Algae Grown on Dairy and Municipal Wastewater for Simultaneous Nutrient Removal and Lipid Production for Biofuel Feedstock

Abstract

Algae grown on wastewater media are a potential source of low-cost lipids for production of liquid biofuels. This study investigated lipid productivity and nutrient removal by green algae grown during treatment of dairy farm and municipal wastewaters supplemented with CO 2 .Dairy wastewater was treated outdoors in bench-scale batch cultures. The lipid content of the volatile solids peaked at Day 6, during exponential growth, and declined thereafter. Peak lipid content ranged from 14-29%, depending on wastewater concentration. Maximum lipid productivity also peaked at Day 6 of batch growth, with a volumetric productivity of 17 mg/day/L of reactor and an areal productivity of 2.8 g/m 2 /day, which would be equivalent to 11,000 L/ha/yr (1,200 gallons/acre/year) if sustained year-round. After 12 days, ammonium and orthophosphate removals were 96% and >99%, respectively. Municipal wastewater was treated in semi-continuous indoor cultures with 2-4 day hydraulic residence times (HRTs).Maximum lipid productivity for the municipal wastewater was 24 mg/day/L, observed in the 3-day HRT cultures. Over 99% removal of ammonium and orthophosphate was achieved.The results from both types of wastewater suggest that CO 2 -supplemented algae cultures can simultaneously remove dissolved nitrogen and phosphorus to low levels while generating a feedstock potentially useful for liquid biofuels production.1

Dairy Wastewater Treatment by Cyanobacteria for Removal of Nutrients with Extraction of High Value Compounds from Biomass

“…10% cyanobacterial cultures were used as an inoculum for growth in Erlenmeyer flask (500 ml) containing 250 ml of untreated and treated dairy wastewater. The culture was incubated at 27 o C ± 3 o C temperature for 18 days and measured physico-chemical analysis at interval of every 6 days (Woertz et al, 2005).…”

An Overview of Algae Biofuel Production and Potential Environmental Impact

“…Lipid production using dairy wastewater was populated by the algae genera Scenedesmus, Micractinium, Chlorella, and Actinastrum and demonstrated a maximum value of 17 mg L −1 day −1 . 117 Although this work is preliminary, the results indicate a fundamental positive correlation with nutrient removal and lipid production with the additional improvement of CO 2 uptake.…”

“…A benchtop study performed by Woertz et al 117 examined algae lipid productivity using municipal and agricultural wastewater. The municipal wastewater stream was populated by the algae genera Chlorella, Micractinium, and Actinastrum, and the lipid contents ranged from 9.7 mg L −1 day −1 (with the addition of air sparge and a 3-day hydraulic residence time [HRT]) to 24 mg L −1 day −1 (with the addition of CO 2 sparge and a 3-day HRT).…”

Lucrative future of microalgal biofuels in Pakistan: a review

“…For the production of liquid biofuels, wastewater media serve as a potential source of low-cost substrates [50]. The agro-industrial and municipal wastewaters appear cost effective and promising sustainable means for biofuel production through the cultivation of oleaginous microalgae [5].…”