Thai Nguyen city is urban area of category 2 with the population of 256,346 and the population density of 1,288 people/km2. Water supplying for the City's residents is mainly provided from two Water Treatment Factories including Tich Luong (with Capacity of 20,000m3/day and preparedly reach 40,000m3/day) and Tuc Duyen (with Capacity of 10,000m3/day). Besides, Civilians also exploit a great volume of raw water from wells and other sources. Then the City will averagely discharge domestic wastewater into the environment, approximately, 30,000 m3 per day. However, neither in the City nor the rest of Province has an operated factory acting for domestic wastewater treatment. The untreated domestic wastewater directly come into the environment, simultaneously, will leave negative impacts on people and ecosystem as well. To design and construct a domestic wastewater treatment system for the City is a need contributing to the development of the Landlord.