Method for removing phosphorus in concentred and dewatered sludge water by virtue of deeply-dewatered sludge water

Abstract

The invention discloses a method for removing phosphorus in concentred and dewatered sludge water by virtue of deeply-dewatered sludge water. The method comprises the following steps of: pre-precipitating the deeply-dewatered sludge water and the concentred and dewatered sludge water respectively, and removing suspended matters in the two types of sludge water; then measuring the pH values of the two types of sludge water and the concentrations of phosphorus respectively; adding the deeply-dewatered sludge water in the concentred and dewatered sludge water in a certain ratio; stirring and standing; then taking the supernatant and measuring the pH value of the effluent and the concentration of phosphorus. According to the method disclosed by the invention, the mutual reactions of sludge water generated in different sludge treatment phases of a sewage treatment plant can be utilized, precipitates are formed by the metal ions of the deeply-dewatered sludge water and the phosphorus of the concentred and dewatered sludge water, solid-liquid separation is performed on the precipitate particulate matters and the supernatant by standing, the effluent is discharged, and the formed phosphorus-containing precipitates are recycled; meanwhile, the pollutant loads of metal ions and phosphorus in the sludge water can be reduced, and the pollutant burden of the backflow of the sludge water to a front-end sewage treatment system or the entrance of the sludge water in a sludge water bio-treatment process is reduced; therefore, the method has the practical significance of treating waste with waste.

Description

technical field [0001] The invention belongs to the field of sewage sludge treatment, and in particular relates to a method for removing phosphorus in sewage, in particular to a method for removing phosphorus in concentrated dewatered sludge water by using deep dewatered sludge water. Background technique [0002] At present, the national sewage treatment capacity has increased from 11.4 billion m in 1999 3 increased to 49.6 billion m in 2011 3 , and the sewage treatment rate also increased from 31.9% in 1999 to 80.5% in 2011, and the amount of sludge generated has also increased significantly. However, the excess sludge has a high moisture content and a large volume, which is not suitable for direct transportation and disposal. Thickening and dehydration treatments reduce the volume of sludge. The wastewater generated during the sludge thickening and dewatering process is called concentrated dewatered sludge water. Under the mechanical concentration and high-speed centri...

AI Technical Summary

Problems solved by technology

Under the mechanical concentration and high-speed centrifugal dehydration of the sludge, the interstitial water is squeezed out, and part of the extracellular polymer is dissolved. At the same time, the phosphorus in the sludge is released into the sludge water under the concentration and dehydration anaerobic environment, and the concentration of phosphorus in the sludge water is much lower than If the sludge water is directly returned to the water inlet, the phosphorus-accumulating bacteria will absorb the phosphorus in the sewage into the sludge under aerobic conditions, and the phosphorus-accumulating bacteria will release the phosphorus into the sludge under the concentration and dehydration anaerobic conditions. In the sludge water, the sludge water is returned to the sewage biological treatment system. In such a cycle, the phosphorus in the sewage is not really removed, and the phosphorus load in the biological treatment system is high. The concentration of phosphorus in the effluent of the sewage plant cannot meet the relevant discharge standards and is discharged into the river. It will cause eutrophication of water body and pollute the environment

[0003] Phosphorus removal methods include chemical phosphorus removal, physical phosphorus removal and biological phosphorus removal. Although biological phosphorus removal is cheap, its phosphorus removal rate is low. At the same time, it has strict requirements on the reaction environment. Once the conditions change, the treatment effect will be unstable; Phosphorus removal by physical methods such as dialysis or reverse osmosis has high treatment costs and is not convenient for widespread application; chemical phosphorus removal is generally done through PO 4 3- with Al 3+ , Fe 3+ , Ca 2+ or Mg 2+ etc. chemical precipitation to remove

[0004] At present, the sludge moisture content can usually be reduced to about 80% through the traditional thickening and dehydration process, but the high moisture content of the dehydrated cake in this process leads to high energy consumption in the subsequent process, which makes it difficult to meet the requirements of treatment and disposal, resulting in serious secondary pollution

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