title: Effect of illumination of nitrate and phosphate removal by coimmobilized Chlorella pyrenoidosa and activated sludge.
abstract: Chlorella pyrenoidosa and activated sludge were co-immobilized with simplifying modified PVA-sulfate method. Effects of light intensity and light:dark ratio on the growth of co-immobilized algae cells and removal of nitrate and phosphate were studied. The results indicate that the growth rate of co-immobilized algae cells reduces when light intensity is decreased from 4000 Lux to 1000 Lux, while optimal light:dark ratio for algal growth is 16:8. The influence of illumination on nitrate removal is so weak that the removal percentage can reach 90 approximately 100% within 12 approximately 24 h during the experimental periods in spite of changing illumination conditions. On the other hand, phosphate removal efficiency reduces when light intensity or light:dark ratio is decreased. The highest phosphate removal percentage is 99.6% under the circumstances of 4000 Lux and full-time illumination in our experiment, while the average phosphate removal is about 78%. The change of pH value in water samples is also observed. When water sample is treated by the co-immobilized system, pH value increases in light and decreases in dark. Microorganisms' physiological action is considered as the main mechanism that leads to the change of pH value.
authors.affiliation: College of Environmental Science & Engineering, Nankai University, Tianjin, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Wang
authors.forename: Guolan
authors.initials: G
authors.lastname: Huang
mesh_terms: D018914:Cells, Immobilized / Q000502:physiology; D002708:Chlorella / Q000254:growth & development*; D008029:Lighting; D009566:Nitrates / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D014865:Waste Disposal, Fluid / Q000379:methods; D018508:Water Purification / Q000379:methods
chemical_list: D009566:Nitrates; D010758:Phosphorus