Total Nitrogen Reduction Research Articles

Circular economy approach for wastewater treatment farming in Bangpakong River basin

Bangpakong River is one of river basins that faced the pollution problem in Thailand. This river is located in the downstream of central pain of Thailand and flows into the sea at the gulf of Thailand. Water quality problems in the last decade of this river basin are appeared from the low water quality index with evidences such as dead of fish, black color of water, low Dissolved Oxygen (DO) concentrations, high organics and nutrients concentrations, high contaminated of coliform bacteria. All wastewater is controlled by the environmental law. Only wastewater from agriculture part is not yet properly managed. The objective of this study was to quantify the mass and material flows in agricultural farms such as pig, fish and prawn farms. Circular economy concept as reuse of wastewater in agricultural farms was approached in scenario. Surveys, questionnaires and water samplings were taken for farms. Information and mass flows within the farms were analyzed. This study found that the main source of pollution from these farms mostly resulted from the effluent of wastewater in term of Biological Oxygen Demand (BOD) and Total Nitrogen (TN) loads, were discharged into the environment. The hot spot areas were canals which flow to the river. Mass flows in pig farm revealed that BOD and TN loads to the environment were 90, and 120 tons/year. In which, calculated thresholds were 30 and 60 tons/year for BOD and TN. Similar results also found from aquaculture farms which contributes BOD and TN loads of 187 and 77 tons/year for fish farms and 156 and 84 tons for prawn farms. In this study, calculated reuse as circular economy approach about 50% of farm wastewater to agricultural field could provide the key role of BOD and TN reduction to the environment, and meeting the threshold level.

Treatment of high-load organic wastewater by novel basalt fiber carrier media

The carrier medium plays a key role in improving existing remediation potential of conventional biological contact oxidation reactors. In this study, a biological contact oxidation reactor was constructed using basalt fiber (R-BF) as a biological carrier. The bioreactor performance was investigated in terms of reduction in chemical oxygen demand (COD), ammonium nitrogen (NH4+-N), and total nitrogen (TN) at organic loadings rate of 15.243 kg/m3·d and nitrogen loading rate of 1.068 kg/m3·d. We found that COD, NH4+-N, and TN were reduced to 99.1%, 97.9%, and 97.8%, respectively. Within the R-BF, a bio-nest was developed which had abundant pores and channels and supported successful movement of nutrients, resulting in high biological activity (55.78%). The microbial communities within the bio-nest were diverse and rich and sludge production during operation was minimal. This makes BF a promising application for wastewater treatment. This research might be useful in the construction of integrated bioreactors that can operate under high organic and nitrogen loadings rates with reduced energy consumption, i.e. 75% in this study.

Effect of an Olive Vegetation Water Phenolic Extract on the Physico-Chemical, Microbiological and Sensory Traits of Shrimp (Parapenaeus longirostris) during the Shelf-Life.

The aim of this study was to evaluate the effects of phenolic extract derived from olive vegetation water (PEOVW) in deep-water rose shrimps (Parapenaeus longirostris) at the day of packaging (D0) and after three (D3), six (D6) and eight (D8) days of refrigerated storage. Freshly caught shrimps were randomly divided into four groups: the phenolic extract (PE) group (2 g/L of phenols); the sulfites (S) group (0.5% sodium metabisulfite solution); the phenolic extract + sulfites (PE + S) group (0.25% sodium metabisulfite solution with 1 g/L of phenols), and the control (CTRL) group (tap water). Concerning color coordinates, there were no variations either between groups or over time, while it is important to highlight that phenolic extract (PE group) led to a significant reduction in total volatile basic nitrogen (TVB-N; p < 0.001) and thiobarbituric reactive substances (TBARS; p < 0.001) values. Furthermore, PE also had a relevant effect in reducing bacterial counts and decreasing the microbial development. Finally, as concerns melanosis, the effect of phenolic extract alone was marginal, but when combined with half a dose of sodium metabisulfite, it was as effective as the shrimps treated with only sodium metabisulfite in delaying black spots (p < 0.05). These results are very promising with a view to commercializing additive-free shrimps.

Hybrid constructed wetlands as post-treatment of blackwater: An assessment of the removal of antibiotics

New sanitation systems have been developed to treat, recover energy and nutrients, and permit reuse processes at the source of generation, minimizing water use and flow segregation. Thus, this study was carried out with the objective of evaluating the potential of hybrid constructed wetlands in the removal of organic matter, nutrients, pathogenic microorganisms, and 12 antibiotics from blackwater previously treated by an upflow anaerobic sludge blanket reactor. A hybrid system of constructed wetlands was used, comprised of a horizontal subsurface flow constructed wetland with a total volume of 0.60 m3 followed by a vertical subsurface flow constructed wetland with a total volume of 0.20 m3. Three different hydraulic retention times were comparatively tested (1.0, 2.0, and 3.0 days for the horizontal subsurface flow constructed wetland, and 1.1, 0.9, and 0.4 days for the vertical subsurface flow constructed wetland) in four distinct stages. The plant species used was Canna x generalis. The results from this study demonstrate the potential of constructed wetlands as a suitable technology for post-treatment of segregated domestic wastewater (anaerobically-digested blackwater). Efficient reduction of COD, BOD5, total nitrogen, and total phosphorus (74, 93, 50, and 61%, respectively) was achieved, with a hydraulic retention time of 3.0 and 1.1 days for horizontal and vertical subsurface flow constructed wetland, respectively (stage IV). The presence of ciprofloxacin was confirmed by chromatographic and mass spectrometric analysis in an average concentration of 442.6 ng.L−1 at the inflow of the horizontal subsurface flow constructed wetland, but was not observed at the outflow.

Quality improvement of pangasius fillets using aqueous seaweed (Padina tetrastromatica) extract

Meat discoloration and fat oxidation are the major quality issues in pangasius fillet during storage. In this study, aqueous seaweed extracts prepared from Padina tetrastromatica using three protocols were evaluated based on its total phenolic content and antioxidant activities. Based on the ideal result, different concentration of seaweed extracts ranging from 0.5 to 2% (v/v) were used for dipping the pangasius fillet. Individual fillet samples were packed stored under chilled condition (2 °C). Among the quality parameters proximate composition, total volatile basic nitrogen, free fatty acids, thiobarbituric acid reactant substances, myoglobin content, aerobic plate count, instrumental colour and sensory analysis were carried out at regular intervals of 4 days. Seaweed extract containing phenolics reduced the myoglobin oxidation which is positively correlated with redness values. Among the different treatments 2% aqueous extract showed reduction in total volatile basic nitrogen, rancidity, total bacterial count, sensory quality parameters and effectively reduced the spoilage and meat discoloration of fillet up to 20 days. It can be concluded that aqueous seaweed extract can be used as a natural additive for improving meat colour and extending the storage life of fishery products under chilled conditions.

Impact Assessment of Best Management Practices (BMPs) on the Water Footprint of Agricultural Productions

Agriculture is the main source of diffuse nutrient pollution in surface waters. It requires best management practices (BMPs) for controlling the discharges of pollutants like total nitrogen (TN) and total phosphorous (TP). In addition, these pollutants are accounted in the grey water footprint (GWF) of agricultural productions. This study proposes an integrated methodology with two steps for assessing the impacts of BMPs on the water footprints (WF) of agricultural productions. First, this approach uses the soil and water assessment tool (SWAT) for basin modeling and calculating the required data for WF assessment. In the second step, the WFs of agricultural productions are quantified and compared in different BMP scenarios, including fertilizer and irrigation reduction (FIR) and the application of vegetated filter strips (VFS). The SWAT modeling shows that FIR and VFS are more effective on TN and TP reduction, respectively. It can estimate that the combination of BMPs has the potential of abating 60% of the TN and TP concentrations of lake in 8 years. However, the WFs of agricultural productions may not be significantly reduced by BMPs as the average GWF only constitutes 4.2% of WF in this basin. For instance, the combination of FIR and VFS can reduce the average WF of cereals from 44 to 41 m3/km2. Nevertheless, this practice is relatively more effective for irrigated crops. The WF of rain-fed crops remains constant on 37 m3/km2, while it is reduced 24% (from 91 to 69 m3/km2) for irrigated crops by BMPs. In addition, it is realized that FIR can adversely reduce the production yields up to 32%. All these findings verify that the proposed methodology can integrate BMP and WF assessments by SWAT modeling and is recommended for basins, where farmlands are the dominated land-use.

Denitrification in urban river sediment and the contribution to total nitrogen reduction

Streams and rivers, especially in urban areas, are substantial sinks of bioavailable nitrogen owing to their hydrological connections with terrestrial systems and the intensity of inputs mediated by human activities. Denitrification can account for nitrogen removal in rivers, but its importance in urban rivers has been scarcely studied. This study chose 8 representative rivers in Shanghai, under different level of urbanization, and measured denitrification rates of sediments across a year. The results showed significant differences in temporal, spatial and vertical distributions (p < 0.05). Seasonally, the denitrification rate in spring and winter were lower than in autumn. Spatially, the higher denitrification rate of rivers in residential and industrial areas than that in suburban rivers, which dominated with cultivated land, was weakly related to dissolved oxygen (DO) (p < 0.05, r = −0.380) and ammonium nitrogen (NH4+-N) concentration (p < 0.05, r = 0.303) in the water column. Vertically, the surface layer (0–2 cm) accounted for 78.2% of the total denitrification capacity (0–5 cm). The denitrification rates among different depths positively correlated with the extractable nitrate concentration (SNO3−-N), the extractable ammonium nitrogen concentration (SNH4+-N), the organic carbon concentration (SOC), water content and pH of sediment to varying degrees. In addition, the mean annual denitrification rate of studied rivers was calculated as 2.62 ± 0.420 mg N m−2 h−1, and denitrification contributed nearly 20% of the nitrogen removal, these results underscore the importance of denitrification in nitrogen reduction of urban rivers.

Effects of grape and pomegranate waste extracts on poultry carcasses microbial, chemical, and sensory attributes in slaughterhouse.

Contamination of poultry carcasses is considered as a critical point in the evaluation of poultry meat safety. The present study aimed at determining the decontamination effects of natural antimicrobial derived from grape waste extract and pomegranate waste extract (GWE and PWE) on poultry carcasses in a slaughterhouse. Poultry carcasses were treated in chiller with concentrations of 0, 2, 4 and 6% of pomegranate and grape waste extracts. Pomegranate and grape waste extracts contained 432.20 and 328.43 mg GAE/g total phenolic compounds. These extracts showed significant antimicrobial effect on the main poultry bacteria in vitro. On the first day of cold storage, significant reduction in total bacterial counts (p < .05) was observed in treated carcasses. After 3 days of storage time, total bacteria, Staphylococcus aureus, and Escherichia coli reduced significantly (p < .05) compared to untreated samples. At sixth and ninth days of storage time, significant reduction in total volatile nitrogen (TVN), total bacteria counts, Staphylococcus aureus, coliforms, and Escherichia coli were observed. Sensory attributes in treated carcasses with PWE and GWE have been enhanced significantly compared to untreated during acceptable shelf time (p < .05). Based on the results, pomegranate and grape waste extracts can be used to preserve and improve the shelf life of the poultry carcasses close to the standard range until the ninth day of storage. Application of pomegranate and grape waste extracts in slaughterhouse could be considered as an environmentally, natural and safe decontamination intervention in integral food safety system.

Water quality trends under rapid agricultural expansion and enhanced in-stream interception in a hilly watershed of Eastern China

Conflicts between agricultural intensification and the increasing demand for clean water resources are growing worldwide. This study sought to understand how the negative consequences of agricultural expansion in fragile hilly watersheds can be mitigated by ecologically based engineering practices. We analyzed long-term and seasonal water quality trends in two sub-watersheds of the Tianmu Lake watershed in Eastern China. The Zhongtian and nearby Zhucao sub-watersheds are very similar in terms of climate, topography and other features that can influence water quality. Both are experiencing rapid expansion of tea plantations, but the Zhongtian River contains an engineered system of overflow dams and cascade wetlands that is absent from the Zhucao River. The multi-year averaged reduction (2009–2018) of total nitrogen (TN) and total phosphorus (TP) from upstream to downstream reaches was 10%–15% greater in the engineered Zhongtian River compared to the non-engineered and free flowing Zhucao River, which has no interventions to reduce nutrient concentrations. Average annual reductions in TN, TP, and total suspended solids (SS) downstream of the engineered system reached 0.5%–4.0% of their multi-year averaged concentrations over this time interval. These reductions occurred despite a 2.3-fold expansion of tea plantation area in the engineered watershed, which contrasts with deteriorating water quality in the non-engineered watershed that had a 0.4-fold expansion of tea plantation area. Our results underscore the value of such engineered systems to improve water quality and help reconcile competing advantages of agricultural development and environmental protection in hilly watersheds, where there is limited in-stream processing of nutrients and the effects of human activities are substantial.

Design and development of a portable and streamlined nutrient film technique (NFT) aquaponic system

One pilot-scale portable Nutrient Film Technique (NFT) aquaponic system has been designed, developed, and tested at ICAR-CIFA, Bhubaneswar for a period of 90 days (October to December 2018) to study the efficiency of the new design. The experimental setup has three separate units, each consisting of four major components, such as Fibreglass Reinforced Plastic (FRP) round fish culture tank (ø2.15 × 0.9 m) with operational capacity 2800 L, biofilter unit made up of Polypropylene (PP) of 100 L capacity, FRP rectangular hydroponics tank (4 × 0.9 × 0.35 m) having 2.64 m2 plantation area and High-density Polyethylene (HDPE) sump (ø0.6 × 0.7 m) of 200 L capacity. Implementation of custom designed and calibrated automatic water recirculation system gives an average flow rate of 94.7 L/h for continuous flow of nutrients from fish culture tank to hydroponics tank. The designed system harnesses gravity flow in 75 % of the cycle. For performance assessment, the system was initially stocked with 54 numbers of fish fry/m3 (153.7 g/m3) of pangas (Pangasius hypophthalmus) in culture tank and 27 marigold (Tagetes erecta) plants/m2 in hydroponics tank. Length and weight gain of fish were by 77.04 % and 397.2 % from initial, respectively, and marigold plant harvested 107 number of flowers/m2. The Total Ammoniacal Nitrogen (TAN) reduction in biofilter was found to be 61.97 %.

Ecosystem-scale nutrient cycling responses to increasing air temperatures vary with lake trophic state

Understanding potential effects of climate warming on biogeochemical cycling in freshwater ecosystems is of pressing importance. Specifically, increasing air and water temperatures could accelerate nutrient cycling in lakes, which has major implications for in-lake nutrient concentrations, water column nutrient stoichiometry, and downstream nutrient export. Lakes may respond differentially to warming based on their current trophic state, although direct comparisons of temperature-driven changes in nutrient cycling between low- and high-nutrient lakes are lacking. Here, we used an open-source coupled hydrodynamic biogeochemical model to simulate ecosystem-scale changes in water column total nitrogen (TN) and total phosphorus (TP) concentrations and TN:TP ratios due to potential incremental changes in air temperature (from +0 °C to +6 °C) in a low-nutrient and a high-nutrient lake. Warming resulted in lower TN and higher TP epilimnetic (surface water) concentrations in both lakes, resulting in reduced molar TN:TP ratios in both lakes. While the high- and low-nutrient lakes had similar magnitude reductions in TN:TP ratio between the +0 °C and +6 °C scenarios (30.3% and 34.6%, respectively), median epilimnetic TN:TP in the low-nutrient lake significantly decreased with as little as 1 °C of warming. Warming also altered net nutrient retention, with decreased downstream export of TN but increased downstream export of TP in both lakes. Our modeling results suggest that low-nutrient lakes may respond to warming at lower levels of temperature increase than high-nutrient lakes, and that climate warming could intensify effects of nutrient enrichment driven by increased N and P loading due to land-use change.

Non-biological methods for phosphorus and nitrogen removal from wastewater: A gap analysis ofreinvented-toilet technologies with respect to ISO 30500.

The aims of the Reinvent the Toilet Challenge (RTTC) include creation of an off-the-grid sanitation system with operating costs of less than US$0.05 per user per day. Because of the small scale at which many reinvented toilets (RT) are intended to operate, non-biological treatment has been generally favored. The RTTC has already instigated notable technological advances in non-sewered sanitation systems (NSSS). However, increasingly stringent liquid effluent standards for N and P could limit the deployment of current RT in real-world scenarios, despite the urgent need for these systems. The newly adopted ISO 30500 standards for water reuse in NSSS dictate minimal use of chemical/biological additives, while at the same time requiring a 70% and 80% reduction in total nitrogen and phosphorus, respectively. This document provides a brief overview of the mature and emerging technologies for N and P (specifically ammonia/ammonium and orthophosphate) removal from wastewater. At present, the dearth of nutrient removal methods proven to be effective at small scales is a significant barrier to meeting ISO 30500 standards. Closing the gap between RTs and ISO 30500 will require significant investments in basic R&D of emerging technologies for non-biological N and P remediation and/or increased reliance on biological processes. Adaptation of existing nutrient-removal technologies to small-scale NSSS is a viable option that merits additional investigation.

Full-scale N removal from centrate using a sidestream process with a mainstream carbon source.

An innovative approach to treat centrate for rapid nitrogen load discharge reduction was investigated and applied at the Truckee Meadows Water Reclamation Facility (TMWRF) in Reno, NV. This process allowed TMWRF to circumvent an anticipated exceedance of the individual waste load allocation in 2018. Existing infrastructure and equipment were re-purposed in a full-scale suspended growth biological centrate treatment system, attaining simultaneous nitrification, and denitrification with no additional capital investment. Functioning within a few days of start-up, the average ammonia reduction was 81% (1,106kg/day) and the average total nitrogen reduction in the sidestream was 53% (757kg/day) using primary effluent as carbon source. Alkalinity and carbon limitations were both anticipated and observed; however, adaptive operations allowed for balancing of nitrification and denitrification processes, providing pH stability and success in meeting treatment goals. Immediately after the sidestream treatment system was placed into service, nitrogen in the mainstream facility was measured at concentrations significantly lower than typical and was sustained at historically low concentrations throughout the operation. This translated into a significant methanol cost savings of $1,500 per day (USD). The system has become a critical supplemental treatment process during upcoming rehabilitation projects to address aging infrastructure of existing nitrogen treatment facilities. PRACTITIONER POINTS: Full scale demonstration of sidestream N removal using a hybrid process. Integration of the sidestream N process to reduce N effluent load without alkalinity or supplementary carbon augmentation. Operational solution to reduce operating costs without new infrastructure.

Effect of pre-treatment of wastewater in HRAP on nitrogen removal in subsurface flow gravel bed constructed wetland

This study discusses the effect of application of High Rate Algal Pond (HRAP) as a pre-treatment unit on nitrogen transformation and removal in Sub-surface flow Gravel bed Constructed Wetland (SGCW). Experiments were carried out at the University of Dar es Salaam main campus wastewater treatment facility in two different settings. In Phase I, effluent from primary facultative pond was fed directly to unplanted gravel bed SGCW, with a discharge of 0.69 m3/d. During Phase II, the HRAP with 0.6 m depth, received effluent from primary facultative pond at a flow rate of 1.2 m3/d and discharged it to unplanted gravel bed SGCW with 0.8 m deep, filled to 10 cm above water level with 20 mm diameter aggregates, at a flow rate of 0.69 m3/d. Both HRAP and SGCW were operated at a retention time of 5 days. The results showed that improved nitrogen removal occurred with inclusion of HRAP unit. In Phase I, an average nitrogen removal of 41.3% was achieved, while in Phase II total nitrogen reduction in SGCW improved to 57.3%. These results show the significance of HRAP for better performance of nitrogen removal in gravel bed SGCW. It was further observed that the removal efficiency of nitrate-nitrogen was superior in SGCW phase II (68.2%) compared to SGCW phase I (20.7%). Hence this research proved that provided the influent is fully nitrified in the pre-treatment system such as HRAP, denitrification becomes the major contributor to the nitrogen removal process in SGCW.

Responses of a semi-natural grassland community of tropical region to elevated ozone: An assessment of soil dynamics and biomass accumulation

Despite knowing the phytotoxic effects of tropospheric ozone (O3), which is of global concern, there is no study so far reported about its impacts on grassland community of tropical regions. Therefore, we assessed the responses of a semi-natural grassland community of Indo-Gangetic plains to elevated O3 exposure (Ambient + 20 ppb) compared to ambient after three years of exposure using open-top chambers. Percent decreases were found in above (26%; p ≤ 0.002) and belowground (30%; p ≤ 0.003) biomass under elevated compared to ambient O3 exposure. Percent decrements in total organic carbon (TOC; 24%; p ≤ 0.001), total nitrogen (29%; p ≤ 0.001) and available phosphorus (11%; p ≤ 0.002) in the soil were also observed under elevated O3 exposure. Exposure at elevated O3 reduced soil microbial biomass and activities of β-glucosidase, amylase, urease and phosphatase, while polyphenol oxidase and peroxidase showed enhancement in their activities, showing negative effects on belowground soil health. Percent reduction in root shoot ratio (10%; p ≤ 0.05) depicts that less C-allocation towards root system led to a reduction in TOC in the soil, which could affect C-sequestration under elevated O3 condition in the semi-natural grasslands. Elevated O3 also affected enzymes participating in N and P-cycles, causing reductions in total nitrogen and phosphorus. The study concludes that projected O3 concentrations have serious implications for aboveground biomass as well as belowground soil health in tropical areas, identified as hotspots of O3 in the world.

Non-Point Source Pollution Simulation and Best Management Practices Analysis Based on Control Units in Northern China.

Non-point source (NPS) pollution simulation in control units can identify critical pollution source areas and make Best Management Practices (BMPs) more effective for the responsible parties. In this study, the control unit division method is introduced, and the spatial and temporal distribution characteristics of NPS pollution in the Guishui River Basin of Northern China are analyzed using the Soil Water Assessment Tool (SWAT) model. In addition, five BMP scenarios were designed for environmental and cost-benefit analyses. The results show that the loss of total nitrogen (TN) and total phosphorus (TP) is concentrated in the rainy season, and the loss of TN and TP is mainly distributed in the middle and lower reaches of the main stream of the Guishui River. This area accounts for 22.34% of the basin area. The vegetated filter strips (VFS) scenario had the best environmental benefits with average TN and TP reduction efficiencies of 63.4% and 62.6%, respectively. The Grassed Waterway was the most cost-effective scenario measure, cost-benefit (CE) values of TN and TP were 1798.13 g/€ and 601.56 g/€. Generally, research on NPS pollution using control units can more clearly identify the critical source areas of pollution than other methods, and provides technical support for watershed management decision makers.

Field testing of a household-scale onsite blackwater treatment system in Coimbatore, India

4.2 billion people live without access to safely managed sanitation services. This report describes the field testing of an onsite prototype system designed to treat blackwater from a single flush toilet and reuse of the treated effluent for flushing. The system passes wastewater through a solid-liquid separator followed by settling tanks and granular activated carbon columns into an electrochemical reactor that oxidizes chloride salts from urine to generate chlorine to remove pathogens. The objectives of the study were to verify the functionality of the system (previously demonstrated in the laboratory) under realistic use conditions, to identify maintenance requirements, and to make a preliminary assessment of the system's user acceptability. The prototype was installed in a women's workplace and residential toilet block in Coimbatore, India, and tested over a period of 10 months. The treated water met stringent disinfection threshold for both E. coli and helminth eggs and produced a clear, colorless effluent that met or nearly met local and international discharge standards for non-sewered sanitation systems. The effluent had an average chemical oxygen demand of 81 mg/L, total suspended solids of 11 mg/L, and reduction of total nitrogen by 65%. These tests determined the recommended service lifetimes and maintenance intervals for key system components including the electrochemical cell, granular activated carbon columns, and solid-liquid separator. User feedback regarding the use of treated blackwater as flush water was positive. These findings will inform the design and implementation of next-generation systems currently under development.

Evaluating watershed-based optimized decision support framework for conservation practice placement in Plum Creek Minnesota

Targeting field-scale implementation of conservation practices (CPs) in agricultural watersheds is critical to meeting sustainable resource management goals. This not only needs accurate and extensive field-scale assessment, but also incorporation of willingness of the farmers to adopt the suite of practices. Many useful watershed models have not only lacked in accurate siting of field-scale practices based on rigorous physiographic/terrain criteria and hydro-conditioned digital elevation models (DEMs), but also limited in mathematically incorporating farmer’s uncertain, diverse and conflicting viewpoints into the model, which is pivotal to TMDL scenario assessment. This study develops an integrated decision support framework (DSF) to site CP opportunities at the field-scale using high-resolution Light Detection and Ranging (LiDAR)-hydro-conditioned DEM and other secondary data. Using python coding, DSF integrates three robust models namely Prioritize, Target and Measure Application (PTMApp), Agricultural Conservation Planning Framework (ACPF) and Hydrological Simulation Program FORTRAN-Scenario Application Manager (HSPF-SAM). The novel nature of this framework is its ability to facilitate precision planning at field-scale by siting the optimized conservation practices to achieve TMDL’s based on (i) rigorous terrain derivatives and siting criteria; (ii) simulation of accurate stream flow network (extensive hydro-conditioning and D infinity approach for flow accumulation); and (iii) incorporating diverse, conflicting and uncertain preferences of farmers using fuzzy logic. The framework offers a simplified interface to the locals to simultaneously address agronomical (siting practices to improve soil health and crop productivity), hydrological (improving water quality, TMDL’s), ecological (delineation of sites for riparian buffers) and socio-economic (farmer preferences and cost-analysis) objectives with moderate technical expertise. Besides field-scale practice siting, one of the superior features of the model is its flexibility to filter out even technically feasible cost-effective practices if they are not preferred by farmers, and thus giving a realistic assessment of TMDL’s. The model is applicable to any Hydrologic Unit Code (HUC-12) sub-watershed and has been demonstrated for Plum Creek watershed in Minnesota. Results showed 537 cost-effective practices including bioreactors, grassed waterways, nutrient removal wetlands, water and sediment control basins and riparian buffers yielded an 8.5% reduction in total nitrogen constrained with a budget of $250,000. Field-scale maps generated through this DSF empowers practitioners and farmers to work together to make implementation decisions based on sound agronomic, water quality, and economic considerations.

Water quality performance of a permeable pavement and stormwater harvesting treatment train stormwater control measure

Abstract Stormwater runoff from urban development causes undesired impacts to surface waters, including discharge of pollutants, erosion, and loss of habitat. A treatment train consisting of permeable interlocking concrete pavement and underground stormwater harvesting was monitored to quantify water quality improvements. The permeable pavement provided primary treatment and the cistern contributed to final polishing of total suspended solids (TSS) and turbidity concentrations (&amp;gt;96%) and loads (99.5% for TSS). Because of this, &amp;gt;40% reduction of sediment-bound nutrient forms and total nitrogen was observed. Nitrate reduction (&amp;gt;70%) appeared to be related to an anaerobic zone in water stored in the scarified soil beneath the permeable pavement, allowing denitrification to occur. Sequestration of copper, lead, and zinc occurred during the first 5 months of monitoring, with leaching observed during the second half of the monitoring period. This was potentially caused by a decrease in pH within the cistern or residual chloride from deicing salt causing de-sorption of metals from accumulated sediment. Pollutant loading followed the same trends as pollutant concentrations, with load reduction improved vis-à-vis concentrations because of the 27% runoff reduction provided by the treatment train. This study has shown that permeable pavement can serve as an effective pretreatment for stormwater harvesting schemes.

Water Quality Responses during the Continuous Mixing Process and Informed Management of a Stratified Drinking Water Reservoir

Aeration and mixing have been proven as effective in situ water quality improvement methods, particularly for deep drinking water reservoirs. While there is some research on the mechanism of water quality improvement during artificial mixing, the changes to water quality and the microbial community during the subsequent continuous mixing process is little understood. In this study, we investigate the mechanism of water quality improvement during the continuous mixing process in a drinking water reservoir. During this period, we found a reduction in total nitrogen (TN), total phosphorus (TP), ammonium-nitrogen (NH4-N), iron (Fe), manganese (Mn), and total organic carbon (TOC) of 12.5%–30.8%. We also measured reductions of 8.6% and 6.2% in TN and organic carbon (OC), respectively, in surface sediment. Microbial metabolic activity, abundance, and carbon source utilization were also improved. Redundancy analysis indicated that temperature and dissolved oxygen (DO) were key factors affecting changes in the microbial community. With intervention, the water temperature during continuous mixing was 15 °C, and the mixing temperature in the reservoir increased by 5 °C compared with natural mixing. Our research shows that integrating and optimizing the artificial and continuous mixing processes influences energy savings. This research provides a theoretical basis for further advancing treatment optimizations for a drinking water supply.