Case analysis
CASE ANALYSIS
Product Classification: Chemical Wastewater Treatment Engineering
Project Name: Sewage Treatment Project of a Chemical Enterprise in Ningxia
Type of pollution control: chemical wastewater and daily sewage treatment scale: daily treatment capacity of 180 tons. Implementation standard: comprehensive primary discharge standard
Treatment process: using physicochemical anaerobic MBR constructed wetland treatment process
Project Description: Chemical Sewage Treatment Project, the treatment water volume of the project is 180m/d, and the treatment effect reaches the national first-class discharge standard.

Characteristics and difficulties of chemical wastewater treatment
CHARACTERISTICS AND DIFFICULTIES OF CHEMICAL WASTEWATER TREATMENT
The basic characteristics of chemical wastewater are:(1) the water quality composition is complex, there are many by-products, and the reaction raw materials are often solvents or compounds with ring structure, which increases the difficulty of wastewater treatment;(2) the content of pollutants in wastewater is high, which is caused by incomplete reaction of raw materials and a large number of solvent media used in raw materials or production entering the wastewater system;(3) there are many toxic and harmful substances, many organic pollutants in fine chemical wastewater are toxic and harmful to microorganisms, such as halogen compounds, nitro compounds, dispersants or surfactants with bactericidal effect, etc.;(4) there are many biodegradable substances, low B/C ratio and poor biodegradability;(5) high chroma of wastewater. If it is not treated or not treated immediately discharged into water or used for irrigation, it will pollute the environment and affect people's health.

Inlet water quality and outlet water quality
WATER QUALITY AND WATER QUALITY

Solutions and technical features
SOLUTIONS AND TECHNICAL FEATURES
According to the actual investigation of the chemical enterprise, through on-site investigation and data search, as well as the comprehensive analysis of the monitoring and teaching data of the local environmental monitoring station, the technical group of our company has formulated the corresponding process flow for the chemical enterprise, which effectively solves the treatment problem of chemical wastewater and domestic sewage of the chemical enterprise.
A chemical enterprise is a medium-sized chemical enterprise with the research and development, production and application of chemical fiber oil agent, special surfactant and polyether series products as the core. Its products are various. The wastewater discharged in the production process mainly contains pollutants such as alcohol, ether, alkane, organic acid, etc., with complex composition and large water quality change, which is a difficult chemical wastewater to treat. The effluent is subject to the first-level standard in the Comprehensive Wastewater Discharge Standard (GB8978-1996). With the expansion of the production scale of the enterprise and the improvement of environmental protection awareness, the original facilities can no longer meet the needs of enterprise development. Therefore, the enterprise proposes to build a set of sewage treatment facilities with a treatment scale of 180m ³/d, and requires the effluent to be reused for equipment cleaning and greening. Ground flushing water, etc. After investigating the water quality and quantity of the company's wastewater, it is proposed to collect bromobutane wastewater with high COD and poor biodegradability and high concentration wastewater such as EO and PO pressure relief water separately for pretreatment, and then mix with other wastewater for retreatment.
Considering the treatment effect and treatment cost, it is decided to adopt ozone advanced oxidation technology as the pretreatment process of high concentration wastewater, and the comprehensive wastewater adopts the treatment process of physical and chemical anaerobic MBR artificial wetland.

Treatment process
PROCESS FLOW

Effect after treatment
THE EFFECT AFTER TREATMENT
The effluent quality of the sewage treatment system designed for the chemical enterprise is good, the main water quality index can meet the discharge standard, which can well adapt to the unstable water quality of the influent, and the effluent of the system can reach the first level standard of comprehensive sewage discharge, which effectively solves the reality of high COD in this kind of wastewater. According to the actual requirements and design process, the treatment process of physicochemical anaerobic MBR constructed wetland is adopted to improve the water quality, meet the requirements of effluent standard and ensure the long-term stable operation of the sewage treatment system.

Conclusion
CONCLUSION
(1) In view of the characteristics of the wastewater of this project, such as various types, complex components, high COD and large changes in water quantity and quality, the scheme of quality collection and separate treatment is adopted. The wastewater with high COD and difficult treatment is collected separately. First, the concentration of some pollutants is reduced through pretreatment to improve the biodegradability of the wastewater, and then mixed with other wastewater for treatment.
(2) The high-concentration wastewater of this project adopts ozone oxidation treatment process, and the comprehensive wastewater adopts the compound treatment process of anaerobic MBR constructed wetland. The engineering practice shows that the system has reliable operation, strong impact load resistance and remarkable treatment effect, and the effluent quality can meet the requirements of flushing water for the ground and equipment in the workshop of the enterprise.