The composition of sludge is complex, with various sources and types. At present, the main methods of sludge disposal in the world are sludge landfill, sludge incineration, land resource utilization, and other comprehensive treatment methods. Several disposal methods have their advantages and differences in application, as well as relative shortcomings. For example, sludge landfill will have problems such as difficult mechanical compaction, difficult filtrate treatment, and serious odor pollution; sludge incineration has problems such as high energy consumption, high treatment costs, and the production of harmful dioxin gases; The utilization is to deal with problems such as long cycle and large area. On the whole, the realization of sludge harmlessness, reduction, resource utilization, and stabilization treatment is an environmental problem that needs to be continuously tackled and improved.
Sludge aerobic composting technology:
In recent years, sludge aerobic composting technology has been applied to sludge disposal. It is a harmless, volume-reducing, and stabilizing sludge comprehensive treatment technology. Because of its many utilization methods for fermented products (forest land utilization, landscaping utilization, landfill cover soil, etc.), low investment and operation costs, a Wide range of applications and other characteristics are widely concerned. There are three common composting processes, namely: windrows type, bin/trough type, and reactor. The fundamental principle is that the microbial community decomposes and converts the organic matter in the sludge into carbon dioxide, water, inorganic matter, and biological cell matter under suitable nutrient, moisture and ventilation conditions, releasing energy at the same time, and improving the solid waste into the stable. Humus, improve sludge fertilizer content.
Basic requirements for sludge composting:
There are many sources of sludge, but some are not suitable as raw materials for composting. First, the following conditions need to be met:
1. The heavy metal content does not exceed the standard; 2. It is biodegradable; 3. The organic matter content cannot be too low, at least more than 40%.
The technical principle of sludge composting:
The principle is the process of humification of organic solid wastes by the action of aerobic microorganisms under aerobic conditions. In this process, the soluble substances in the sludge are directly absorbed by the microorganisms through the cell walls and cell membranes of the microorganisms; secondly, the insoluble colloidal organic substances are adsorbed outside the microorganisms, decomposed into soluble substances by the extracellular enzymes secreted by the microorganisms, and then infiltrated into the cells. Microorganisms carry out catabolism and anabolism through their own life metabolic activities, oxidize part of the absorbed organic matter into simple inorganic substances, and release the energy required for biological growth activities; synthesize another part of organic matter into new cellular substances, so that microorganism’s Growth and reproduction, producing more organisms.
Hybrid preprocessing:
Adjust the particle size, moisture, and carbon-nitrogen ratio of the material, and add bacteria at the same time to promote the rapid progress of the fermentation process.
Primary fermentation (composting):
Decompose volatile substances in waste, kill parasite eggs and pathogenic microorganisms, and achieve the purpose of harmless. When the moisture content is reduced, the organic matter is decomposed and mineralized to release N, P, K, and other nutrients, and at the same time, the properties of the organic material become loose and dispersed.
Secondary fermentation (decomposed):
The organic solid waste after the first compost fermentation has not yet reached maturity and needs to continue to undergo secondary fermentation, that is, aging. The purpose of aging is to further decompose, stabilize and dry the remaining macromolecular organic matter in the organic matter to meet the requirements of the subsequent fertilizer production process.
Post time: Jul-22-2022