Phosphate adsorption performance of a novel filter substrate made from drinking water treatment residuals
Wendong Wang
,
Cui Ma
,
Yinting Zhang
,
Shengjiong Yang
,
Yue Shao
,
Xiaochang Wang
DOI:10.1016/j.jes.2016.01.010
Received December 04, 2015,Revised January 20, 2016, Accepted January 26, 2016, Available online February 26, 2016
Volume 28,2016,Pages 191-199
Phosphate is one of the most predominant pollutants in natural waters. Laboratory experiments were conducted to investigate the phosphate adsorption performance of a (NFS) made from drinking water treatment residuals. The adsorption of phosphate on the NFS fitted well with the Freundlich isotherm and pseudo second-order kinetic models. At pH 7.0, the maximum adsorption capacity of 1.03 mg/g was achieved at 15°C corresponding to the wastewater temperature in cold months, and increased notably to 1.31 mg/g at 35°C. Under both acidic conditions (part of the adsorption sites was consumed) and basic conditions (negative charges formed on the surface of NFS, which led to a static repulsion of PO43 − and HPO42 −), the adsorption of phosphate was slightly inhibited. Further study showed that part of the adsorption sites could be recovered by 0.25 mol/L NaOH. The activation energy was calculated to be above 8.0 kJ/mol, indicating that the adsorption of phosphate on NFS was probably a chemical process. Considering the strong phosphate adsorption capacity and recoverability, NFS showed great promise on enhancing phosphate removal from the secondary treated wastewater in the filtration process.
