Wastewater Treatment for Industrial Estates in Southeast Asia Using Water Hyacinths

Abstract

Pilot scale experiments were conducted to examine the applicability of water hyacinth systems for the treatment of raw wastewater discharged by small factories and housing areas of an industrial estate. Results obtained are encouraging, and justify the idea of starting wastewater treatment in the early phase of an estate's development with aquatic plant treatment systems which later can be further employed for advanced treatment. Although sludge accumulated extensively in the inlet zone of the plug-flow system, and oxygen was deficient in the bulk of the liquid, BOD and COD dropped to a level satisfying secondary treatment standards. Nitrogen was eliminated to a great extent suggesting that nitrification was occurring, presumably at the root surface, and denitrification in the outer oxygen deficient zones. Batch experiments demonstrated that the plants were able to satisfy the oxygen demand of both heterotrophic bacteria and nitrifiers forming the root supported biofilm.