Biogas slurry and residue treatment

Biogas slurry and biogas residue are byproducts produced during the biogas fermentation process. They are rich in organic matter, nitrogen, phosphorus, potassium and other nutrients as well as microbial metabolites, and have high agricultural utilization value. However, biogas slurry and biogas residue that are not properly treated may cause environmental pollution problems. Therefore, reasonable biogas slurry and biogas residue treatment mainly includes the following aspects: 1. Biogas slurry treatment and utilization - Irrigation and fertilization: Biogas slurry can be directly used for farmland irrigation and used as liquid fertilizer. Its rich organic nutrients and trace elements help improve soil structure, enhance soil fertility and promote crop growth. However, before use, the crop type, growth stage, soil conditions and nutrient concentration and pH of biogas slurry should be considered, and appropriate amount should be applied to avoid excessive burning of seedlings or soil salinization. - Dilution spraying: After proper dilution, biogas slurry can be used as foliar fertilizer spraying to provide nutrients for crops. At the same time, some beneficial microorganisms and organic acids help prevent and control pests and diseases. - Bioconcentration: Through membrane separation, evaporation concentration and other technologies, the nutrients in biogas slurry are concentrated to make liquid or solid fertilizers, which improves the convenience of transportation and application. - Storage in biogas pools: Biogas that cannot be used directly in the short term can be stored in special biogas pools. After natural sedimentation and microbial stabilization, ammonia nitrogen volatilization and organic matter oxidation loss can be reduced, and it can be applied when needed for farming. 2. Treatment and utilization of biogas residues - Composting: Biogas residues are mixed with crop straw, garden waste, etc., and further degraded organic matter, killed pathogens and parasite eggs through aerobic composting or anaerobic composting, and generated stable and long-lasting biofertilizers. Conditioners (such as lime, phosphate rock powder, etc.) can be added during the composting process to adjust the carbon-nitrogen ratio and pH value to promote the composting process. - Direct return to the field: After dehydration, biogas residues are applied to farmland as base fertilizer or topdressing to supplement soil organic matter and nutrients. Pay attention to controlling the application amount to avoid soil compaction and excess nutrients. - Biomass fuel: Biogas residues can be made into biomass pellet fuel or biochar for heating or power generation through drying, crushing, molding and other processes. - Feed: Biogas residues that do not contain antibiotics, heavy metals and other harmful substances can be used as feed additives or directly fed to livestock and poultry, especially ruminants, after harmless treatment, but they must follow strict hygiene and nutrition standards. 3. Comprehensive utilization model - Circular agriculture: Biogas slurry and biogas residues are used for recycling in planting and breeding industries, such as biogas slurry for irrigation or foliar spraying, and biogas residues for composting or direct return to the field, to achieve a virtuous cycle of agricultural waste resource utilization and agricultural production. - Ecological gardening: Biogas slurry and biogas residues are also widely used in horticultural production such as flowers, fruits and vegetables, as base fertilizer, topdressing or foliar fertilizer to improve product quality and yield. - Biomass energy base: Biogas slurry and biogas residues produced by large-scale biogas projects can be centrally processed to produce high-quality organic fertilizers, which can be supplied to surrounding farmlands or sold as commercial fertilizers, forming an industrial chain combining biomass energy and organic agriculture. In general, the key to the treatment of biogas slurry and biogas residues is to realize their resource utilization, convert them into valuable fertilizers, feed or energy products, while reducing environmental pollution and promoting sustainable agricultural development. In actual operations, appropriate treatment methods and utilization channels should be selected based on local resource conditions, market demand and technological maturity.