The impact of printing industry effluent on the growth and antioxidant response of the freshwater green microalga Chlorella sorokiniana

Abstract

Contamination of aquatic ecosystems with printing industry wastewater is a serious concern because of the toxicity associated with the  effluent components and a tendency to create cascading ecological effects. The influence of printing-press effluent on the freshwater  microalga Chlorella sorokiniana strain UTEX2714 was studied under controlled laboratory conditions. The microalga was subjected to  various effluent concentrations prepared by diluting printingpress effluent with bold basal medium (BBM) in the following ratios  (effluent:medium): 1:149, 1:119, 1:99, 5:95 and 10:90, reflecting greater concentrations of the effluent. The control BBM had no effluent  added. Higher effluent concentrations had a negative impact on the cell density of C. sorokiniana; at low effluent concentrations the algae  displayed a high growth rate and high chlorophyll a production (p < 0.05), although total chlorophyll content did not differ  significantly among treatments (p ≥ 0.05). This study also discovered an increase in peroxidase activity in this microalga in response to  higher concentrations of printing-press effluent, which indicated an increase in oxidative stress that prompted antioxidant defence  mechanisms. We conclude that printing-press effluent adversely affects the physiology of C. sorokiniana, indicating the potential of  printing wastewater to harm phytoplankton in freshwater environments.