Abstract
A laboratory experiment was performed to determine the feasibility of coupling a conventional wastewater treatment system with an algal photobioreactor (PBR) for the removal of nutrients from wastewater and production of renewable resources. An activated sludge batch reactor was set up in series with an algal PBR to feed synthetic wastewater to Chlorella vulgaris. The nutrient concentration in the water as well as lipid content, carbohydrate content, and growth rate of the algal biomass were tested over 10 cycles to determine the capabilities of the coupled system. The study revealed complete nutrient removal in some cycles, with the average final nutrient content of 2 mg-P/L and 3 mg-N/L in effluent of the PBR. The algae biomass contained 24% ± 3% lipids and 26% ± 7% carbohydrates by dry weight. A life cycle assessment revealed the highest energy demand occurred during harvesting of the algal mixture through centrifugation or filtration, but the highest global warming and eutrophication impacts were due to CO2 use and PBR construction material production. It is feasible for the system to treat wastewater while generating renewable resources, but the system must be optimized to reduce life cycle environmental impacts and result in a net energy gain before large-scale implementation is possible.
Highlights
To meet growing clean water and energy demands, the concept of industrial symbiosis may be applied to a water and energy paradigm in which a wastewater treatment system is coupled with an algal photobioreactor (PBR)
It is estimated that the addition of nitrification to an activated sludge wastewater treatment plant results in an increase of 60% - 80% of the energy consumed at the plant [5], and evidence suggests that nitrous oxide emissions increase when biological nutrient removal is added to a wastewater treatment plants (WWTPs) [6]
Water going into the conventional bioreactor (CBR) was a synthetic wastewater feed with controlled nutrient levels comparable to influent at a wastewater treatment plant
Summary
To meet growing clean water and energy demands, the concept of industrial symbiosis may be applied to a water and energy paradigm in which a wastewater treatment system is coupled with an algal photobioreactor (PBR). The current solution to improving water quality through nutrient removal is to invest more energy and resources into wastewater treatment plants (WWTPs) [1,2]. The nutrient concentration of wastewater can be reduced to low levels, but the advantages of advanced treatment are often offset by the additional consumption of energy and resources [1,2]. It is estimated that the addition of nitrification to an activated sludge wastewater treatment plant results in an increase of 60% - 80% of the energy consumed at the plant [5], and evidence suggests that nitrous oxide emissions increase when biological nutrient removal is added to a WWTP [6]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
