Water Science and Technology最新文献

A Digital Twin built around Activated Sludge Model No. 1 was deployed at a full-scale water resource recovery facility. Its design included a waste rate recommender system based on automatic scenario analyses, where influent loads and waste rates are varied to determine their impact on nitrification. At the same frequency as these scenario analyses, scheduled auto-calibrations allow for nitrifier maximum specific growth rate (μ_max-NITO) soft sensing, the only kinetic parameter shown to require adjustment if the objective is aeration tank effluent ammonia forecasting accuracy. By integrating temperature forecasting over the next three sludge ages, this Digital Twin approach creates opportunities for advancing waste rate decisions in anticipation of seasonal temperature changes, optimizing ammonia control authority under varying influent loads, and furnishing valuable insights for future capital projects requiring nitrifier kinetic understanding and modelling.

A gravel contact oxidation system is an ecological engineering packed-bed reactor that uses gravel as a biofilm carrier to remove waterborne contaminants. While widely studied for pollution control, little is known about its microbial communities. In this study, we evaluated the system's effectiveness in reducing coliform bacteria, including antibiotic-resistant and hemolytic strains, as indicators of pollution and public health risk in Dongda Creek, Taiwan. Results showed a significant reduction in coliform levels, from 10⁵-10⁶ CFU/100 mL to 10² CFU/100 mL, along with notable improvements in water quality parameters like turbidity, total dissolved solids, and oxidation-reduction potential. Antibiotic-resistant coliforms were less prevalent in treated water, demonstrating the system's efficacy in control of bacterial flora that poses a risk to public health. Third-generation sequencing revealed reduced species richness in treated wastewater, while biofilm samples showed greater bacterial diversity. Gravel's surface area supported biofilm formation, promoting microbial communities capable of degrading organic pollutants. The activity of biofilm microbial community also decreased turbidity and dissolved solids, while shifting bacterial composition in the wastewater. These findings underscore the system's potential as a sustainable, effective model for ecological wastewater treatment.

The aim of this work is to investigate how open data can play a beneficial role in the regulation of combined sewer overflows (CSOs). The investigation consists of a review and critical discussion of historic CSO design, alongside more recent developments of regulations and emerging experiences of monitoring CSOs and different levels of data openness. The study focuses on practice in 10 European countries/regions. The novelty of this work comes from its review of historical development of design guidelines and regulations, shifts in the aims of these regulations, practicalities around implementation and testing of compliance, alongside the openness and availability of data. The main conclusions are that increasingly complex regulation goes hand in hand with limited compliance checking and opaque decision-making, whereas opening up relatively simplistic performance data has generated public and political discussion about urban drainage systems and the potential costs of improvements in water quality of the impacted surface water bodies. Making CSO data open does, however, need to be done with due care. Collaboration with trusted citizen groups, ensuring the data are correct, easy to access, and understand, as well as avoiding a blame culture are all of key importance.

Atmospheric deposition affects both aquatic and terrestrial ecosystems. In this study, the atmospheric deposition of nitrogen (N) and phosphorus (P) was investigated in Lake Kasumigaura, Japan's second-largest lake, for approximately seven years. Seasonal variations in the total N (TN) and total P (TP) fluxes tended to be higher in spring and lower from fall to winter. The annual variations could be categorized into three distinct periods in conjunction with the precipitation trend. The estimated annual fluxes based on these three periods showed that the TN flux was accurately predicted. A comparison of the results of this study with those of studies conducted around 1980 reveals that the concentration of dissolved inorganic N in wet deposition has declined. This suggests that decreased N oxide (NO_X) concentrations due to air pollution control measures contribute to the decrease in the nitrate (NO₃-N) flux in atmospheric deposition. Despite the reduction in N fluxes from atmospheric deposition, monthly calculations of the impact of atmospheric deposition on Lake Kasumigaura revealed that the total inflow load reached a maximum of 17% for TN and 26% for TP.

To address the issues of limited exploration capability and premature convergence in the optimization process of the Blood-Sucking Leech Optimizer (BSLO) algorithm, we propose an Improved BSLO (IBSLO) algorithm. Initially, a directional leeches switching mechanism based on an inverted S-shaped nonlinear perceived distance to strike a balance between exploitative and exploratory capabilities of the algorithm. Subsequently, a dynamic perception signal was designed to simulate dynamic stimulus signals, guiding leeches to search and optimize more accurately. Finally, the memory sharing mechanism is incorporated to improve search efficiency and secure the global optimal solution of the algorithm. In addition, the IBSLO algorithm is assessed through 23 benchmark functions and the standard test set from CEC-2017, with its superiority confirmed by a detailed analysis of the algorithm's convergence. To further assess the efficacy of the IBSLO algorithm in addressing practical optimization challenges, it was utilized to enhance the predictive model for crucial water quality parameters within the wastewater treatment procedure. The IBSLO-Deep Belief Network model's prediction results demonstrated superior accuracy compared with other optimization strategies, further confirming the excellent performance of the IBSLO algorithm.

Wastewater generated during toluene diisocyanate (TDI) production contains significant levels of nitrobenzenes (NBs), necessitating preliminary treatment to mitigate biotoxicity and improve biodegradability. Micro-electrolysis has been demonstrated to be an effective method for the degradation of NBs. Combined with Fenton oxidation and biochemical treatment, it has the potential to achieve stable compliance with wastewater standards during TDI production. This study evaluates micro-electrolysis and its synergistic effects with other treatment methods, based on both experimental and engineering practices. Experimental results revealed that micro-electrolysis degraded 48.57% of NBs at a pH of 3 and 0.1% of cast iron powder. Coupling micro-electrolysis with Fenton oxidation boosted degradation to 82.86%. The B/C ratio (B/C, defined as biological oxygen demand/chemical oxygen demand) improved from 0.047 to 0.252. In actual practice, micro-electrolysis reduced the effluent COD_cr (chemical oxygen demand with dichromate) of the subsequent Fenton oxidation unit by approximately 24.07%. Furthermore, under the synergistic effect of micro-electrolysis and Fenton oxidation, the effluent COD_cr from the hydrolysis-acidification process and the two-stage AO (anoxic-oxic) units were reduced by 28.41 and 15.27%, respectively. These results demonstrate its positive impact on subsequent treatment stages.

Digested sludge (DS) has a high organic content, and due to its large amounts to be disposed of, the post-thermal alkaline process (post-TAP) is investigated for DS disintegration, targeting to improve the organic solubilization for subsequent anaerobic digestion (AD) and reduce sludge volume. Seven DSs were treated at 160 °C for 30 min under pH 9-12 and then anaerobically digested. The maximum biogas yield of post-treated DSs reached 314-361 L/kg VS_added with TAP at pH 9, and the biogas production could be improved by 364-4,423 m³/d in the seven wastewater treatment plants (WWTPs) investigated. Besides, an additional electricity generation of 34% and a reduced sludge volume of 22% could be achieved in a model WWTP. Furthermore, in a model incineration plant with extended TAP and AD, the electricity balance of dewatered DS with 25% total solids (TS) was enhanced by 84.4 kWh/m³.

Pharmaceutically active compounds (PhACs) in wastewater pose significant environmental risks due to their persistence and potential to disrupt aquatic ecosystems. Onsite wastewater treatment systems (OWTS) often fail to adequately remove PhACs. This study investigated the efficiency of a multi-module biochar filter (MmBF) system as secondary treatment in OWTS for removing PhACs. Two parallel MmBF systems, each comprising six sequential modules filled with biochar, were evaluated for their removal of 25 detected PhACs across multiple pharmaceutical classes. The MmBFs were operated with municipal wastewater as influent for over one year, after which wastewater samples were collected and analysed from the influent and effluent of each module. The MmBFs showed consistent reduction in the aggregated PhACs concentrations by >99% over several sampling occasions, with only six PhACs having less than 95% removal. The first aerobic module M1 contributed to more than 92% of the total removal. The subsequent aerobic modules (M2-M3) provided additional reduction, resulting in over 98% of PhACs removal in the aerobic modules. In contrast, the anoxic modules (M4-M5) had a lower overall contribution, but the removal of specific compounds was observed, suggesting potential anaerobic degradation. This study demonstrates the potential of biochar-based systems as a sustainable option for OWTSs.

Global water scarcity drives the need for sustainable water management. Non-potable greywater (GW) reuse offers a viable strategy to reduce urban water demand. However, potential public health risks associated with exposure to pathogens in GW necessitate careful consideration. The World Health Organization (WHO) has established a benchmark of 1×10^-6 Disability-Adjusted Life Years (DALYs) per person per year (PPPY) for water-related health risks. This study develops and employs a stochastic Quantitative Microbial Risk Assessment (QMRA) model to evaluate the annual health risks associated with exposure to four bacterial pathogens in GW across eight exposure routes. Results indicate that exposure to raw GW presents an annual probability of illness of 1 × 10^-4 PPPY. Conversely, the use of treated GW significantly reduces the illness probability to 3.9 × 10^-5 PPPY, and the use of disinfected GW further decreases the risk to 7.1 × 10^-7 PPPY, an order of magnitude lower than the WHO's acceptable risk level. The findings indicate that the use of treated-and-disinfected GW, when managed with appropriate precautions, can maintain health risks within the tolerable limits defined by the WHO. This study provides a robust risk assessment framework that can inform the sustainable implementation of hybrid urban water systems.

The escalating impacts of global climate change and anthropogenic activities have exerted mounting pressures on urban aquatic ecosystems. This study employs Dongying City as a representative case study, where a comprehensive evaluation index system was constructed based on the Driving forces-Pressures-States-Impacts-Responses framework. The system incorporates 27 critical indicators, including population growth rate, gross domestic product (GDP) growth rate, and agricultural fertilizer application intensity, to assess aquatic ecosystem health status. The Technique for Order Preference by Similarity to Ideal Solution model was implemented to evaluate the ecological health status of Dongying City and its adjacent marine areas. Through obstacle factor analysis, key constraints impeding the sustainable development of regional aquatic ecosystems were identified, thereby establishing a theoretical foundation for ecological conservation and restoration initiatives. The findings demonstrate that the aquatic ecosystem's health status in Dongying City consistently attained intermediate or superior levels during the study period, exhibiting a progressive year-on-year improvement trend. Notably, the 'Impacts' subsystem has emerged as the predominant limiting factor for ecosystem health, superseding the previously dominant 'Pressures' subsystem. Multivariate analysis revealed six primary constraining factors: population growth rate, agricultural fertilizer application intensity, pesticide application intensity, macro- and mesozooplankton biomass, GDP growth rate, and phytoplankton density.