Classification of industrial wastewater:

1. According to the chemical properties of the main pollutants contained in industrial wastewater, those containing inorganic pollutants are classified as inorganic wastewater, while those containing organic pollutants are classified as organic wastewater. For example, electroplating wastewater and mineral processing wastewater are inorganic wastewater; The wastewater from food or petroleum processing is organic wastewater.

2. Classified by the products and processing objects of industrial enterprises, such as metallurgical wastewater, papermaking wastewater, coking gas wastewater, metal pickling wastewater, chemical fertilizer wastewater, textile printing and dyeing wastewater, dye wastewater, tannery wastewater, pesticide wastewater, power plant wastewater, etc.

3. Classify the main components of pollutants in wastewater, such as acidic wastewater, alkaline wastewater, cyanide wastewater, chromium wastewater, cadmium wastewater, mercury wastewater, phenolic wastewater, aldehyde wastewater, oily wastewater, sulfur-containing wastewater, organic phosphorus wastewater, and radioactive wastewater.

The discharge of industrial wastewater is large, with a wide range of pollution and complex discharge methods, including intermittent discharge, continuous discharge, regular discharge, and irregular discharge; There are various types of pollutants in industrial wastewater, with large fluctuations in concentration; Industrial wastewater contains a large amount of nutrients such as nitrogen, phosphorus, and potassium, which can promote the growth of algae and consume dissolved oxygen in water, causing eutrophication and pollution of water bodies. The suspended solids content in industrial wastewater is very high, up to 3000mg/L, which is 10 times that of domestic wastewater.

The general monitoring indicators for industrial wastewater include suspended solids, COD, volatile phenols, cyanide, heavy metals, sulfides, pH, ammonia nitrogen, petroleum, etc

Sampling time and frequency of industrial wastewater:

The pollutant content and discharge amount of industrial wastewater often vary greatly with different process conditions and operating rates, so the selection of sampling time, cycle, and frequency is a complex problem. Pollution sources with a general wastewater discharge volume of ≥ 5000t/d require the installation of automatic online water quality monitoring instruments, which can continuously and automatically monitor and monitor at any time; The main pollution source with wastewater discharge of 1000-5000t/d requires the installation of proportional automatic samplers and flow measuring devices, and monitoring once a day; Pollution sources with wastewater discharge ≤ 1000t/d are monitored 3-5 times per month. Synchronous monitoring of water quality and quantity; The monitoring frequency of unstable pollution sources in production depends on the production cycle and pollution discharge situation.