Sewage treatment is the process of removing contaminants from wastewater, primarily from household sewage. It includes physical, chemical, and biological processes to remove these contaminants and produce environmentally safe treated wastewater (or treated effluent). A by-product of sewage treatment is usually a semi-solid waste or slurry, called sewage sludge that has to undergo further treatment before being suitable for disposal or land application.
Initial dosage is 50ppm which is to be applied on a daily basis for 7-10 days.
Then you can evaluate and apply according to your desired COD & BOD level.