The role of septic tanks
The septic tank is a basic sludge treatment facility also a pretreatment facility for domestic sewage. Its functions are shown in:
1. Ensure the environmental sanitation of the living community avoid the spread of domestic sewage pollutants in the living environment.
2. In the anaerobic decayed working environment of septic tanks, kill mosquitoes, flies eggs.
3. Temporary storage of sludge. Organic sludge undergoes anaerobic decomposition. The matured organic sludge can be used as agricultural fertilizer.
4. Pretreatment of domestic sewage (primary treatment), precipitation of impurities, hydrolysis of macromolecular organics into small molecular organics such as acids alcohols to improve subsequent sewage treatment.
Process principle
Septic tank is a treatment facility that uses the principles of sedimentation anaerobic fermentation to remove suspended organic matter in domestic sewage. It is a primary transitional living treatment structure. Domestic sewage contains a large amount of feces, paper scraps, pathogens... The concentration of suspended solids is 100~350mg/L, the concentration of organic matter CODCr is between 100~400mg/L, the concentration of suspended organic matter BOD5 is 50~200mg/L. L.
Sewage enters the septic tank for 12 to 24 hours of precipitation, which can remove 50% to 60% of the suspended solids. The deposited sludge is decomposed by anaerobic fermentation for more than 3 months to decompose the organic matter in the sludge into stable inorganic matter. The perishable raw sludge is transformed into stable cooked sludge, which changes the structure of the sludge. Reduce the moisture content of the sludge. The sludge is regularly removed transported out, landfilled used as fertilizer.
