A Sustainable Environmental Solution for Wastewater Treatment using Hapallosiphon sp. Alga

Microalgae-based wastewater treatment is a promising technology for advanced wastewater treatment and nutrient recovery, leveraging the ability of microalgae to remove carbon, nitrogen, and phosphorus from wastewater. In this study, the blue-green alga Hapalosiphon sp. was used to treat wastewater from the Hamdan plant, one of the largest treatment facilities in Basrah Governorate, southern Iraq. Three concentrations of wastewater (25%, 50%, and 75%) were prepared, and changes in pH were measured after cultivating the algae. By the end of the experiment, a decrease in the levels of pH was recorded with ranges from 9.41, 9.34, and 8.99 to 8.16, 8.32, and 8.04, respectively. While, the dissolved oxygen (DO) levels were recorded with a significant increase, from 6.2, 3.2, and 1.8mg/ L before treatment to 12.1, 6.4, and 6.5mg/ L at the end of the experiment for the 25, 50, and 75% concentrations, respectively. The main nutrients—carbon, nitrogen and phosphorus—were weekly measured throughout the experiment, with each measurement performed in duplicate. The removal percentages of these nutrients were calculated. The final carbon removal rates were 57, 34, and 26%, while nitrogen removal rates reached 100, 93, and 69.8% for the 25, 50, and 75% wastewater concentrations, respectively. Phosphorus removal showed a steady increase, from initial rates of 14.1, 46.2, and 48.2% at the end of the first week to 92.9, 93.7, and 85.2% by the third week. As a result of the treatment, the algal biomass increased significantly, rising from an initial 4g to 9.56g, 6.5g, and 5.02g for the 25, 50, and 75% wastewater concentrations, respectively.