Effective removal of ammonia nitrogen from waste seawater using crystal seed enhanced struvite precipitation technology with response surface methodology for process optimization
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Traditional biological treatment was not effective for removing nitrogen from saline wastewater due to the inhibition of high salinity on biomass activity. In this context, a method of removing ammonia nitrogen from waste seawater was proposed by struvite precipitation which was enhanced by seeding technique. The abundant magnesium contained in waste seawater was used as the key component of struvite crystallization without additional magnesium. The effects of pH and P:N molar ratio on ammonia nitrogen removal efficiency were studied. The results showed that optimum pH value was in range of 8.5–10 and the P:N molar ratio should be controlled within 2:1–3:1. XRD and SEM-EDS analyses of the precipitates proved that Ca2+ and excess Mg2+ contained in waste seawater inhibited the struvite crystallization by competing PO4 3− to form by-products. Then, seeding technique for enhancing the struvite crystallization was investigated, and the results indicated that using preformed struvite as crystal seed significantly improved the ammonia nitrogen removal efficiency, especially when initial ammonia nitrogen concentration was relatively low. Moreover, response surface optimization experiment following a Box-Behnken design was conducted. A response surface model was established, based on which optimum process conditions were determined and interactions between various factors were clarified. At last, economic evaluation demonstrated this proposed method was economic feasible.
KeywordsStruvite precipitation Waste seawater Ammonia nitrogen removal Crystal seed Response surface optimization
This study was supported by the National Natural Science Fund of China (No. 51408158), the Fundamental Research Funds for the Central Universities (No.HIT.NSRIF.2016098), and the scientific research foundation of Harbin Institute of Technology at Weihai (HIT(WH)201403).
- APHA (2005) Standard methods for the examination of water and wastewater, APHA, AWWA and WPCF, WashingtonGoogle Scholar
- Çelen I, Türker M (2001) Recovery of ammonia as struvite from anaerobic digester effluents. Environ Technol 22:1263–1272Google Scholar
- Huang HM, Xu CL, Zhang W (2011) Removal of nutrients from piggery wastewater using struvite precipitation and pyrogenation technology. Bioresour Technol 102:2523–2528Google Scholar
- Li W, Ding X, Liu M, Guo Y, Liu L (2012) Optimization of process parameters for mature landfill leachate pretreatment using MAP precipitation. Front Env Sci Eng 6:892–900Google Scholar
- Siegrist H (1996) Nitrogen removal from digester supernatant - Comparison of chemical and biological methods. Water Sci Technol 34:399–406Google Scholar
- Teng-rui L, Xiao-dan W (2006) Review of biological treatment of hypersaline wastewater. J Cent S Univ Technol 13:195–197Google Scholar
- Tovar A, Moreno C, Ma MP, Garciâa-vargas M (2000) Environmental impacts of intensive aquaculture in marine waters. Science 34:334–342Google Scholar