Architecture and functional groups of biofilms during composting with and without inoculation

Management of water-based paint sludge originating from the automotive industry via composting

Water-based paint sludge generated from the automotive industry is considered a hazardous waste due to its high carbon content and is challenging and costly to manage. This study investigates the management of water-based paint sludge through the composting process, considering its high carbon content. The water-based paint sludge was composted in five separate reactors with the addition of treatment sludge from the same industry as co-substrate and inoculum, as well as sunflower stalks as a bulking agent. The ratio of paint sludge added to the compost mixtures varied between 40% and 80%. The highest temperature was achieved in reactors where industrial sludge was added, and the bulking agent was used at a rate of 20% (R3 and R5). The most efficient composting process was conducted with the addition of 60% water-based paint sludge, 20% treatment sludge, and 20% sunflower stalks (w/w, wet weight basis) (R3). During this process, reductions in organic matter content were observed due to organic matter mineralization, resulting in a decrease in moisture during the maturation phase and consequently reducing waste volumes. The composting process can be a useful tool in addressing the challenges of paint sludge management. Utilizing the composting process not only reduces waste volumes, thereby minimizing environmental impacts, but also offers a sustainable approach to paint sludge management by lowering disposal costs. It is also possible to achieve more effective results by composting paint sludge with different recipes and the use of various bulking agents.Implications: Composting is a method that can be used to achieve stabilization, reduce the quantity, and enable biodrying of water-based paint sludge generated from the automotive industry. In this study, different ratios of paint sludge were mixed with treatment sludge from the same industry as co-substrate and inoculum, while sunflower stalks were added as a bulking agent, and a composting process was conducted. The addition of industrial wastewater treatment sludge and sunflower stalks has increased the efficiency of the paint sludge composting process. In the management of paint sludge, the composting process has emerged as a significant alternative that reduces disposal costs and environmental impacts.

Effect of multi-stage inoculation on the bacterial and fungal community structure during organic municipal solid wastes composting

In this study, PCR-DGGE method was applied to investigate the impact of multi-stage inoculation treatment on the community composition of bacterial and fungal during municipal solid wastes (MSW) composting process. The results showed that the high temperature period was extended by the multi-stage inoculation treatment, 1day longer than initial-stage inoculation treatment, and 5days longer than non-inoculation treatment. The temperature of the secondary fermentation increased to 51°C with multi-stage inoculation treatment. The multi-stage inoculation method improved the community diversity of bacteria and fungi that the diversity indexes reached the maximum on the 17days and 20days respectively, avoided the competition between inoculations and indigenous microbes, and enhanced the growth of dominant microorganisms. The DNA sequence indicated that various kinds of uncultured microorganisms with determined ratios were detected, which were dominant microbes during the whole fermentation process. These findings call for further researches of compost microbial cultivation technology.