Analysis of Phosphate Removal using Ca(OH)₂ Modified Zeolite Based Adsorbents

Most of the wastewater treatment facilities are not well versed with phosphorus removal system. Adsorption is widely used as an advanced method for treatment of wastewater effluents with high as well as low phosphorus concentration. This study focuses on calcium hydroxide treated natural zeolite for the removal of phosphate in low concentration phosphorous streams. Different doses of calcium hydroxide (Ca(OH)₂) modified zeolite (CMZ) were examined for their efficiencies to remove phosphate from wastewater effluent from sewage treatment plant Hamirpur, Himachal Pradesh, India. The phosphate adsorption process was pH-independent that recommends favourable use of CMZ in conjunction with conventional treatment processes. Equilibrium condition was achieved after 5 days, thus suggesting the process to be time consuming; however fifty per cent of phosphate (PO₄^3-) was removed in first 6–12 hours, showing a sustainable process for removing intense phosphate polluted wastewater streams. Adsorption process was found to be endothermic in nature. Surface texture, mineralogy image were analysed using SEM. Adsorption kinetics and isotherms study was done by varying initial phosphate concentration. CMZ presents a promising sorbent for tertiary wastewater treatment.