How much does it cost to build a 2-stage sewage treatment tank for a small factory of 20-30 people in Sichuan area?

The secondary sewage treatment system is the pretreatment + biological treatment, about 30 people in a small factory, domestic sewage is about 6-7m?/d, I do not know what you produce, how much production wastewater, if you are dealing with this type of domestic sewage alone, to do the coefficient of 1.3, then the project investment of not more than 350,000, the specific needs to look at the conditions of construction and the specific requirements of the