Purpose Agro-industrial wastes are posing serious challenges for the agro-industries. Composting and co-composting of such wastes will lead to converting such wastes into a useful product that will serve as a soil conditioner. The present research investigated the kinetics of composting and co-composting of several agro-industrial wastes.Methods Seven pilot scale composting and co-composting piles of substrates from grain dust (GD), coffee-processing waste (CPW) and olive mill waste (OMW) were tested. Temperature and moisture content of the piles were monitored during the composting process and adjusted whenever necessary.Results The biodegradation kinetics was found to be of first order for all composting and co-composting piles. As judged by the value of the reaction rate constant, and the temperature of the piles, the biodegradability of the grain dust was the highest among all composting piles, followed by the coffee-processing residue and finally the fresh olive mill waste. As for the co-composting, the highest degradability was noticed in the pile that was composed of grain dust and coffee-processing waste followed by that of grain dust mixed with dry olive mill waste, and then followed by coffee-processing waste and dry olive mill waste and finally by grain dust with fresh olive-processing waste.Conclusions Composting and co-composting of agro-industrial wastes is a low cost and an environmentally friendly waste management option for solving the problem of the disposal of such waste. The study revealed that all piles followed first-order kinetics with different biodegradability rates.

There is a widespread interest in converting organic waste into compost fertilizer to extend the life of landfills, create economic and environmental benefits, and ultimately reduce the pressure on local governments in managing the ever-increasing complexity of municipal solid waste. However, composting is still seldom considered as a strategic element. There is also very little evidence available of its economic feasibility. This study, therefore, aims to analyze key factors that influence the economic feasibility of municipal composting plant and identify a range of plant capacity or scale where a composting project could have higher opportunity to be financially sustainable. A cost–benefit analysis (CBA) was carried out using the data gathered from five composting plants in Asia, including Surabaya, Bali and Bekasi in Indonesia, Beijing in China, and Matale in Sri Lanka. The results identified that the medium-scale and lower largescale composting plants have an optimal opportunity for being financially feasible as compared with the smaller and larger capacity plants. The study also identified that the economic viability of the composting plants depends on the number of factors, such as selection of suitable processing methods, technologies, scale, quality of product and marketing strategies. The advantages of the medium and lower large-scale composting plants are (1) waste input and product quality are easier to control than larger scale compost plants, and (2) there are extra income opportunities such as tipping fees and carbon credits that are limited in the case of small-scale composting plants. The scale of composting plant is one of the key factors to be considered at the initial stage of planning composting plants.

Background Organic: solid waste management is a major challenge in high population density areas like apartments, educational institutions, hospitals, etc., as their disposal with other wastes could not only lead to issues like vector menace, odour generation but also would lead to loss of resources that could be reused such as nutrients which will benefit soil. In places like educational institutions, the major portion of waste generated is organic waste, especially food waste and yard waste from the campus, apart from paper waste. Composting is an organic waste treatment method that is cost effective and leads to resource recovery. In this study, the characteristics of composting of yard waste and co-composting of yard waste with wastes generated in an institution (university campuses of Anna University, Chennai, India) are examined. The composts were characterized in terms of total solids, volatile solids, pH, electrical conductivity, carbon: nitrogen (C: N) ratio and total Kjeldahl nitrogen. The stability index and germination index of the compost were assessed.Results: The C: N ratio of all the different composts (except the one generated from yard with canteen waste consisting of vegetable waste) produced in this study has a value less than 30: 1, which satisfies the basic requirements for the compost. It was also observed that the mature compost from these feedstocks did not have heavy metals at toxic levels.Conclusion: This study demonstrated that the co-composting of yard wastes with paper and canteen wastes (fruit, coffee grounds, tea leaf waste) could produce value-added products. In addition to that, kinetic models were developed to predict the decomposition rate constant of the process.

Effectiveness of the separate collection system is the most important thing in the production of highquality compost. The present work aims to analyzed the mass balance of two separating machine components used in Babol composting facility (with capacity of 100 ton/day and 250 ton/day) based on recovery factor transfer function (RFTF) model to evaluate their efficiency. After sampling from the input and output of the processing line machines and quantitative and qualitative analysis of the waste, material balance was modeled based on RFTF. Calculations were performed for compost processing lines and a standard material balance diagram was prepared for both separation systems. Results showed that the new processing line of the Babol composting facility (with a capacity of 250 ton/day) has a more favorable performance compared to the old processing line (with a capacity of 100 ton/day). The new line reduced the amount of rejecting waste (refuse compost) by 19. 84% compared to the old processing line. Also, by using this processing line, the amount of separated organic waste which will be later used in the fermentation and aeration phase of compost production was increased by 19. 39%. In addition, the ratio of extracted materials with economic value was increased by 0. 45%. Expanded Abstract Introduction The municipal solid waste composting line consists of three main phases: 1) separation, 2) aeration, and 3) final processing. The main purpose of the separation phase is isolating the compostable materials, i. e., organic materials, and reducing their size. Having high efficiency separating equipment is necessary for producing high quality compost. In this study, the mass balance of separating equipment used in Babol compost production plant was analyzed in order to evaluate its efficiency. Furthermore, the comparison of the acquired mass balance to the standard recovery factor transfer function (RFTF) model was conducted and corrective strategies to improve the efficiency of separating equipment was proposed. Materials and methods The Babol compost production plant was set up in 2000 with the initial capacity of 100 tons of mixed municipal waste per day. The production line consisted of an 8-meter trommel screen without magnet, a bag opener, and other mechanical separators. In 2018, the production line was renovated with the increased capacity of 250 tons per day to meet the new demands. More specifically, the new production line employs: 1) two 8-meter and 12-meter trommel screens, 2) one bag opener, 3) two magnets, 4) and a PLC control system. Mass balance analysis, which is the direct application of law of conservation of mass, is the key to evaluating efficiency of processing systems. The results of such an analysis can be used to determine the proper capacity of separating units. RFTF can be shown by a diagonal matrix, where each diagonal element represents the percentage of a specific component in the waste stream after the processing. These components include ferrous metals, non-ferrous metals, glass, paper, plastics, residual organic materials (OR), and residual inorganic materials (IR). In this study, to carry out our analysis, we compare the output of RFTF model with the mass balance of old and new (250 tons per day) processing lines. The physical analysis of input waste flow of RFTF is provided by the municipality of Babol. We took samples from input and output of processing line at multiple times for classification of component into the seven aforementioned groups. Discussion of Results Based on our physical analysis and the RFTF model calculations, the separation ratio of materials in the rotating circle of the old processing line with capacity of 100 tons of waste per day (12. 5 tons per hour) is 52. 78% under the sieve and 47. 22% on sieve. Moreover, the 12-meter trommel screen of the processing line with capacity of 250 tons of waste per day (31. 2 tons per hour) separates materials with the separation ratio of 50. 82% on sieve and 49. 18% under the sieve. These values for the 8-meter trommel screen with the input capacity of 15. 87 tons of waste per hour are 52. 96% on sieve and 47. 04% under the sieve. The separation ratios of materials in the waste processing unit of the old production line were 52. 8% organic matter (i. e., composting capacity), 44. 8% final residue (burial waste), and 2. 4% of the material with economic value (extracted in the manual recycling stations). In comparison with the output of the RFTF model with the same input material ratio, separates 9. 6% less organic materials which were buried in the landfill. Also, the separation ratios of the material in the waste processing unit of the new production line are 72. 19% organic matter (composting capacity), 24. 96% final disposal (burial waste) and 2. 85% materials of economic value (extracted in the manual recycling stations and by magnets). The new line separate 0. 19% less organic matter, and 7. 17% less materials with economic value compared with the output of RFTF model with the same input material ratio. Consequently, the percentage of final materials to be shipped to landfill for burial is 7. 36% higher. Conclusions Our findings show that the new processing line of the composting plant of Babol (with a capacity of 250 tons per day) has an enhanced performance compared to the old processing line of this plant (with a capacity of 100 tons of waste per day). The new line reduced the amount of burial waste (the final residues of processing line) by 19. 84% compared to the old processing line. Also, with the launch of a new processing line, the amount of organic matter developed for the production of compost, which will be later used in the fermentation and aeration phase, is increased by 19. 39%. In addition, the ratio of extracted materials with economic value is increased by 0. 45%. In spite of improved performance of the new processing line, there is huge gap between its performance and standard RFTF model output.

Introduction: Alcohol production from molasses can lead to large amounts of wastewater that cause serious environmental concern. It is characterized with extremely high chemical oxygen demand (COD), biochemical oxygen demand (BOD) and dark brown color. This wastewater is poorly decolorized by the normal biological treatments such as activated sludge systems, aerated lagoons and anaerobic ponds. Various physicochemical treatments are also explored, such as activated carbon absorption process. But the high cast makes these methods hard to be applied. Therefore, it is significant to find a suitable way to treat this wastewater.Other providers are looking for other methods to convert this kind of dense wastewater into fertilizers with higher economic and social value. Composting this kind of wastewater is a biothermal aerobic process. During composting heat generated by the composition of the organic materials reduces the moisture content of the pile.

In recent years, the composting process has become an environmentally friendly process and a sustainable alternative to managing and recycling organic wastes. The purpose of this process is to achieve an organic product called "compost", which is used as an organic fertilizer and amendment in agricultural applications. Compost has many environmental, economic and agricultural benefits, the most prominent of which are discussed in this study. Factors affecting the process, including temperature, carbon to nitrogen ratio, moisture content, aeration rate and pH have been reviewed in detail. Strategies for improving process performance are also reviewed. Odor emission and the relatively high amount of time required to achieve quality product are among the challenges of this process, and the proposed approaches to encounter and address these challenges are reviewed in this paper. Finally, the standardization of the produced compost is explained.