Microbial nutrient recovery cell as an efficient and sustainable nutrient recovery option in sewage treatment.

Globally, nutrient pollution is a serious and challenging concern. Wastewater treatment plants (WWTPs) are designed to prevent the discharge of contaminants resulting from anthropogenic sources to the receiving water bodies. In this study, seasonal nutrient pollution load, and biological nutrient removal efficiency of an anoxic aerobic unit based WWTP were investigated. Seasonal assessment revealed that the average total nitrogen removal efficiency and total phosphorus removal efficiency of the WWTP do not meet the discharge standard of 10 mg/L and 1 mg/L, respectively. Furthermore, the WWTP does not utilize the energy contained in the wastewater. In this regard, dual chamber MFC (D-MFC) has emerged as a promising solution that can not only treat wastewater but can also convert chemical energy present in the wastewater into electrical energy. However, higher N O3- (57 ± 4 mg/L) and P-P O43- (6 ± 0.52 mg/L) concentration in cathodic effluent is a major drawback in D-MFC. Therefore, to solve this issue, D-MFC was transformed into a microbial nutrient recovery cell (MNRC) which demonstrated a final N H4+-N and P-P O43- concentration of nearly 1 mg/L with N H4+-N and P-P O43- recovery up to 74 % and 69 %, respectively in the recovery chamber. Besides, MNRC attained a maximum power density of 307 mW/m3 and a current density of 1614 mA/m3, thus indicating MNRC is an eco-friendly, energy-neutral, and promising technology for electricity generation and recovering nutrients.

Life-cycle assessment approach for municipal solid waste management system of Delhi city.

The life-cycle assessment (LCA) approach with route optimization technique was adopted in the present study to evaluate environmental and economic aspects associated with the prevalent waste management system in Delhi city. With an objective of cost minimization and abating environmental hazards from waste transportation systems, ArcGIS was used to identify the most appropriate route for waste transportation. The study was conducted considering four landfills located at Bawana, Bhalswa, Ghazipur and Okhla present in Delhi city. Landfilling, composting, anaerobic digestion, and recycling methods were analyzed for global warming potential (GWP), eutrophication potential (EP), acidification potential, abiotic resource depletion potential and photochemical oxidation potential parameters using LCA software GaBiPro. The results from the LCA studies for the municipal solid waste management system of Delhi city revealed that transportation emissions and landfilling negatively impact the environment. The effect of recycling rate on the landfilling, composting, anaerobic digestion was also studied using sensitivity analysis. Results of sensitivity analysis depicted that recycling of waste is inversely related to the impact categories. Overall, the results exhibited a detrimental effect of landfilling on the environment in terms of GWP and EP. Further, considering the geospatial analysis, two waste recycling stations are proposed in the vicinity of existing waste management plants to reduce the time and cost of waste transport from the landfills to the waste management plants.

Examining current trends and future outlook of bio-electrochemical systems (BES) for nutrient conversion and recovery: an overview.

Nutrient-rich waste streams from domestic and industrial sources and the increasing application of synthetic fertilizers have resulted in a huge-scale influx of reactive nitrogen and phosphorus in the environment. The higher concentrations of these pollutants induce eutrophication and foster degradation of aquatic biodiversity. Besides, phosphorus being non-renewable resource is under the risk of rapid depletion. Hence, recovery and reuse of the phosphorus and nitrogen are necessary. Over the years, nutrient recovery, low-carbon energy, and sustainable bioremediation of wastewater have received significant interest. The conventional wastewater treatment technologies have higher energy demand and nutrient removal entails a major cost in the treatment process. For these issues, bio-electrochemical system (BES) has been considered as sustainable and environment friendly wastewater treatment technologies that utilize the energy contained in the wastewater so as to recovery nutrients and purify wastewater. Therefore, this article comprehensively focuses and critically analyzes the potential sources of nutrients, working mechanism of BES, and different nutrient recovery strategies to unlock the upscaling opportunities. Also, economic analysis was done to understand the technical feasibility and potential market value of recovered nutrients. Hence, this review article will be useful in establishing waste management policies and framework along with development of advanced configurations with major emphasis on nutrient recovery rather than removal from the waste stream.