Wastewater reuse has several technical difficulties to be overcome: clogging, corrosion, sewage treatment equipment direct heat exchange efficiency. Sewage composition is relatively fixed, Ledong Li Autonomous County sewage treatment equipment, mainly contains carbohydrates, protein, amino acids, fat and other organic matter, sewage treatment equipment principle, more suitable for the growth of bacteria, sewage treatment equipment prices, become bacteria, virus survival and reproduction sites; but generally do not contain toxic sewage, and has a certain fertilizer, can be used to irrigate farmland.