Solar composting greenhouse for organic waste treatment in fed-batch mode: Physicochemical and microbiological...

Composting is a sustainable means of managing organic waste, and solar composters offer a viable solution in rural areas lacking connection to municipal power supplies. This study tracked the physicochemical and microbiological changes that occur in a solar composting greenhouse during the treatment of food and green cellulosic waste in fed-batch mode, which remain poorly understood. Solar composting greenhouse performed well on waste reduction and nutrient retention, resulting in a 45.0-58.8% decrease in feedstock volume over 12-day composting cycles, a 41% removal in dry matter after three batches of composting, and 29.5%, 252.9% and 96.6% increase in the nitrogen, phosphorus and potassium content respectively after 42 days of composting. Batch feeding and composting jointly influenced microbiological succession by altering the physicochemical properties of compost. The contents of nitrogen and phosphorus, pH, and electrical conductivity significantly accounts for variations in culturable microbial populations. The succession of dominant bacterial genera such as Lactobacillus, Pseudoxanthomonas, Bacillus, and Pseudomonas were closely related to pH, cellulose, NH₄⁺-N, carbon content, and temperature. In addition, Pichia kudriavzevii, Thermomyces lanuginosus, and Scopulariopsis brevicaulis successively became the dominant fungal species during composting. Preliminary compost quality assessments showed that solar composting greenhouse has a high potentiality to transform organic waste into organic fertilizer. Additionally, corresponding purposeful suggestions were proposed for future optimization in this system, mainly from a microbiological aspect.