viruses tested, which indicated that aerosol transmission of the pathogens was limited. The aeration plenum placed under the mortalities helped to keep conditions aerobic, as O₂ concentrations of both passively and actively aerated test units were above 11%. Actively aerated cornstalks had the highest degree-hours (1,462 °C h d^-1 ), which was followed by passively aerated cornstalks (1,312 °C h d^-1 ), actively aerated woodchips (1,303 °C h d^-1 ), and passively aerated woodchips (1,062 °C h d^-1 ). After a 7-wk composting period, all three pathogens were inactivated based on quantitative polymerase chain reaction test results. The mortalities were not inoculated with the African swine fever virus, but temperature data showed that if they were, the system had the potential to eliminate this virus.

Bridging GNSS Outages with IMU and Odometry: A Case Study for Agricultural Vehicles

Nowadays, many precision farming applications rely on the use of GNSS-RTK. However, when it comes to autonomous agricultural vehicles, GNSS cannot be used as a stand-alone system for positioning. To ensure high availability and robustness of the positioning solution, GNSS-RTK must be fused with additional sensors. This paper presents a novel sensor fusion algorithm tailored to tracked agricultural vehicles. GNSS-RTK, an IMU and wheel speed sensors are fused in an error-state Kalman filter to estimate position and attitude of the vehicle. An odometry model for tracked vehicles is introduced which is used to propagate the filter state. By using both IMU and wheel speed sensors, specific motion characteristics of tracked vehicles such as slippage can be included in the dynamic model. The presented sensor fusion algorithm is tested at a composting site using a tracked compost turner. The sensor measurements are recorded using the Robot Operating System (ROS). To analyze the achievable accuracies for position and attitude of the vehicle, a precise reference trajectory is measured using two robotic total stations. The resulting trajectory of the error-state filter is then compared to the reference trajectory. To analyze how well the proposed error-state filter is suited to bridge GNSS outages, GNSS outages of 30 s are simulated in post-processing. During these outages, the vehicle's state is propagated using the wheel speed sensors, IMU, and the dynamic model for tracked vehicles. The results show that after 30 s of GNSS outage, the estimated horizontal position of the vehicle still has a sub-decimetre accuracy.

Improving sewage sludge compost process and quality by carbon sources addition

In present study, the effects of carbon sources on compost process and quality were evaluated in the lab-scale sewage sludge (SS) composting. The composting experiments were performed for 32 days in 5 L reactors. The results showed that carbon sources could change the nitrogen conversion and improve the compost quality. Especially, the readily degradable carbon source could promote organic matter degradation, improve nitrogen conversion process and accelerate compost maturation. The addition of glucose and sucrose could increase dissolved organic carbon, CO₂ emission, dehydrogenase activity, nitrification and germination index during the SS composting. That's because glucose and sucrose could be quickly used by microbes as energy and carbon source substance to increase activity of microbes and ammonia assimilation. What's more, the NH₃ emission was reduced by 26.9% and 32.1% in glucose and sucrose treatments, respectively. Therefore, the addition of readily degradable carbon source could reduce NH₃ emission and improve compost maturity in the SS composting.

Improvement of two-stage composting of green waste by addition of eggshell waste and rice husks

With the development of urban greening and increases in the human population, the production of green waste (GW) has been increasing in China. Although GW is biodegradable, its composting is difficult because of its low degradation rate. This study focuses on how addition of eggshell waste (ESW; at 0, 10, and 20%) and/or rice husks (RH; at 0, 15, and 25%) affects the two-stage composting of GW on the basis of temperature, bulk density, particle-size distribution, pH, nitrogen changes, carbon dioxide emission, organic matter degradation, humic substances, the activities of microorganisms and enzymes, and the phytotoxicity to germinating seeds. The combined addition of 10% ESW and 25% RH produced the highest quality compost in the shortest time. To produce a stable and mature product, two-stage composting of GW required 30 days without additives but only 20 days with the combined addition of 10% ESW and 25% RH.

Gasification filter cake reduces the emissions of ammonia and enriches the concentration of phosphorous in Caragana microphylla residue compost

Nutrient loss is a major problem during agricultural waste composting. This study investigated the impact of gasification filter cake (GFC) addition on gaseous emissions and nutrient loss during composting of chicken manure mixed with Caraganna microphylla straw. The GFC was added to the composting mix at dry weight rates of 0% (GFC₀), 6.25% (GFC_6.25), 12.5% (GFC_12.5), 25% (GFC₂₅) and 50% (GFC₅₀). Overall, GFC_12.5 and GFC₂₅ efficiently enhanced organic matter decomposition, reduced N loss and enriched P and K concentrations during composting, as compared to GFC₀. However, GFC_6.25 did not show a significant effect on organic matter decomposition, while GF_C50 had no effect on N loss. As a result, an overall enhancement of nutrient contents was observed in the final composts of GFC_12.5 and GFC₂₅. These results suggest that the addition of GFC at moderate-rates (i.e. 12.5% and 25%) can enhance nutrient retention and thereby result in a nutrient-rich compost.

Composting of toxic weed Parthenium hysterophorus: Nutrient changes, the fate of faecal coliforms, and biopesticide property assessment

This study aimed to investigate; composting of toxic weed Parthenium with cow dung in (2:1, and 1:1 ratio); and the changes in Escherichia coli and Salmonella population; as well as the antimicrobial property of ready compost. Organic carbon decreased by 45-52% while total nitrogen, total potassium, available phosphorus increased by 1.87- to 3.21-, 1.65- to 1.83-, and 4.03- to 3.33-folds, respectively in Parthenium setups. Germination index value (110-132%) indicates no phytotoxicity of composted Parthenium. E. coli reduced by 6.87 to 6.90 log population (<1000 CFU g^-1, safe limit) while Salmonella was in non-detectable limit in compost samples. Results of the antimicrobial test indicate a strong biocidal activity by non-sterilized compost extract against plant pathogens Xanthomonas citrus, Xanthomonas campestris, and Erwinia carotovora. Xanthomonas spp. It is concluded that thermophilic composting could convert Parthenium into a product with biomanure and biopesticide property for sustainable agriculture production.

Comparing the agrochemical properties of compost and vermicomposts produced from municipal sewage sludge digestate

The aim of this work was to investigate whether the agronomic traits of vermicompost prepared from partially stabilised sewage sludge digestate after thermophilic composting were more favourable than those of conventional compost. The effects of various additives (green waste, spent mushroom compost, wheat straw, biochar) were also tested after 1.5 months precomposting followed by 3 months vermicomposting with Eisenia fetida or by compost maturing. Vermicomposting did not result in significantly more intensive mineralisation than composting; the average organic carbon contents were 21.2 and 22.2% in vermicomposts and composts, respectively. Hence, the average total (N: 2.4%; P: 1.9%; K: 0.9%) and available (N: 160 mg/kg; P: 161 mg/kg; K: 0.8%) macronutrient concentrations were the same in both treatments. The processing method did not influence the organic matter quality (E₄/E₆) either. However, on average the concentration of the plant growth regulator kinetin was more than twice as high in vermicomposts.

Insights into functional microbial succession during nitrogen transformation in an ectopic fermentation system

The ectopic fermentation system (EFS) is an advanced technology for treating farm wastewater, and it reduces ammonia nitrogen emission and nitrogen loss of fermentation products. This study observed the functional bacteria succession related to nitrogen metabolism in EFS by high throughput sequencing, and evaluated their associations with environmental factors. Results revealed that with the changes of temperature, pH, moisture content, and nitrogen content during fermentation, the species richness and diversity of ammonia oxidizing bacteria (AOB) with amoA increased, but those of denitrifying bacteria carrying nirK and nosZ decreased. During the fermentation process, the dominant bacterial populations of AOB and denitrifying bacteria changed significantly, and different bacterial populations showed different positive/negative correlations with the environmental factors. This study revealed the role of functional bacteria in ammonia removal and nitrogen conservation of EFS, and provided a theoretical basis for the improvement of microbial agents and EFS application.

Effect of initial material bulk density and easily-degraded organic matter content on temperature changes during composting of cucumber stalk

To inactivate the potentially pathogenic microorganisms and safely utilize vegetable waste compost, ultra-high temperatures (>70°C) should be maintained during the composting without having an inhibitory effect on maturity. This study investigated the influence of bulk density (part 1) and easily-degraded organic matter content (EDOMC, part 2) on temperature evolution during vegetable waste composting: Part 1: corn straw with different particle sizes was used to achieve different bulk densities in the composting material (BD1-BD3); Part 2: partial or total substitution of the corn straw by corn starch was carried out to obtain different EDOMC (ED1-ED4). The composting experiments were conducted in a lab-scale reactor (1.75kg material) and lasted for 30d. Temperature and CO₂ emission were recorded daily, and the organic matter, lignocellulose, microbial activity, germination index (GI) and C/N of the samples were measured at different stages. The highest temperature (65.7°C) in part 1 occurred in the treatment with the bulk density of 0.35g/cm³, which also had the longest thermophilic phase. Bulk density was found to seriously influence the utilization efficiency of O₂ and heat transfer through materials, rather than heat production from organic matter degradation. In experiment part 2, the highest temperature was obtained with EDOMC of 45% (71.4°C). Therefore, adjusting the bulk density to 0.35g/cm³ and the easily-degraded organic matter content of the initial material to 45% was the best combination for reaching temperatures above 70°C during composting, with no inhibitory effect on the maturity of the compost product.

A comparative study of pig manure with different waste straws in an ectopic fermentation system with thermophilic bacteria during the aerobic process: Performance and microbial community dynamics

In the present study, ectopic fermentation systems were treated with both solid and liquid waste from livestock. Then, the various physicochemical properties and compositions of microbial communities in different waste straws treatments were compared. The addition of thermophilic bacteria was beneficial to the decomposition of litter, and it improved the fermentation process. Proteobacteria, Bacteroidetes, and Firmicutes were the predominant types in the fermentation vessels, and the presence of the phyla Proteobacteria and Bacteroidetes was correlated with factors prevailing in the mature phase. Furthermore, pig manure with sawdust, rape stem, and rice chaff and pig manure with sawdust, rice straw, and rice chaff vessels had higher concentrations of dissolved nitrogen, which were conducive to the conversion of fermentation wastes into useful fertilizer. These results demonstrate the feasibility of using rape stem and rice straw as padding materials during the treatment of both liquid and solid livestock waste in ectopic fermentation systems.

Rapid composting techniques in Indian context and utilization of black soldier fly for enhanced decomposition of biodegradable wastes - A comprehensive review

In the present scenario, solid waste management (SWM) has become one of the main concerns for urban waste managers in the developing world. This article reviews the recent trends and technologies associated with the process of composting. Utilization of black soldier fly (BSF) larvae can be one of the rapid methods for treatment of biodegradable wastes. A detailed review of the literature indicated that more importance is to be given on the pre-processing of Municipal Solid Waste (MSW) which includes segregation of biodegradables, inerts, metals for preparing the requisite substrate for application of the suitable technology. In developing countries, major emphasis should be given on curtailing the environmental and health impacts caused due to improper management of MSW and for developing some innovative as well as economically feasible systems for proper handling of MSW. BSF can transform the biodegradable wastes into biofuels and byproducts at a minimal cost. The utilization of BSF for treating various organic waste (OW) has been thoroughly studied and discussed in detail. The salient observations on the factors affecting the growth of BSF larvae as well as comprehensive analysis of patents on breeding and utilization of BSF are also presented in this paper. The present review also assesses the potential of various rapid composting techniques and advocates about the planning and development of real-scale treatment systems by the researchers, environmental planners and policy makers to eradicate the problem of solid wastes.

Evaluation of total greenhouse gas emissions during sewage sludge composting by the different dicyandiamide added forms: Mixing, surface broadcasting, and their combination

The aim of this work was to compare the impact of different adding forms of dicyandiamide (DCD) on NH₃ and greenhouse gas (GHG) emissions during sewage sludge (SS) composting. Four treatments were set up using SS mixed with sawdust, to which DCD was then added by mixing (M), surface broadcasting (B), and a combination of the two (M+B). The treatment without DCD applied was used as the control. The results indicate that the addition of DCD slightly inhibited the organic matter (OM) degradation, but that it had no significant effect on CO₂ emission. The surface mulching of DCD has no significant effect on NH₃, N₂O, and CH₄ emissions. The mixing addition of DCD significantly increased the NH₃ emission by 32.5% compared to that of the control. The N₂O emission for the M and M+B treatments significantly decreased by 35.1% and 51.8%, respectively. The CH₄ emission for the M and M+B treatments decreased by 33.9% and 31.8%, respectively. In addition, the total GHG emissions for the M and M+B treatments were significantly reduced by 16.7-25.7% (P < 0.05) compared to those of the control. Therefore, to reduce the total GHG emissions of the SS composting process, the addition of DCD by a combination of mixing and surface mulching is strongly recommended as a highly efficient solution.

Improving sewage sludge composting by addition of spent mushroom substrate and sucrose

The effects of spent mushroom substrate (SMS) and sucrose (S) amendment on emissions of nitrogenous gas (mainly NH₃ and N₂O) and end products quality of sewage sludge (SS) composting were evaluated. Five treatments were composted for 20 days in laboratory-scale using SS with different dosages of SMS and S, without additive amended treatment used as control. The results indicated that SMS amendments especially combination with S promoted dehydrogenase activity, CO₂ production, organic matter degradation and humification in the composting, and maturity indices of composting also showed that the 30%SMS+2%S treatment could be much more appropriate to improve the composting process, such as total Kjeldahl nitrogen, nitrification index, humic acids/fulvic acids ratio and germination index, while the emissions of NH₃ and N₂O were reduced by 34.1% and 86.2%, respectively. These results shown that the moderate addition of SMS and S could improve the compost maturity and reduce nitrogenous gas emission.

Resource recovery of food waste through continuous thermophilic in-vessel composting

In the Kingdom of Saudi Arabia (KSA) and Gulf region, a very small amount of municipal solid waste (MSW) is treated for compost production. The produced compost through traditional methods of compost piles and trenches does not coincide with the international standards of compost quality. Therefore, in this study, a continuous thermophilic composting (CTC) method is introduced as a novel and efficient technique for treating food waste into a quality compost in a short period of time. The quality of the compost was examined by degradation rates of organic matter (OM), changes in total carbon (TC), ash contents, pH, dynamics in ammonium nitrogen (NH₄-N) and nitrate nitrogen (NO₃-N), and nitrification index (NI). The results showed that thermophilic treatment at 60 °C increased the pH of the substrate and promoted degradation and mineralization process. After 30 days of composting, the degree of OM degradation was increased by 43.26 and 19.66%, NH₄-N by 65.22 and 25.23%, and NO₃-N by 44.76 and 40.05% as compared to runs treated at 25 and 40 °C, respectively. The stability of the compost was attained after 30 to 45 days with quality better than the compost that was stabilized after 60 days of the experiment under mesophilic treatment (25 °C). The final compost also showed stability at room temperature, confirming the rapid degradation and maturation of food waste after thermophilic treatment. Moreover, the quality of produced compost is in line with the compost quality standard of United States (US), California, Germany, and Austria. Hence, CTC can be implemented as a novel method for rapid decomposition of food waste into a stable organic fertilizer in the given hot climatic conditions of KSA and other Gulf countries with a total net saving of around US $70.72 million per year.

Composting technology in waste stabilization: On the methods, challenges and future prospects

Composting technology has become invaluable in stabilization of municipal waste due to its environmental compatibility. In this review, different types of composting methods reportedly applied in waste management were explored. Further to that, the major factors such as temperature, pH, C/N ratio, moisture, particle size that have been considered relevant in the monitoring of the composting process were elucidated. Relevant strategies to improve and optimize process effectiveness were also addressed. However, during composting, some challenges such as leachate generation, gas emission and lack of uniformity in assessing maturity indices are imminent. Here in, these challenges were properly addressed and some strategies towards ameliorating them were proffered. Finally, we highlighted some recent technologies that could improve composting.

Effect of turning frequency on co-composting pig manure and fungus residue

Composting of agricultural wastes not only can reduce environmental pollution caused by improper disposal, but also can recycle agricultural wastes and transform them into highly valuable products, such as fertilizers or soil conditioners, for agricultural applications. However, the composting process and final product are easily affected by the limited oxygen supply that results from insufficient aeration, especially in the center of a large-scale windrow. Hence, a pilot-scale experiment was conducted to investigate the effects of the turning frequency on the composting efficiency and compost quality of used pig manure and fungus residue. Physical and chemical characteristics were measured over the course of 63 days of composting. The data indicate that higher temperatures and more rapid moisture removal generally result from a turning treatment of once every 2-4 days than in fewer, or no, turning treatments. The total nitrogen, total phosphorus, and total potassium contents increased in all windrows as the organic matter content decreased, but both the increases and decrease were greater in windrows that were turned more frequently. The reduction of the organic matter mass by 53.7-66.0% for a turning of once every 2-8 days is significantly higher than that for the static windrow (39.1%). Although there is an increase in nitrogen mass loss with an increased turning frequency, lower nitrogen mass losses (12.7-25.7%) in all treatments were noted compared with previous studies. A final compost product with less moisture, less weight, higher nutrient content (N, P, and K), and greater stability was obtained in windrows with turning frequencies of once every 2-4 days, which is recommended when composting pig manure and fungus residue.

IMPLICATIONS

Composting of agricultural wastes not only can reduce environmental pollution caused by improper disposal, but recycling of agricultural wastes transforms them into highly valuable products, such as fertilizers or soil conditioners, for agricultural applications. However, the composting process and final product are easily affected by the limited oxygen supply that results from insufficient aeration, especially in the center of a large-scale windrow. Hence, a pilot-scale experiment was conducted to investigate the effects of the turning frequency on the composting efficiency and compost quality of used pig manure and fungus residue, so as to capture an operational technique suitable for the effective co-composting pig manure and edible fungi residue for a large-scale composting plant.

Feasibility of co-composting of sewage sludge, spent mushroom substrate and wheat straw

In this study, the lab-scale co-composting of sewage sludge (SS) with mushroom substrate (SMS) and wheat straw (WS) conducted for 20days was evaluated. The addition of SMS evidently increased CO₂ production and dehydrogenase activity. The combined addition of SMS and WS significantly improved the compost quality in terms of temperature, organic matter degradation and germination index, especially, reduced 21.9% of NH₃ emission. That's because SMS and WS possessed the complementarity of free air space and contained plenty of degradable carbon source. The SMS could create a comfortable environment for the nitrifying bacteria and improve nitrification. The carbohydrates from combined addition of SMS and WS could be utilized by thermophilic microorganisms, stimulate ammonia assimilation and reduce NH₃ emission. These results suggested that adding SMS and WS could not only improve the degradation of organic matter and the quality of compost product, but also stimulate ammonia assimilation and reduce ammonia emission.

Straw biochar hastens organic matter degradation and produces nutrient-rich compost

Biochar derived from wheat straw was added to pig manure in amounts equivalent to 5%, 10%, or 15% (w/w, wet weight). The ratios of NH4(+)/NO3(-) and of UV light absorption at a wavelength of 254nm (SUV254) and dissolved organic carbon (DOC) indicated that compost with 10-15% biochar became more mature and more humified within 42days of composting, and the content of DOC and the concentration of NH4(+) in such compost decreased by 37.5-62.0% and 4.0-20.9%, respectively, compared to the corresponding levels in the control. Addition of biochar lowered the pH and increased electrical conductivity by 7.0-37.5% compared to the control and also increased the concentrations of water-soluble nutrients including PO4(3-) (5.6-7.4%), K(+) (14.2-58.6%), and Ca(2+) (0-12.5%). It is therefore recommended that straw biochar be added to pig manure at 10-15% by weight.

Improved fermentation performance in an expanded ectopic fermentation system inoculated with thermophilic bacteria

Previous research showed that ectopic fermentation system (EFS) inoculated with thermophilic bacteria is an excellent alternative for cow wastewater treatment. In this study, the effects of thermophilic bacterial consortium on the efficiency and quality of the fermentation process in EFS were evaluated by measuring physicochemical and environmental factors and the changes in organic matter composition. In parallel, the microbial communities correlated with fermentation performance were identified. Inoculation of EFS with thermophilic bacterial consortium led to higher temperatures, increased wastewater requirements for continuous fermentation, and improved quality of the litters in terms of physicochemical factors, security test, functional group analysis, and bacterial community composition. The relationship between the transformation of organic component and the dominant bacteria species indicated that environmental factors contributed to strain growth, which subsequently promoted the fermentation process. The results highlight the great potential of EFS model for wide application in cow wastewater treatment and re-utilization as bio-fertilizer.

The potential of using low cost naturally available biogenic substrates for biological removal of chlorophenol

This study details the application of naturally available biogenic substrates (NABS) in microbial degradation of 2-chlorophenol (CP). Jatropha deoiled cakes (JDC) and Karanja deoiled cakes (KDC) are used as NABS. The potential of NABS is compared with standard biogenic substrate, glucose. The study was carried out with both acclimatized mixed culture and pure culture, Pseudomonas putida. Microbial activity of the culture was monitored by measuring reduction in chlorophenol concentration, COD, toxicity and Cl(-) ions evolution. The study was carried out for a total of 42days. It was observed that culture having NABS has shown similar chlorophenol reduction but higher COD and toxicity reduction. Amongst NABS, Jatropha deoiled cake (JDC) has shown superior results of 71% COD reduction compared to glucose and KDC. This study is one of the first kind illustrating the potential of these substrates in removing toxic chemicals from wastewaters.

Changes in physical, chemical, and microbiological properties during the two-stage co-composting of green waste with spent mushroom compost and biochar

This research determined whether the two-stage co-composting can be used to convert green waste (GW) into a useful compost. The GW was co-composted with spent mushroom compost (SMC) (at 0%, 35%, and 55%) and biochar (BC) (at 0%, 20%, and 30%). The combined addition of SMC and BC greatly increased the nutrient contents of the compost product and also improved the compost quality in terms of composting temperature, particle-size distribution, free air space, cation exchange capacity, nitrogen transformation, organic matter degradation, humification, element contents, abundance of aerobic heterotrophs, dehydrogenase activity, and toxicity to germinating seeds. The addition of 35% SMC and 20% BC to GW (dry weight % of initial GW) and the two-stage co-composting technology resulted in the production of the highest quality compost product in only 24 days rather than the 90-270 days required with traditional composting.

Method of phorbol ester degradation in Jatropha curcas L. seed cake using rice bran lipase

A novel enzymatic degradation of phorbol esters (PE) in the jatropha seed cake was developed using lipase. Cihera rice bran lipase had the highest ability to hydrolyze PE, and reduced PE to a safe level after 8 h of incubation. Enzymatic degradation may be a promising method for PE degradation.

Pretreatment and hydrolysis methods for recovery of fermentable sugars from de-oiled Jatropha waste

The release of reducing sugars (RS) upon various pretreatments and hydrolysis methods from de-oiled Jatropha waste (DJW) was studied. The highest RS concentration of 12.9 g/L was observed at 10% enzyme hydrolysis. The next highest RS of 8.0 g/L and 7.8 g/L were obtained with 10% HCl and 2.5% H2SO4, respectively. The NaOH (2.5%), ultrasonication and heat (90°C for 60 min) treatments showed the RS concentration of 2.5 g/L, 1.1 g/L and 2.0 g/L, respectively. Autoclave treatment slightly enhanced the sugar release (0.9 g/L) compared to no treatment (0.7 g/L). Glucose release (11.4 g/L) peaked in enzyme hydrolysis. Enzyme treated acid unhydrolysed biomass showed 11.1 g/L RS. HCl and H2SO4 pretreatment gave maximal xylose (6.89 g/L and 6.16 g/L, respectively). Combined (acid and enzyme) hydrolysis employed was efficient and its subsequent batch hydrogen fermentation showed a production 3.1 L H2/L reactor.

Evolution of process parameters and determination of kinetics for co-composting of organic fraction of municipal solid waste with poultry manure

This study aimed to monitor the process parameters and to determine kinetics in composting of organic fraction of municipal solid waste (OFMSW) and poultry manure. The experiments were carried out with three different mixtures. The results showed that the mixture 60% OFMSW, 20% poultry manure, 10% mature compost and 10% sawdust provided the most appropriate conditions for composting process. Using nine kinetic models and nonlinear regression method, kinetic parameters were estimated and the models were analyzed with four statistical indicators. Kinetic models with four measured variables proved to be better than models with less number of measured variables. The number of measured experimental variables influences kinetics more than the number of kinetic parameters. Satisfactory fittings of proposed kinetic model to the experimental data of OM were achieved. The model is more suitable for data obtained from composting of mixtures with much higher percentage of OFMSW than percentage of poultry manure.

Bioaugmented composting of Jatropha de-oiled cake and vegetable waste under aerobic and partial anaerobic conditions

This study was conducted to assess the effect of microbial inoculation in Jatropha cake composting with different vegetable waste. The microbial inoculums composed of fungal strains (Aspergillus awamori, Aspergillus nidulans, Trichoderma viride, Phanerochaete chrysosporium) and bacterial inoculums (Pseudomonas striata as phosphorus solublizer and Azotobacter chroococcum as nitrogen fixer) were added to the compost mixture after the thermophilic phase was over for bioaugmenting of Jatropha cake under aerobic and partial anaerobic conditions. Addition of both fungal and bacterial inoculum with mixed substrate (Jatropha cake + vegetable waste) during composting (aerobic and partial anaerobic) showed, better results as compared to compost with only fungal inoculants. Increased enzymatic activity initially, during composting (like dehydrogenase, alkaline phosphatase activity and FDA) proved role of inoculated microbes in rapid decomposition. Analysis of compost (with both bacterial and fungal inoculum) showed presence of high humus (12.7%), humic acid (0.5%), fulvic acid (5.68%), soluble protein content and low C/N ratio. Decreased in concentration of extractable metals (Cu, Fe and Mn) were recorded at maturity in all the substrate composts. The C/N ratio was significantly correlated to parameters like humic acid, humus, fulvic acid, protein and also microbial activity parameters. We conclude that the composting of de-oiled Jatropha cake with different vegetables waste could be feasible and sustainable approach in recycling of agricultural and industrial residues in huge quantities.