Phytoplankton as bioindicator for waste stabilization ponds

Waste stabilization ponds are an appropriate technology for domestic onsite wastewater treatment. It is a low-cost technology, requires low maintenance, is highly efficient, mostly natural and remarkablably sustainable. In facultative ponds, the existence of an algal population is very important for the stability of the symbiotic relation with aerobic bacteria. The aim of this work is to determine the pattern of microalgae in the facultative and maturation ponds to obtain information for the operation and maintenance work. The important parameters for phytoplankton measured in this study are the organic load, temperature, light penetration, dissolved oxygen and nutrients. Methodology consists in: analysis of main water quality parameters, plankton taxonomic determination and abundance calculation related with the maintenance operations. Results show that cyanobacteria are present in under-loaded conditions and chlorophyceae are present when the pond is overloaded. Using this methodology over time we can obtain a year round pattern to use the phytoplankton as a bioindicator of the pond’s conditions. Our conclusion is that the phytoplankton determination and density can be used to know the pond’s performance and help the operation and maintenance tasks.

► Cyanobacteria are present in under-loaded conditions.
► Concentrations of main nutrients, are highly reduced due to the biomass consumption.
► Faecal coliforms are dramatically reduced, due to the high pH and solar radiation.
► The main function of algae is producing oxygen to maintain the aerobic conditions.
► A relation can be established between water quality and phytoplankton development.