Analysis of the Water Quality Characteristics of Urban Streams Using the Flow–Pollutant Loading Relationship and a Load Duration Curve (LDC)

For urban streams, wastewater inflow makes water quality management difficult. This study attempted to analyze the water quality characteristics and pollution sources for the efficient management of water quality in the upper, middle, and lower Gul-po stream reaches. The water quality and flow characteristics for each point were analyzed using five-year water quality and flow discharge data at Gul-po stream from 2016 to 2020. The results showed that the flow increased and the water quality improved in the upper part of the stream, under the influence of a treated water discharge. The flow–pollutant loading equation revealed that the flow coefficient (slope of the regression equation) values of the water quality characteristics, except T-N, were lower than 1 in the upper part, indicating that the water quality decreased as the flow increased. In the middle and lower parts, the flow index values of the water quality characteristics, except T-N, were greater than 1, indicating that the water quality increased with the flow. For the middle and lower parts, the overage rate of target water quality by the Ministry of Environment was high for high-flow discharge sections, indicating the significant influence of nonpoint pollution sources. These results show that it is necessary to consider different pollution sources at each point for urban stream quality management.

Developing a Multicriteria Decision Analysis Framework to Evaluate Reclaimed Wastewater Use for Agricultural Irrigation: The Case Study of Maryland

Groundwater is the main source of irrigation and residential use in the Eastern Shore Maryland, which is experiencing challenges regarding overuse, saltwater intrusion, and diminishing productivity. The Chesapeake Bay is also facing the problem of water pollution due to pollutant loading from agricultural fields and wastewater treatment plants (WWTPs). Using recycled water for irrigation has the potential to alleviate the pressure on groundwater and reduce pollutant loading. The objective of this study was to develop a decision tool to explore the use of recycled water for agricultural irrigation in Maryland using Multicriteria Decision Analysis (MCDA) integrated with Geographical Information Systems (GIS). Four main evaluation criteria were included in the GIS-MCDA framework: agricultural land cover, climate, groundwater vulnerability, and characteristics of the WWTPs as sources of recycled water. Groundwater vulnerability zones were developed using the groundwater well density, water extraction data, and the aquifer information. Then, the most suitable areas for irrigation using recycled water were identified. About 13.5% and 32.9% of agricultural land was, respectively, found to be “highly” and “moderately” suitable for irrigation with recycled water when WWTPs were categorized based on their treatment process information. The results provide a useful decision tool to promote the use of recycled water for agricultural irrigation.

Installation of a bioelectrochemical system as a pre-cleaner in a constructed wetland with higher pollutant loading under continuous mode

In this study, two-phase continuous vertical flow constructed wetlands were installed with a pre-cleaner bioelectrochemical system for the removal of NH4+-N (60.41–85.78%), NO3−-N (25.55–35.18%), TN (57.80–84.65%), TKN (37.24–70.08%), PO43−-P (38.89–63.40%), SO42− (49.53–76.06%), and COD (25.83–74.70%) from municipal wastewater.