How effective is microalgae treatment of nursery wastewater for nutrient removal?

Abstract

Nutrient removal from wastewaters has been traditionally achieved by activated sludge. But, in recent years, microalgae have been exploited for nutrient removal from wastewaters with the aim of producing fatty acid for use as biofuel. There are studies available on algae production using piggery, dairy and municipal wastewater, however, the rates of nutrient removal and algal growth have not been fully investigated. Furthermore, the growth rates of algae in different wastewaters for potential lipid production have not been fully established. Hence, in this paper, it was aimed to investigate the nutrient removal and algal growth using wastewater collected from a leafy vegetable nursery. Experiments were conducted using a batch reactor, having a capacity of 3.5 L. The reactor was filled with the nursery wastewater and inoculated by Chlorella vulgaris microalgae. Both compressed air and CO2 were supplied to provide the inorganic carbon necessary for the algal growth. The required illumination for growth was provided by florescence light. Algal growth was monitored by measuring the volatile solid concentration and cell density using spectrophotometer. Algae were harvested soon after the peak growth for future fatty acid measurement. In this paper, the experimental results on nutrient removal, algae growth in nursery wastewater along with online measurements including pH and dissolved oxygen dynamics during the culturing period are discussed.