Integrated Haematococcus pluvialis biomass production and nutrient removal using bioethanol plant waste effluent

The integrated system of astaxanthin and microalgal biomass production, and wastewater treatment is a promising process. Haematococcus pluvialis is a suitable microalgae for this coupled system to achieve this dual purpose in a single approach. In this study, biomass production and nutrient removal from bioethanol plant wastewater by H. pluvialis were investigated. An air-lift photobioreactor was used to utilize the wastewater as well as a CO2-enriched gas supply. The maximum biomass density and maximum specific growth rate achieved were 4.37 +/- 0.007 g/L and 0.317 day(-1), respectively, by culturing H. pluvialis in an air-lift photobioreactor, supplemented with 5% CO2 in air. Removal of 91.7% total nitrogen and 100% total phosphorous from the wastewater was achieved. The residual microalgal biomass, obtained after astaxanthin extraction (1.109 +/- 0.009 mg/g DW), was characterized as a potential bioenergy feedstock due to its elevated higher heating value 15.6 +/- 0.01 MJ/kg. Hence, integrating H. pluvialis cultivation with bioethanol effluent serves the combined purpose of wastewater treatment, CO2 utilization, and simultaneous production of astaxanthin, which has a potential market value of over USD 2000 per kg, and carbohydrate rich microalgal biomass, which can be applied to bioenergy production. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.