Phosphorus Removal from Industrial Wastewater

With the growth of industrial and agricultural production, the increase of population, and the extensive use of phosphorus containing pesticides and fertilizers, phosphorus pollution in water bodies is becoming increasingly serious. Phosphorus is one of the main nutrients required for crop growth, but if the phosphorus content in water exceeds 20mg/L, it will lead to eutrophication of the water, causing a large number of algae to reproduce, ultimately affecting the survival of aquatic organisms such as fish. Many algae also produce toxins, which affect human health through the food chain. Therefore, environmental protection departments require that wastewater must meet the secondary standard in GB8978-1996 "Comprehensive Wastewater Discharge Standard" before entering urban sewage networks.

Many treatment processes for phosphorus containing wastewater have been developed both domestically and internationally, mainly including chemical precipitation, crystallization, biological, and adsorption methods.

Chemical precipitation method for phosphorus removal is the earliest and most widely used method, and the removal rate of phosphorus mainly depends on the pH value. Generally, the phosphorus removal effect is better when the pH value is greater than 10. This method will produce a large amount of sludge, which needs to be treated later. If the treatment is not careful, it will cause secondary pollution. Crystallization method for phosphorus removal is the phenomenon of using phosphate ions, calcium ions, and hydroxide ions in wastewater to react and generate basic calcium carbonate, which precipitates on the phosphorus removal agent as a crystal nucleus. Although this method produces less sludge than chemical precipitation, the phosphorus removal efficiency is greatly affected when there is a large amount of organic matter in the wastewater. The most commonly used biological phosphorus removal process is the A/O process, which has a large amount of sludge return flow and high energy consumption; The cost for small and medium-sized sewage treatment plants is relatively high; The requirements for inlet water are high, with pH between 6-9 and BOD/COD greater than 0.3.

Adsorption method relies on the physical or chemical adsorption between adsorbents and phosphorus in wastewater to achieve the goal of removing phosphorus. After adsorption saturation, the adsorbent is regenerated to recover phosphorus resources. This method does not produce sludge, has simple treatment equipment, generally uses a fixed bed, has no other strict requirements for incoming water, and has stable treatment effects. The key to adsorption method lies in the performance of the special adsorbent itself.

The special phosphorus removal adsorbent developed by our company has excellent adsorption performance for both inorganic and organic phosphorus in wastewater, and can treat total phosphorus in wastewater to below 0.5ppm. High adsorption capacity, fast adsorption speed, and large single batch treatment capacity for wastewater. For resin saturated with adsorption, the use of regenerants can desorb and regenerate the organic phosphorus adsorbed on the resin, and the desorbed phosphorus can be recovered as a resource. The regenerated adsorbent can be reused repeatedly, with a long service life and stable performance.

Process flowchart

At present, our company has developed a special phosphorus removal adsorbent and treatment process for the phosphorus containing wastewater generated by a certain biological company in Zhejiang. The effluent can be treated to below 0.5ppm and directly reused in production, saving the production water cost of the enterprise. Compared with other methods, the operating cost is relatively low.