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Abstract
Excessive nitrogen and phosphorus discharge into natural water from wastewater treatment plants still have the potential of causing eutrophication. How to remove those excessive nitrogen and phosphorus in an appropriate way is welcome in practice. This study co-removed nitrate and phosphorus via the operation of commercial 201 × 7 exchange resin column, and recovered phosphate simultaneously. Experimental results demonstrated that the adsorption of -P onto the 201 × 7 resin satisfactorily fitted to Freundlich isotherm, while
-N followed Langmuir model, with a maximum adsorption capacity of 12.47 mg/g for
-P and 107.59 mg/g for
-N, respectively. Up to 92% of
-P and 90% of
-N in the secondary effluent were recovered by 201 × 7 resin column under the optimal flow rate of 50 BV/h. The exhausted 201 × 7 resin could be regenerated by 5% NaCl within 1 h at a flow rate of 15 BV/h. Moreover, this regeneration would guarantee the effluent
-P and
-N are lower than the breakthrough points even when 1175 BV wastewater passed the resin column. These findings are of great significance for ensuring stricter effluent phosphorus and total nitrogen discharge criteria.
Acknowledgment
The authors gratefully acknowledge the support by the Funds for Creative Research Groups of China (No. 51121062), and Project (HIT.NSIRF.2013111) Supported by Natural Scientific Research Innovation Foundation of Harbin Institute of Technology, as well as the China Postdoctoral Science Foundation funded projects (2013T60375 and 2012M520744).