Discharge of nutrient rich wastewater causes eutrophication of surface water; therefore wastewater treatment before discharge is required. Wastewater stabilization ponds are low cost technology used by developing countries but not effective in nitrogen removal due to low nitrifier biomass in the water column. Introduction of surface area for attach

1. Introduction  2 The effect of baffles on algal-bacterial biofilm structure and composition of zooplankton  3 Comparison of hydraulic flow patterns  4 Nitrification in bulk water and biofilms  5 Nitrification rates of algal-bacterial biofilms  6 Effect of operational conditions on the nitrogen removal  7 Nitrogen mass balances for pilot scale biofilm stabilization ponds under tropical conditions