Chemical wastewater treatment is a key problem in the field of industrial environmental protection. There are five core problems:
1. Difficulty in treating high-concentration harmful substances
Chemical wastewater often contains high-concentration organic matter (such as benzene, phenols), heavy metals (chromium, nickel, etc.), cyanide and other toxic components, as well as difficult-to-decompose polycyclic aromatic hydrocarbons. These pollutants are complex in type and have large concentration fluctuations, and traditional treatment processes are difficult to remove stably. For example, some toxic substances will directly kill microorganisms in the biochemical treatment system, resulting in the need to rely on advanced oxidation technology or membrane separation equipment, which greatly increases the treatment cost.
2. High salt and extreme pH problems
The salt content of some wastewater exceeds 3% (such as wastewater in the chlor-alkali industry), which seriously inhibits the activity of microorganisms and makes conventional biological treatment ineffective. At the same time, strongly acidic (pH <2) or strongly alkaline (pH >12) wastewater requires a large amount of neutralizing agents, which not only increases treatment costs, but may also produce new pollutants.
3. High sludge disposal costs
The sludge produced by physical and chemical treatments such as coagulation and sedimentation has a water content of up to 95%-98%, and contains heavy metals or organic toxins. Subsequent dehydration requires the use of high-energy consumption equipment such as plate and frame filter presses, and ultimately still requires landfill disposal according to hazardous waste standards, resulting in high sludge treatment costs for enterprises.
4. High operating energy consumption and reagent consumption
Fenton oxidation, ozone treatment, reverse osmosis membrane separation and other high-efficiency technologies require a large amount of hydrogen peroxide, membrane cleaning agents and other reagents, while high-pressure pumps and other equipment consume significant energy. The cost of treating a ton of water for this type of process can reach 30-100 yuan, which puts huge economic pressure on small and medium-sized enterprises.
5. Challenges in process adaptation and system stability
Wastewater characteristics in different industries vary significantly (such as high oil content in petrochemical wastewater and deep chromaticity in dye wastewater), and targeted process combinations need to be designed. In actual operation, fluctuations in water quality and quantity can easily lead to failure of the connection of treatment units, resulting in unstable effluent indicators and increasing the risk of meeting discharge standards.
