Effect of Dissolved Ca²⁺ and Mg²⁺ in Excess Sludge on Phosphorus and Nitrogen Recovery under Acidic-Base Condition

Abstract:

Calcium(Ca²⁺) and magnesium(Mg²⁺) ions dissolve out in the process of getting phosphorus-rich solution by hydrolysis and acidification of sludge. To study the effect of dissolved Ca²⁺ and Mg²⁺ on nitrogen and phosphorus recovery, this paper investigated the dissolution of NH₄⁺, PO₄^3-, Ca^₂+ and Mg²⁺ in the process of hydrolysis and acidification of excess sludge under the condition of different pH and discussed the impact of Ca²⁺ and Mg²⁺ ions on the recovery of nitrogen and phosphorus by struvite precipitation method. The result indicates that the adjusting of acid-base environment can contribute to the release of NH4⁺-N and PO₄^3--P in the process of hydrolysis and acidification and pH=3 is the best and the best reaction time is 5 days. The fact that the molar ratio Ca²⁺: Mg²⁺ is greater than 1 has influence on nitrogen and phosphorus recovery but whether additional magnesium existed or not has little effect on the percent recovery of nitrogen and phosphorus when pH=3.

• Periodical: Advanced Materials Research (Volumes 726-731)
• Pages: 2670-2676
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.726-731.2670
• Online since: August 2013
• Authors: Hong Ying Yuan*, Ting Wang, Yi Chen, Li Qi, Si Fang Niu
• Keywords: Hydrolysis and Acidification, Magnesium Addictive, pH, Phosphorus and Nitrogen Recovery, Release of Ca²⁺ and Mg²⁺, Struvite Precipitation

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