Hydraulic head effect on the removal of nutrients in a chlorophyte algae photobioreactor at continuous and batch flows, in a percolation filter effluent

Abstract

The present article evaluates the effect that the hydraulic load produces, on the total nitrogen and total phosphorus removal in a photobioreactor (FB) installed in the wastewater treatment plant of the University of San Carlos of Guatemala. The FB was fed by the source of the percolating filter of stage III and exposed to solar radiation during the months of March to May, period of which growths of algae of the Chlorella type are reported. Three photobioreactors were built, those that worked at hydraulic loads: low (FBHB), medium (FBHM), high (FBHA), to conditions of continuous flow and batch. The hydraulic loads evaluated were 1.32, 3.23, 5.32 m3/m2/ day. The maximum growth of algae of the Chlorella type was obtained on the seventh day reaching a value of 3.2x10⁶ cel/mL in the FBHM, in the FBHB a value of 2.4x10⁶ cel/mL and in the FBHA a value of 2.56x10⁶ cel/mL. The average concentration of total nitrogen at the entrance of the FB working at continuous flow was 71.67 mg/L; at the output of the FBHB 65.67 mg/L; at the output of the FBHM, 63.00 mg/L; in the FBHA of 60.67 mg/L. The removal efficiency of 8.37 %, 12.09 %, and 15.35 % respectively. The behavior of the photobioreactor working at batch flow showed similar efficiencies, being 17.65 % for the FBHB, 15.09 % for the FBHM, and 18.67 % for the FBHA. In the case of total phosphorus, the concentration of entry into the FB working at a continuous flow was 14.77 mg/L; at the outputs of the FBHB of 8.27 mg/L; for the FBHM of 5.00 mg/L; for the FBHA of 5.57 mg/L. With removal efficiencies of 44.02 %, 66.14 % and 62.30 % respectively. The concentration of phosphorus at the entrance of the FB working with batch flow was 12.87 mg/L, at the outputs of the FBHB was 13.87 mg/L, for the FBHM of 11.18 mg/L; for the FBHA of 10.15 mg/L, with removal efficiencies of -7.77 %, 13.08 % and 21.11 % respectively.