Techno-economic characteristics of wastewater treatment plants retrofitted from the conventional activated sludge process to the membrane bioreactor process

• Retrofitting from CAS to MBR increased effluent quality and environmental benefits. • Retrofitting from CAS to MBR increased energy consumption but not operating cost. • Retrofitting from CAS to MBR increased the net profit and cost efficiency. • The advantage of MBR is related to the adopted effluent standard. • The techno-economy of MBR improves with stricter effluent standards. While a growing number of wastewater treatment plants (WWTPs) are being retrofitted from the conventional activated sludge (CAS) process to the membrane bioreactor (MBR) process, the debate on the techno-economy of MBR vs. CAS has continued and calls for a thorough assessment based on techno-economic valuation. In this study, we analyzed the operating data of 20 large-scale WWTPs (capacity≥10000 m³/d) and compared their techno-economy before and after the retrofitting from CAS to MBR. Through cost-benefit analysis, we evaluated the net profit by subtracting the operating cost from the environmental benefit (estimated by the shadow price of pollutant removal and water reclamation). After the retrofitting, the removal rate of pollutants increased (e.g., from 89.0% to 93.3% on average for NH₃-N), the average energy consumption increased from 0.40 to 0.57 kWh/m³, but the operating cost did not increase significantly. The average marginal environmental benefit increased remarkably (from 0.47 to 0.66 CNY/g for NH₃-N removal), leading to an increase in the average net profit from 19.4 to 24.4 CNY/m³. We further scored the technical efficiencies via data envelopment analysis based on non-radial directional distance functions. After the retrofitting, the relative cost efficiency increased from 0.70 to 0.73 (the theoretical maximum is 1), while the relative energy efficiency did not change significantly. The techno-economy is closely related to the effluent standard adopted, particularly when truncating the extra benefit of pollutant removal beyond the standard in economic modeling. The modeling results suggested that MBR is more profitable than CAS given stricter effluent standards.     

Occurrence,distribution, sources,and bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in multi environmental media in estuaries and the coast of the Beibu Gulf,China: a health risk assessment through seafood consumption

Environmental Science and Pollution Research - The coastal zone is a crucial transitional area between land and ocean, which is facing enormous pressure due to global climate change and...     

Agricultural non-point sources and their effects on chlorophyll-a in a eutrophic lake over three decades (1985–2020)

Environmental Science and Pollution Research - Erhai Lake is the second largest freshwater lake in Yunnan Province but suffers from the deterioration of water quality and agricultural non-point...     

Systematic review and meta-analysis of studies between short-term exposure to ambient carbon monoxide and non-accidental,cardiovascular, and respiratory mortality in China

Environmental Science and Pollution Research - Although a growing number of original epidemiological studies imply a link between ambient pollution exposure and mortality risk, the findings...     

Numerical modeling of changes in groundwater storage and nitrate load in the unconfined aquifer near a river receiving reclaimed water

Environmental Science and Pollution Research - Reclaimed water (RW) has been widely used as an alternative water resource to recharge rivers in mega-city Beijing. At the same time, the RW also...     

Synergistic effects of gaseous pollutants on hospital admissions for cardiovascular disease in Liuzhou,China

Previous studies demonstrated that short-term exposure to gaseous pollutants (nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and ozone (O₃)) had a greater adverse effect on cardiovascular disease. However, little evidence exists regarding the synergy between gaseous pollutants and cardiovascular disease (CVD). Therefore, we aimed to estimate the effect of individual gaseous pollutants on hospital admissions for CVD and to explore the possible synergistic effects between gaseous pollutants. Daily hospitalization counts for CVD were collected from January 1, 2014, to December 31, 2015. We also collected daily time series on gaseous pollutants from the Environment of the People’s Republic of China, including NO₂, SO₂, and O₃. We used distributed lag nonlinear models (DLNMs) to assess the association of individual gaseous pollutants on CVD hospitalization, after controlling for seasonality, day of the week, public holidays, and weather variables. Then, we explored the variability across age and sex groups. In addition, we analyzed the synergistic effects between gaseous pollutants on CVD. Extremely low NO₂ and SO₂ increase the risk of CVD in all subgroup at lag 7 days. The greatest effect of high concentration of SO₂ was observed in male and the elderly (≥ 65 years) at lag 3 days. Greater effects of high concentration of O₃ were more pronounced in the young (< 65 years) and female at lag 3 days, while the effect of low concentration of O₃ was greater in male and the young (< 65 years) at lag 0 day. We found a synergistic effect between NO₂ and SO₂ for CVD, as well as between SO₂ and O₃. The synergistic effects of NO₂ and SO₂ on CVD were stronger in the elderly (≥ 65) and female. The female was sensitive to synergistic effects of SO₂-O₃ and NO₂-O₃. Interestingly, we found that there was a risk of CVD in the susceptible population even for gaseous pollutant concentrations below the National Environmental Quality Standard. The synergy between NO₂ and SO₂ was significantly associated with cardiovascular disease hospitalization in the elderly (≥ 65). This study provides evidence for the synergistic effect of gaseous pollutants on hospital admissions for cardiovascular disease.

     

Novel visible-light-driven SrCoO3/Ag3PO4 heterojunction with enhanced photocatalytic performance for tetracycline degradation

Environmental Science and Pollution Research - The semiconductor photocatalytic technology has been considerably studied due to its excellent catalytic performance in water pollution control....     

Inactivation of E. coli and Streptococcus agalactiae by UV/persulfate during marine aquaculture disinfection

Environmental Science and Pollution Research - Sulfate radical (?SO4?)–based advanced oxidation processes have attracted a great deal of attention for use in water disinfection...     

How does turions production of Potamogeton crispus L. respond to parental population biomass and living environment

Environmental Science and Pollution Research - Turions production is the dominant means of propagation in Potamogeton crispus L. To understand how parental population and their living environmental...     

Near-surface wind profile test based on accuracy verification of UAV anemometer lifting height in an urban fringe built-up area

Environmental Science and Pollution Research - Multirotor UAVs (unmanned aerial vehicles) have been widely used in urban vertical wind environment testing, whereas less attention has been given to...