Nutrient Removal Efficiencies of <i>Chlorella vulgaris</i> from Urban Wastewater for Reduced Eutrophication

Abstract

Urban wastewater contains both organic and inorganic nutrients and discharge of untreated water increases nitrogen and phosphorous content in water bodies leading to eutrophication problem. Physical and chemical treatment of urban waste water produces large quantities of waste sludge associated with secondary pollution. Microalgae can assimilate nutrients especially nitrogen and phosphorous from wastewater for their growth and produce valuable biomass and lipid. This study was performed to determine the growth of Chlorella vulgaris in urban wastewater (UWW) and Bold's basal medium (BBM) thereby identifying cost effective growth medium for microalga cultivation. In addition, nutrient removal abilities of C. vulgaris from various dilutions of urban waste water were explored at 10 days cultivation period. Specific growth rate, biomass and lipid content were higher in microalgae grown in urban waste water than BBM. The highest lipid productivity of 14.31 mg· L −1 ·day −1 was achieved in the culture grown in UWW medium which exceeded the BBM at 1.15 fold. The amount of nutrient removal tended to increase with higher dilutions of UWW. Removal rates of upto 87.9% and 98.4%were recorded for total nitrogen and total phosphorous by C. vulgaris. The results emphasized that urban waste water as a cost effective growth medium for higher biomass and lipid production accompanied with the nutrient removal efficiency of microalgae to reduce eutrophication.

TILAPIA CULTIVATED IN A LOW-SALINITY BIOFLOC SYSTEM SUPPLEMENTED WITH <i>Chlorella vulgaris</i> AND DIFFERENTS MOLASSES APPLICATION RATES

“…The low levels of orthophosphate compared with those found by Luo et al (2014) (~12.3 mg L -1 ) using the biofloc system, may be related to the abundance of the genera Chlorella (41-57% phytoplankton community) in all treatments. According to Ruiz et al (2011) and Singh et al (2017), C. vulgaris has a high potential for reducing the phosphorus of effluents.…”

“…About 60% of the nitrogen and 65% of the phosphorus that enter in the system are not converted into shrimp biomass (Silva et al, 2013). An alternative used to overcome the disadvantages is the use of microalgae in this system, due to their highly efficient removal of nitrogen and phosphorus (80-100%) in aquaculture, livestock and industry as have been reported by Prajapati et al (2014), Posadas et al (2015), Kuo et al (2016) and Singh et al (2017).…”

Applications of microalga Chlorella vulgaris in aquaculture

“…El-Kassas and Mohamed (2014) reported that the microalga is used in bioremediation of aquatic environment polluted with lead (Pb), cadmium (Cd), zinc (Zn), chromium (Cr) and mercury (Hg). Chlorella vulgaris is good at utilising the excess nutrients in aquatic environment thereby reducing the eutrophication level, as they have been reported to remove about 98.4% and 87.9% of total phosphorous and total nitrogen from polluted water (Sirakov et al 2015;Singh et al 2017). Chlorella spp.…”

Indoor and outdoor cultivation of Chlorella vulgaris and its application in wastewater treatment in a tropical city—Bangkok, Thailand

“…Among the outdoor PBRs, PBR3 displayed better algal density and growth rate than the PBR4. The growth difference between PBR1 and Singh et al [20] conducted an indoor experiment with 250-ml bottles. In their experiment, maximum algal density of C. vulgaris was 1.09 g/l and productivity was 0.17 g/l/d in controlled Bold's Basal medium, whereas with wastewater and no pH control, algal density was 1.13 g/l and productivity was 0.19 g/l/d.…”

“…Chlorella vulgaris did not grow in PBR2; however, energy consumption and cost of PBR2 have been discussed here. Some experiments were successfully conducted in indoor cultivation without pH control, e.g., experiment conducted by [20]. As microalgae in PBR1 required 10 days to reach maximum density, 10 days time period was considered for energy and cost analysis of both PBR1 and PBR2.…”