Ecological Risk Assessment Of White Mud Desulfurization Wastewater Discharging Into The Sea

White mud desulfurization wastewater is the wastewater using seawater andwhite mud for flue gas desulfurization. The main ingredients (Mg2+, Ca2+, SO42-, COD,suspended solids and heavy metal) of white mud desulfurization wastewater areanalyzed. According to a scientific review on domestic and international research, thestudy about the impacts of white mud desulfurization wastewater on the marineenvironment focusses on the impacts of water quality indices such as COD and heavymetals. Scientists are less engaged in research into the impacts of white muddesulfurization wastewater on the halation’s physiological function, such as algae andseashell and biological community structure. So this article mainly determines thetoxicity effect of white mud desulfurization wastewater on marine organisms by labtoxicity tests and evaluates the influence on marine environment after white muddesulfurization wastewater discharging into the sea.The Skeletonema costatum and Platymonas subcordiformis was exposed to whitemud desulfurization wastewater at various concentrations. After a period of time ofexposure, the growth rate, chlorophyll a, photosynthetic rate and respiration rate oftwo microalgal species, Skeletonema costatum and Platymonas subcordiformis, weremeasured. The experimental results show that desulfurization wastewater have nosignificant impact on the growth rate and chlorophyll a of algae, and have little impacton the photosynthesis and respiration rate. When the wastewater is diluted between20%and40%, there is a slight promotion on photosynthesis and respiration, whichshows that the algae show a certain stress response.The Ruditapes philipinarium and Chlamys farreri was also exposed to the whitemud desulfurization wastewater at various concentrations. After a period of time ofexposure, the death rate and the activities of SOD and CAT were measured. Theexperimental results show that desulfurization wastewater have no significant impacton Ruditapes philipinarium and Chlamys farreri. The activities of SOD and CAT in low concentration (3%-50%) were increased slightly, but the activities of SOD andCAT were decreased when the white mud desulfurization wastewater’s concentrationwas increased.This paper also investigated the biological community structure around the areainto whcih the white mud desulfurization wastewater was discharged. The surveyitems included chlorophyll a, phytoplankton, zooplankton and benthic community.The results show that the diversity index was lower, and the area around thewastewater outlet has been polluted to some extent. Compared with that obtained in2006, the diversity index didn’t have decreased tendency, but individual indicatorswere better. This contrast shows that the ecological quality has no obvious change.