Reduction in toxicity of wastewater from three wastewater treatment plants to alga (Scenedesmus obliquus) in northeast China

Abstract

The toxicity of municipal wastewater to the receiving water bodies is still unknown, due to the lack of regulated toxicity based index for wastewater discharge in China. Our study aims at gaining insight into the acute toxic effects of local municipal wastewater on alga, Scenedesmus obliquus. Four endpoints, i.e. cell density, chlorophyll-A concentration, superoxide dismutase (SOD) activity and cell membrane integrity, of alga were analyzed to characterize the acute toxicity effects of wastewater from municipal wastewater treatment plants (WWTPs) with different treatment techniques: sequencing batch reactor (SBR), Linpor and conventional activated sludge. Influent and effluent from each treatment stage in these three WWTPs were sampled and evaluated for their acute toxicity. Our results showed that all three techniques can completely affect the algal chlorophyll-A synthesis stimulation effects of influent; the algal cell growth stimulation effect was only completely removed by the secondary treatment process in conventional activated sludge technique; toxic effects on cell membrane integrity of two influents from WWTPs with SBR and conventional activated sludge techniques were completely removed; the acute toxicity on SOD activity was partially reduced in SBR and conventional activated sludge techniques while not significantly reduced by Linpor system. As to the disinfection unit, NaClO disinfection enhanced wastewater toxicity dramatically while UV radiation had no remarkable influence on wastewater toxicity. Our results illustrated that SOD activity and chlorophyll-A synthesis were relatively sensitive to municipal wastewater toxicity. Our results would aid to understand the acute toxicity of municipal wastewater, as well as the toxicity removal by currently utilized treatment techniques in China.

The Integration of Bioanalytical Approaches in the Assessment of Municipal Wastewater Treatment Plant Performances

“…In this study, poor correlations obtained between chronic toxicity using P. subcapitata and some physicochemical parameters may indicate that the growth inhibition as an endpoint is not sensitive enough to detect these relationships. These findings are confirmed in a recent study of Zhang et al [48]. In fact, the chlorophyll-A synthesis of Scenedesmus obliquus appears more sensitive than biomass and showed significant positive correlations with the concentrations of TP (r = 0.793, p = 0.004) and total organic carbon TOC (r = 0.727, p = 0.011), NH 3 -N (r = 0.555, p = 0.077) and COD (r = 0.545, p = 0.083) [48].…”

Seasonal Variation in Ability of Wastewater Treatment for Reduction in Biological Effects Evaluated Based on Algal Growth

“…The biological effects of wastewater on algae have been evaluated in some locations overseas, which have reported that some wastewater has had biologically harmful effects on algae, and that wastewater treatment decreased these effects [1][2][3][4]. In Japan, the Ministry of the Environment has considered the introduction of the Whole Effluent Toxicity test [5] (named J-WET in this paper) for the management of chemicals in wastewater.…”

Health Effects Associated with Wastewater Treatment, Reuse, and Disposal

“…Surujlal-Naicker et al (2015) studied the toxicity of estrogenic hormones and the removal of toxicity in full-scale WWTPs using the marine bacterium, Vibrio fischeri to determine ifthere was a correlation between the hormones and the toxicity in the effluents. The results of this study revealed that the toxicity of the influent could be reduced to a certain extent in the biological treatment and that the residual estrogen contents as well as the toxicity could be reduced in certain WWTPs as well Zhang, Sun et al (2015). reported that the acute toxicity to Scenedesmus obliquus could be reduced in municipal WWTPs in northeast China.…”