Wastewater treatment and algal productivity in an integrated ponding system

A pilot plant was constructed to investigate the use of integrated ponding systems for municipal wastewater treatment in arid regions. The main objectives of this study were to determine the wastewater treatment efficiency of this system and to investigate the algal productivity under various operational and environmental conditions.

Treatment efficiency was determined in the facultative and high-rate ponds which were operated in series at various water depths, organic loadings and detention times. Control ponds with fixed parameters were also operated. The results showed the efficiency of this system in removing organic content of the municipal wastewater. Removals of up to 95% BOD, 85% COD, 90% ammonia and >99% of the pathogenic indicator microorganisms were achieved. Equations relating to algae productivity. Secchi disk measurements, suspended solids measurements and algae counts were developed. Algae productivities of 150–300 kg ha⁻¹ day⁻¹ were obtained under favorable conditions. Generally, high productivities were obtained at low detention times and greater pond depths in high-rate ponds, and at high organic loading within the ranges investigated.