Septic tank calculation and, the total number of people in the septic tank design n, the daily sewage quota per person Q, the residence time of sewage in the septic tank T, and the percentage of the number of people actually using sanitary appliances to the total number of people in the design ��, The moisture content of sludge b=95, the moisture content of thickened sludge c=90, the sludge reduction coefficient K during the corruption period �� 0.8, the cleaning cycle T of the septic tank is determined by the design according to 90d, 180d, 360D, the volume coefficient of the cooked sludge after cleaning is 20, and the sludge volume per person per day of the combined system a = 0.7l/ person.D; The sludge volume per person per day of the diversion system is related to a = 0.4l/ person.D

The parameters are determined according to page 71-72 of gb50015-2003p

The volume (W) of septic tank is composed of sewage volume (W1) and sludge volume (W2)

W1=N*q*t*��/ (24*1000)

W2=1.2*(a*N*��*T(1-b)*k)/((1-c)*1000)

The specific number of sanitary appliances can not be calculated accurately. The total number of people should be determined.

Guidance is given in the guidelines for toilet renovation in rural areas for your reference