Chemical wastewater originates from multiple sources, primarily including the cleaning of chemical plant workshops, equipment cleaning, raw material leakage, and wastewater generated during pollutant treatment processes. In terms of classification, such wastewater can be divided into three categories: organic wastewater, inorganic wastewater, and organic-inorganic mixed wastewater. Consequently, it is of great significance to conduct effective Wastewater Monitoring and implement appropriate pretreatment measures prior to monitoring.
This type of wastewater is characterized by high chroma, irritability, and toxicity, with high pollutant content and complex compositions, rendering it difficult to degrade. Furthermore, the ecological restoration of water areas contaminated by such wastewater is highly challenging. The treatment of chemical wastewater typically involves three key stages: preliminary pretreatment engineering, biochemical treatment engineering, and advanced treatment engineering.
Enterprises such as pharmaceutical and petroleum refining industries are the main generators of high-chemical oxygen demand (COD) chemical wastewater. High-COD chemical wastewater is characterized by uneven discharge, significant fluctuations in water quality, strong corrosiveness, high toxicity, and high chroma. Once discharged into natural water bodies, it will severely damage the ecological environment. Moreover, harmful substances in chemical wastewater can contaminate water quality and accumulate in aquatic organisms; when humans consume contaminated fish and shrimp, chronic poisoning may occur, and in severe cases, irreversible diseases such as brain damage can be induced.
Against this background, how to effectively implement pretreatment work? Several common pretreatment methods are briefly introduced as follows:
1.Fenton Reaction Treatment: The Fenton reaction refers to an inorganic chemical reaction, in which organic compounds such as alcohols and esters are oxidized to inorganic states by a mixed solution of hydrogen peroxide and ferrous ions. This process can effectively remove refractory organic pollutants and is mainly applicable to the pretreatment of chemical wastewater such as printing and dyeing wastewater and coking wastewater.
2.Neutralization Precipitation Method: In cases where wastewater is difficult to degrade, coagulants such as alkalis are added to acidic chemical wastewater to initiate reactions, leading to the formation of water-insoluble suspended solids from chemical pollutants, thereby achieving the purpose of pretreatment.
