Performance comparison between high-rate algal pond and conventional waste stabilization ponds for wastewater treatment at the University of Dar es Salaam, Tanzania

ABSTRACT

Comparison of HRAP and conventional waste stabilization ponds, highlighting treatment processes and removal efficiencies for organic matter, nitrogen, and faecal coliforms.

The High-Rate Algal Pond (HRAP) has become an increasingly preferred wastewater treatment technology over the conventional Waste Stabilization Pond (WSP). This study presents the results of the potential application of HRAPs for the treatment of domestic wastewater over conventional WSPs. The study was conducted to determine the treatment performance of HRAP through assessing wastewater parameters. Results show that HRAP removed more nutrients and faecal coliforms (FC) than WSPs. The removal efficiency for BOD5 was 44.48% in HRAP, whereas in WSPs, it ranged from 17.57 to 26%. Temperature, pH, Dissolved oxygen (DO), Electrical conductivity (EC), and Ammonia nitrogen (NH3–N) significantly influenced nitrification, with all parameters showing statistically significant effects (p < 0.05). The system reduced Org-N and NH3–N by 34.18 and 68.95%, respectively, while promoting nitrification, as evidenced by increased NO3–N concentrations. FC counts were reduced from 3.00 × 108 Cfu/100 ml in the influent to 1.45 × 108 Cfu/100 ml in WSP1, with a removal efficiency of 51.79%, while in HRAP, FC were reduced to 4.46 × 105 Cfu/100 ml with a removal efficiency of 99.85%. FC mortality was largely contributed to by pH 85%. Nitrogen and pathogen removal efficiency in HRAP implies better performance than conventional ponds.