Introduction
Industrial wastewater refers to the wastewater, waste liquid, and sewage generated during industrial production processes, which primarily contains pollutants lost from industrial operations. Such wastewater poses a threat to water bodies, and prolonged pollution can adversely impact the ecological environment and human health. Thus, relevant authorities mandate rigorous wastewater monitoring to ensure real-time compliance of discharge indicators. This paper examines the classification and treatment strategies of industrial wastewater.
Classification of Industrial Wastewater
Industrial wastewater can be classified into three main categories:
2.1 Classification by Chemical Nature of Pollutants
Wastewater is categorized based on the dominant type of pollutants:
– Inorganic wastewater: Characterized by inorganic pollutants (e.g., wastewater from electroplating and mineral processing).
– Organic wastewater: Dominated by organic pollutants (e.g., wastewater from food processing and petroleum refining).
2.2 Classification by Production Process
Wastewater is classified according to the product processing scope of enterprises, including papermaking wastewater, chemical fertilizer wastewater, metal acid wastewater, metallurgical wastewater, fuel wastewater, and textile printing-dyeing wastewater.
2.3 Classification by Key Pollutant Components
This classification explicitly identifies the primary pollutants, such as wastewater containing heavy metals (chromium, cadmium, mercury, etc.), acid, alkali, organic phosphorus, or oil.
Notably, the first two classification methods do not specify pollutant components, thus failing to directly indicate the harmfulness of wastewater. In contrast, the third method clarifies key pollutants, whose concentrations can directly reflect the pollution level and potential hazards of the wastewater.
Treatment Strategies for Industrial Wastewater
3.1 Source Reduction via Harmless Processes
Prioritize the adoption of non-toxic production technologies to minimize the generation of toxic and hazardous wastewater at the source.
3.2 Strict Control During Production
If toxic raw materials are unavoidable, implement strict operational supervision, optimize processes and equipment, and eliminate leaks to reduce pollutant loss.
3.3 Diversion and Resource Recovery for Highly Toxic Wastewater
For highly toxic wastewater (e.g., wastewater containing heavy metals, high-concentration phenols, or cyanides), implement separate collection. This facilitates targeted treatment and recovery of valuable substances.
3.4 Treatment and Reuse of Low-Pollution Wastewater
For large-volume, low-pollution wastewater, conduct appropriate treatment for recycling to avoid direct discharge (which may contaminate urban sewers). If discharge is necessary, perform disinfection first, followed by online monitoring of indicators; discharge is only permitted upon confirmation of compliance.
3.5 Targeted Treatment for Refractory Toxic Wastewater
Refractory toxic wastewater may be discharged into urban sewage treatment systems for further processing. However, wastewater containing non-biodegradable toxic substances should be treated separately to prevent adverse impacts on municipal treatment facilities.
