A bio-digester STP is an anaerobic (oxygen free) multi-compartment tank, which digests sewage waste biologically without any format of energy. It works on the gravitational force and converts sewage waste into odour less water and methane gas with COD and the BOD less than 100 which is fit for horticulture purpose.
The water flowing out of Bio- STP is then passed through a aeration process using the Reed Bed technology to further reduce the TDS/ BOD and COD levels . The BOD and COD of value less than 30 can easily be achieved by using this process .
The above system can be used in hotels / resorts / Societies/Housing complexes/farmhouses/hospitals etc.
Process :
The process of bio-degradation of human waste used in the present technology is carried out in strict anaerobic environment (devoid of oxygen) by anaerobic microbial consortium. It involves multiple biochemical steps and is of complex nature. These steps are sequential in nature and interdependent. For proper functioning of the bio-digester, they need to work in equilibrium. As the final outcome is methane and CO2 which is produced by methanogenic bacteria, it is rate controlling step and relatively very slow. The human waste is composed of polymers (carbohydrates, proteins, fats etc.). By hydrolysis they are broken down to monomers with the help of enzymes produced by hydrolytic bacteria. In the second step (acedogenesis) the monomers are converted to long chain fatty acids, alcohol etc. In the third step these fatty acids are converted to the simplest molecules like acetic acid, methanol, CO2 and hydrogen (acetogenesis). In the final step (methanogenesis) they are converted into methane and CO2.
Advantages :
• Generates colorless, odorless inflammable Bio gas(can be used for cooking heating) and absolutely clear odorless water. Water is full of nutrients and minerals and is good for irrigation purpose of nearby gardens, lawns etc.
• 100% maintenance free, continuous Biological process.
• Complete elimination of pathogens.
• Economically viable.
• No dependence on the limited and costly conventional energy sources.
• Can be installed and made operational in least Time-duration.
• Inoculums charging is only once during the entire life of Bio Digester System.
• No need of connectivity to the sewage line, septic tank. No disposal of sludge is required.