Adsorption photobioreactor as a co-treatment system for ammonium and phosphate removal by the response surface method

The co-treatment system of photosynthetic microalgae Chlorella vulgaris and adsorption was investigated as a possible combination of symbiotic mixed culture for the simultaneous removal of nutrients (ammonium and phosphate) and organic contaminants. In this study, response surface methodology for experimental design and optimization was used. For experiment operation, two factorial designs containing five chemical oxygen demand influent (COD_in) concentrations (100, 200, 400, 600 and 700 mg l^-1) and hydraulic retention times (0.63, 1, 1.75, 2.5 and 2.88 d) were applied. The co-treatment system performed successfully in removing both nutrients (nitrogen and phosphate) and COD, showing around 88%, 75% and 48% removal for the maximum level, respectively. The adsorption-photobioreactor (APBR) displayed superior performance of the microalgae growth rate compared to the photobioreactor. Also, the adsorption capacity (the uptake of COD) has been analysed with the first-order equation. The results showed that the experimental data of the APBR fit well with the model.