Impact of microalgae layer thickness on the treatment performance of drain water.

The water shortage problem in Egypt has promoted the exploration of new water resources, including the use of treated agricultural drainage water. This study aims to develop an efficient and cost-effective method for the in-situ treatment of agricultural drainage water from the Bahr-ElBaqar drain using a microalgae layer. The objective was to establish the optimal thickness of the layer for achieving the highest removal efficiency of pollutants from the drain's wastewater. Practical work was performed on a pilot consisting of five channels with four channels having microalgae with different thicknesses and fixed lengths of 50 cm, and the fifth channel acting as a buffer channel to assimilate the drain water without any treatment microalgae layer. After the experiment, it was discovered that a 10-mm layer of microalgae was the most effective thickness for eliminating pollutants from wastewater. The removal efficiencies were 29% for biochemical oxygen demand (BOD), 46.9% for chemical oxygen demand (COD), and 56.1% for total suspended solids (TSS) removal. This experiment provided evidence that microalgae could represent a viable solution for in-situ treatment of agricultural drainage wastewater with high removal efficiencies for pollutants in wastewater and decreased the need for constructing huge and expensive wastewater treatment plants.