The treatment part describes the treatment technologies that are generally appropriate for the ward level and city level. The CAPEX, OPEX, land and energy requirements of the technologies of the treatment group are generally higher than those of the storage group. The treatment group is divided into four categories: (1) primary treatment (separation of solid–liquid), (2) treatment of effluent, (3) treatment of sludge and (4) treatment of post-effluent.