# Research Status and Development Trend of Wastewater Treatment Technology and Its Low Carbonization
## 3 Low-Carbon Sewage Treatment Technology
### Research Status
#### 3.1.2 Comprehensive Treatment of Low Carbon and Carbon Sequestration  
The traditional activated sludge treatment process requires a large amount of carbon source input and aeration, both of which increase the utilization of carbon. The extensive use of aeration consumes a large amount of external energy for sewage treatment, which leads to the waste of resources, and the generated CO2 and other gases increase air pollution. The traditional activated sludge method also produces a large amount of activated sludge, which represents a certain amount of sludge pollution, and does not conform to the concept of low carbonization. Compared with the activated sludge method, anammox technology can directly generate nitrogen by the reaction of nitrous nitrogen and ammonia nitrogen, which can greatly save the energy consumption of aeration and the input of carbon sources, but also reduce the production of sludge, greatly realizing the goal of low-carbon sewage treatment. It is a relatively clean biological nitrogen removal water treatment technology and has a good development prospect. The annual energy consumption of the Sheboygan Wastewater Treatment Plant in the United States accounts for 3% of the total social energy consumption and is the most energy-consuming public facility [72]. In order to achieve the goals of energy self-sufficiency in wastewater treatment and sustainable utilization of resources, the United States Water Environment Research Foundation (WERF) has indicated that all wastewater treatment plants in the United States must achieve carbon-neutral operation by 2030 [73]. The Sheboygan Wastewater Treatment Plant is the first to start the practice of carbon neutral operation. Based on the operational goal and implementation plan of \"zero energy consumption\" of the \"Wisconsin Focus Energy\" project, the Sheboygan Wastewater Treatment Plant carried out a series of energy recovery plans from 2002 to 2011, adding 12 30 kW micro gas turbines and 4 heat recovery treatment plants. By 2012, the plant could generate 16,800 kW-h/d of electricity and 16,120 kW-h/d of heat by using cogeneration technology, which offset about 90% of the power consumption and 85% of the heat demand of the sewage plant, basically achieving energy self-sufficiency. In terms of sludge disposal, the equipment for sludge enrichment and dewatering disposal has been upgraded to achieve dehydration treatment with lower energy consumption. At the same time, the treated sludge can make up for the energy consumption of sludge disposal through incineration and power generation, and can also be used for farmland soil remediation, building materials, etc., to fully realize the sustainable development concept of low carbonization and resource recycling [74; 75]. In the process of treating part of the industrial wastewater, additional nutrients need to be added, and underutilized nutrients can be recycled to reduce carbon loss. The wastewater discharged is to the standard of reuse for plant greening and equipment washing. In addition, the sewage plant self-funded nearly 1.1 million US dollars for a series of energy-saving upgrading and operation optimizations, updating the pump and blower and other mechanical equipment for energy savings of 20 and 13% respectively, installing a flow control valve (energy saving 17%), updating the digestion tank heating equipment, upgrading the programmable logic controller (PLC), supervisory control and data acquisition (SCADA) and so on, greatly reducing energy consumption. By 2013, the Sheboygan Sewage Treatment Plant had achieved a ratio of electricity production to electricity consumption of 90-115% and a ratio of heat production to heat consumption of 85-90%, basically close to the goal of carbon neutral operation. The technology of the Sheboygan Wastewater Treatment Plant is worth studying for domestic sewage treatment plants.