Conclusions

The present investigations on the treatment efficiencies of the STP showed moderate treatment levels with 60 % total COD removal, 50% of filterable COD removal; 82% of total BOD removal and 70% of filterable BOD removal. The nitrogen removal efficiency was lower. However, a rapid decrease in the suspended solids after a higher euglenoid growth indicates particulate carbon removal by algal ingestion. Euglenoides dominated the facultative pond and chlorophycean members were more abundant in the maturation ponds owing to variable surface BOD loadings. The transition in algal communities and biomass over the residence time was linked with shift from anaerobic to aerobic phase, with better organic matter removal. pH and DO were consistently correlated with higher algal abundance. Significant correlations between algal biomass and nutrients indicate the importance of the type and nature of algal communities that can be used as an efficient tool for predicting the dynamics of various phases in wastewater treatment systems. The bio-volume calculations for the standing population of the alga in the surface (20 cm) revealed  3.5 tons of algal dry weight accounting to 1.4 tons of immobilized carbon in algae, assumingthe doubling time of euglenoides was 1 week. The nutrient integrated efficiency showed a higher shortfall in treatment levels which might be in compliance to a provision of detention of a few days through an additional stabilization pondand anoptimal algal management in various phases.