Abstract During an attempt at the possible reclamation of solid waste from a chlor-alkali factory by blue-green algae, the effects of the solid waste on biochemical variables were studied. DNA, RNA, protein and algal nitrogen content of the algal material showed a significant decrease with increase in time and also solid waste concentration. An increase in RNA/DNA ratio and a decrease in protein/RNA ratio were also observed. Algae accumulated apprecoable amounts of mercury from the waste, showing dependence on both concentration and time. Significant correlations were obtained between mercury uptake and concentrations of the waste and between different combinations of algae and mercury uptake.