Suspended Solids Loads Research Articles

A multi-objective optimization and evaluation framework for LID facilities considering urban surface runoff and shallow groundwater regulation

Currently, the goals of sponge city construction mostly focus on urban surface water, with few considerations of groundwater indicators, and there is a lack of simulation methods that consider the interaction between surface water and groundwater under low impact development (LID) scenarios. Taking a sponge campus in Xi'an as the research object, this paper proposes a method to realize the interaction between surface water and groundwater at different spatial and temporal scales, so as to construct a SWMM-MODFLOW coupled numerical model to carry out the analysis of hydrological effect of sponge city comprehensively taking into account both surface water and groundwater. Simultaneously, the SWMM is coupled with the NSGA-III algorithm for multi-objective optimization of LID facility configurations, aiming to identify a globally optimal solution set for LID facility configurations under both long and short-duration rainfall scenarios. A novel framework for a comprehensive evaluation system of surface water-groundwater benefits is also developed to comprehensively assess LID facility optimization schemes that meet the goals of stormwater runoff infiltration and reduction, pollution interception and purification, and groundwater recharge conservation. The simulation results show that after optimization, the LID scheme has good surface runoff regulation effects and pollution reduction capabilities, reducing the runoff peak from 2.297 m3/s to 2.128 m3/s, significantly lowering the risk of inundation and effectively reducing the total suspended solids (SS) load by 42.38 kg at the outfall. Meanwhile, the groundwater recharge effect is particularly significant in September. Compared to the baseline scenario, the average groundwater levels from June to September were raised by 3.966 cm, 5.120 cm, 6.743 cm, and 7.639 cm, respectively. The maximum daily groundwater level rise reached 7.82 cm, while the average groundwater level for the whole year of 2023 increased by 2.61 cm. The maximum transport area of pollutants decreased from 2359.44 m2 to 1796.54 m2, and the maximum transport distance reduced from 79.985 m to 69.977 m. Additionally, the central concentration of pollutants also decreased. This optimization evaluation framework will aid decision-makers in selecting LID facility management strategies that balance the dual benefits of surface water runoff and groundwater regulation.

Biomonitoring emerging hazards of pharmaceuticals in river water using gut microbiome and behavioural Daphnia magna responses

A cost-effective Daphnia magna testing framework was applied to identify emerging hazards such as neurological and cardiovascular defects as well as antibiotic resistant genes (ARGs), related to pharmaceuticals present in waste water treated (WWTP) effluent discharged into rivers. D. magna juveniles were exposed during 48 h to water samples from three rivers in the vicinity of Barcelona (NE Spain), Besós, Llobregat and Onyar, upstream and downstream of WWTP discharging points. The analyses included measuring levels of 80 pharmaceutical residues in water samples by HPLC-MS, determination of the loads of different clinically relevant antibiotic resistant genes (ARGs) in both water samples and exposed animals, and assessment of toxic effects in feeding, heartbeat responses, and behavioural indicators. ARG prevalence in water, but not in gut microbiomes, was associated with the presence of bactericides in water. These results suggest that their levels were high enough to put a selective pressure over river microbial populations, but that Daphnia guts were not easily populated by environmental bacteria. Toxic effects were found in 20 to 43% of water samples, depending on the river, and related to water quality parameters and to pollutant levels. For example, heartbeats were correlated with salinity, whereas feeding impairment did so with high loads of suspended solids. In contrast, behavioural alterations were associated to the concentration of neuroactive chemicals. Accordingly, we hypothesize that measured neuroactive chemicals have caused the observed effects. If this also applies to local invertebrate populations, the environmental consequences may be severe and unpredictable.

Linking global terrestrial and ocean biogeochemistry with process-based, coupled freshwater algae–nutrient–solid dynamics in LM3-FANSY v1.0

Abstract. Estimating global river solids, nitrogen (N), and phosphorus (P), in both quantity and composition, is necessary for understanding the development and persistence of many harmful algal blooms, hypoxic events, and other water quality issues in inland and coastal waters. This requires a comprehensive freshwater model that can resolve intertwined algae, solid, and nutrient dynamics, yet previous global watershed models have limited mechanistic resolution of instream biogeochemical processes. Here we develop the global, spatially explicit, and process-based Freshwater Algae, Nutrient, and Solid cycling and Yields (FANSY) model and incorporate it within the Land Model (LM3). The resulting model, LM3-FANSY v1.0, is intended as a baseline for eventual linking of global terrestrial and ocean biogeochemistry in next-generation Earth system models to project global changes that may challenge empirical approaches. LM3-FANSY explicitly resolves interactions between algae, N, P, and solid dynamics in rivers and lakes at 1° spatial and 30 min temporal resolution. Simulated suspended solids (SS), N, and P in multiple forms (particulate or dissolved, organic or inorganic) agree well with measurement-based yield (kg km−2 yr−1), load (kt yr−1), and concentration (mg L−1) estimates across a globally distributed set of large rivers, with an accuracy comparable to other global nutrient and SS models. Furthermore, simulated global river loads of SS, N, and P in different forms to the coastal ocean are consistent with published ranges, though regional biases are apparent. River N loads are estimated to contain approximately equal contributions by dissolved inorganic N (41 %) and dissolved organic N (39 %), with a lesser contribution by particulate organic N (20 %). For river P load estimates, particulate P, which includes both organic and sorbed inorganic forms, is the most abundant form (64 %), followed by dissolved inorganic and organic P (25 % and 11 %). Time series analysis of river solid and nutrient loads in large US rivers for the period ∼ 1963–2000 demonstrates that simulated SS and N loads in different N forms covary with variations of measurement-based loads. LM3-FANSY, however, has less capability to capture interannual variability of P loads, likely due to the lack of terrestrial P dynamics in LM3. Analyses of the model results and sensitivity to components, parameters, and inputs suggest that fluxes from terrestrial litter and soils, wastewater, and weathering are the most critical inputs to the fidelity of simulated river nutrient loads for observation-based estimates. Sensitivity analyses further demonstrate a critical role of algal dynamics in controlling the ratios of inorganic and organic nutrient forms in freshwaters. While the simulations are able to capture significant cross-watershed contrasts at a global scale, disagreement for individual rivers can be substantial. This limitation is shared by other global river models and could be ameliorated through further refinements in nutrient sources, freshwater model dynamics, and observations. Current targets for future LM3-FANSY development include the additions of terrestrial P dynamics, freshwater carbon, alkalinity, enhanced sediment dynamics, and anthropogenic hydraulic controls.

Assessing flood-depth effects on water quality, nutrient uptake, carbon sequestration, and rice yield cultivated on Histosols

In the Everglades Agricultural Area (EAA), Florida, cultivating rice in flooded paddies is becoming increasingly popular to conserve water and soil health. Flood depth is a critical factor affecting the discharged water quality, soil carbon, and yield production. However, few studies have comprehensively investigated the optimal flood depth in EAA, considering multi-functional indices. To address this gap, we investigated drainage water quality, water quantity, nutrient uptake, soil carbon, and rice yield in rice paddies in histosol soils over a two-year period at four flood depths (5, 10, 15, and 20 ​cm). For each flood depth, averaged over two years, total outflow loadings of suspended solids, nitrogen, phosphorus, and potassium were significantly reduced by 40 ​%, 38 ​%, 36 ​%, and 32 ​%, respectively, compared to inflow water loadings (p ​< ​0.001). Soil organic carbon (SOC) in 5, 10, 15, and 20 ​cm flood treatments increased annually at a rate of 3.85 ​%, 5.64 ​%, 6.86 ​%, and 6.86 ​%, respectively; for these same treatments, soil active organic carbon (AOC) decreased annually at rates of 11.75 ​%, 8.63 ​%, 20.07 ​%, and 8.48 ​%, and rice grain yield was 4488, 5103, 5450, and 5386 ​kg ​ha−1, respectively. Overall, considering the water quality, SOC, AOC, and rice yield production, irrigating rice paddies at a flood depth of 15 ​cm most effectively improves water quality, increases carbon sequestration, reduces active carbon, and yields more rice than other flood depths. By evaluating the effects of flood depth on the soil–water–plant nexus in a holistic manner, we propose a more sustainable and environmentally friendly mode of rice cultivation within the EAA.

Total suspended solid (TSS) pollution load model at the Jagir River Estuary, Surabaya, East Java

The research aims to create a TSS spatial distribution map model and a pollution load model at the Jagir River Estuary—a descriptive method for the last six years to describe the TSS pollution load model. Satellite image data processing uses SNAP software with the application of the Laili algorithm (2015). The distribution of TSS pollution values and loads still meets the quality standards for mangrove ecosystems. The average value of TSS distribution in 2018 - 2023, respectively, is 18,966 mg/L, 14,578 mg/L, 17,267 mg/L, 16.921 mg/L, and 15,013 mg/L with the highest TSS pollution load occurring in 2023 and the lowest in 2021 and 2022. The average pollution load from 6 research stations in 2019 – 2023 still does not exceed the capacity limit of the Jagir River to accommodate TSS accumulation. The TSS pollution load model in the Jagir River Estuary, Surabaya, East Java, follows a quadratic pattern with the regression equation y = -173.01X2 + 2339.20X - 2299.80 (R2 = 0.7674) with a peak TSS pollution load reaching 5,607.05 tons m3/month in January and lowest in August

Cover crop impacts water quality in a tile-terraced no-till field with corn-soybean rotation

Cover crops (CCs) are a recognized best management practice to reduce surface water runoff and nutrient loss from agroecosystems. This 4-yr study was conducted in a tile-terraced field to assess the effects of CCs on nutrient loss compared to without CC (no CC) in a corn (Zea mays L.)-soybean (Glycine max L.) rotation. The 3xCCmix (wheat (Triticum aestivum L.), radish (Raphanus raphanistrum subsp. Sativus), and turnip (Brassica rapa subsp. Rapa)) was aerial seeded in soybean at R6 in 2018 and 2020. Cereal rye (Secale cereale) was drill seeded after the corn harvest in 2019 and 2021 (corn-cereal rye-soybean-3xCCmix). Water samples from individual flumes were collected using automated samplers and analyzed for concentrations and loads of nitrate-N (NO3-N), total phosphorus (TP), dissolved phosphorus (PO4-P), and total suspended solids (TSS). The 3xCCmix and cereal rye had 16% and 12% lower discharge, respectively, than no CC. The 3xCCmix reduced TSS load 50% compared to CC, while cereal rye had no effect. Cover crops reduced NO3-N load 20%, 54%, and 68% during the corn, cereal rye, and soybean growing periods, respectively. Over the full rotations, cumulative discharge and nutrient loads were greater during the 2018–20 crop rotation year because of increased precipitation in 2019. The variability in effectiveness of CCs in reducing nutrient losses was likely affected by different climatic and management factors including CC planting and termination dates. This study highlights the benefits of CCs for reducing sediment and nutrient loss over crop rotation, as well as the continued need for enhanced fertilizer management systems to reduce nutrient loss.

A novel framework for turbidity source apportionment of the urban lakeside river network

Turbidity source apportionment is essential but complex for precise environmental rehabilitation of worldwide urban lakeside river networks impaired by turbidity. A new turbidity source analysis framework including in-situ sampling, vessel monitoring, remote sensing, and hydrodynamic modelling was proposed, where the critical processes of flow reversal from the turbid lake, navigation, and urban non-point source in urban lakeside river networks were explicitly considered. The case study results showed that the turbidity problem (mean value was 211.3 nephelometricturbidityunits (NTU)) was primarily led by suspended inorganic matter (58%), followed by suspended organic matter (19%) and other matter. The Tiaoxi River and busy shipping contributed most to the annual total suspended solids load of the target river, with the same percentage of 34%. The turbid Lake Taihu provided 64,663 tonnes and 31% of the total suspended solids load, focusing on the autumn and winter months. Tiaoxi River load was highly concentrated on the storm events, which accounted for 71.4% of the annual Tiaoxi River source (209846 tonnes). The large water volume of reverse flow and the high TSS concentration of Lake Taihu in the autumn and winter months accounted for the seasonal change in Lake Taihu’s TSS load. The coronavirus disease lockdown reduced the mean monthly total suspended solids concentration of 152.4 mg/L in November and December 2019 to 49.2 mg/L in January and February 2020, by limiting the waterway transportation and the market demand for building materials. The river estuary’s vegetation interception belt, shipping restriction and rerouting, and integrated catchment management were advised to mitigate the urban river network turbidity.

Total suspended solids loading of stormwater from different land use areas in an urban watershed

Purpose. Land use within a watershed affects surface water quality by creating a process by which diffuse pollutants such as suspended solids, trace metals, and nutrients enter rivers and streams. The purpose of this study is to assess pollution-load for Total Suspended Solids (TSS) and some trace metals in runoff samples collected during storm events in selected sub-catchment locations representing different land use areas in an urban watershed; and to determine the effects of land-use on the content of pollutants in stormwater using Event Mean Concentration (EMC).&#x0D; Results. There were high EMC and Site Mean Concentrations (SMC) of TSS in stormwater in the six land-use zones examined, with values ranging from 154.0 mg L−1 to 1464.0 mg L−1; and 216.5 mg L−1 to 1153.4 mg L−1 for EMC and SMC respectively. The total content of suspended solids was significantly high, above the acceptable threshold of 100.0 mg L−1 stipulated by the WHO. The researchers also found a statistically significant variation in TSS loading of stormwater from the commercial land-use areas compared with the other land-use zones. A strong correlation was also observed between the volume of stormwater discharged and the TSS load. However, the concentrations of trace metals in stormwater were low across the land use zones. The commercial districts of the studied cities were found to be major sources of suspended solids in stormwater, and pollution of the urban watersheds leading to the deterioration of the rivers.&#x0D; Scientific novelty. This study attempted to qauntify TSS load in stormwater and determine the contributions of the diffferent urban land-use areas to pollution yield.. It contributes to scientific efforts to directly quantify surface water pollution from nonpoint sources, since little attention has been paid to diffuse pollution, especially in sub-Saharan Africa; and provides baseline data for assessing urban stormwater in low-income countries.&#x0D; Practical value. This study offers guidelines for city authorities to develop land use policies to control surface water pollution and urban waste. The findings may also serve as emperical basis for greater advocacy by civil society organizations for the proper management and control of urban rivers and streams for public health benefits.

Role of coagulation/flocculation as a pretreatment option to reduce colloidal/bio-colloidal fouling in tertiary filtration of textile wastewater: A review and future outlooks

Textile industry wastewater has become a growing concern in recent years due to it has been characterized by a high load of organic dyes, suspended and dissolved solids, alkaline pH, and low biodegradability. As a result, environmental authorities necessitate textile industries to treat effluents before discharge into the environment. Tertiary filters, particularly membrane filtrations, are the most preferable process to recover good-quality water at the tertiary treatment phase, which feeds from secondary effluents, in wastewater treatment processes. However, fouling is still a challenge due to a higher load of suspended solids, colloids, organic matter, and a high level of bio-colloids (mostly from secondary effluents) in the textile wastewater treatment process. Bio-colloids are any colloidal entities of organic matter including microorganisms and their exudates. Hence, a coagulation/flocculation unit process, as a pretreatment option, is critical both at the primary treatment stage and after secondary (biological) effluents to prevent fouling problems at the tertiary filters. We reviewed identifying major foulants causing tertiary filter damage and the available pretreatment option for the removal of these foulants. We focus on and suggest the coagulation/flocculation process as a good pretreatment alternative to prevent filter fouling as it provides a reliable process to treat high water turbidity that arises from a high load of solids and colloids. Amongst different types of foulants, we focus on and present the colloidal solids and bio-colloidal foulants that could be major causes of fouling. These foulants are less understood and expected to be dominant in the textile industry wastewater, and established pretreatment alternatives are not well developed for the bio-foulants fed from the secondary effluent. Thus, these foulants need to be critically identified in the textile wastewater treatment plants to integrate suitable pretreatment options to prevent fouling potentiality. We proposed a coagulation/flocculation unit process as a pretreatment option to reduce colloidal and bio-colloidal fouling before the tertiary treatment stage, next to the secondary effluent, is critical.

Decreasing trends in total suspended solids and cumulative effects of nonpoint source projects in the Cuyahoga River Watershed, OH

Using the US EPA’s Grants Reporting and Tracking System (GRTS), we test if completion of best management practices (BMPs) through the Clean Water Act Section (§)319 National Nonpoint Source Program was associated with a decreasing trend in total suspended solids (TSS) load (metric tons/year). The study area chosen had 21 completed projects in the Cuyahoga River watershed in northeastern Ohio from 2000 to 2018. The §319 projects ranged from dam removal, floodplain/wetland restoration to stormwater projects. There was an overall decreasing trend in TSS loads. We identified three phases of project implementation and completion, where phase 1 had ongoing projects, but none completed (2000–2004). The steepest decrease in loads, identified as phase 2 (2005–2011), was associated with completion of low-head dam modification and removal projects on the mainstem of the Cuyahoga River. A likely decreasing trend was associated with projects completed in the tributaries, such as natural channel design restoration and stormwater green infrastructure (phase 3). Pairing sediment reduction estimates from projects with the river’s flow normalized TSS loading trend, we estimated that the §319 effort may account for a small fraction of the TSS load reduction. Other stream restoration projects (non-§319) have also been done in the Cuyahoga watershed by other organizations. However, trying to compile these other projects is challenging in larger watersheds having multiple municipalities, agencies, and nonprofits doing restoration without better coordinated record keeping and monitoring. While a decreasing trend in a pollutant load is a desirable water quality outcome, determining what contributed to that trend remains difficult.

Faecal waste characteristics of yellowtail kingfish (Seriola lalandi) fed with pelleted and natural feed

Yellowtail kingfish (Seriola lalandi) is a fast-growing fish species. One of the challenges of farming yellowtail kingfish in recirculating aquaculture systems is their poor faeces integrity, also referred to as ‘diarrhoea-like’ faeces. Whether diarrhoea-like faeces occur under conditions when feeding on its natural feed items or are diet induced, is unclear. This study assessed the effect of feed type (pelleted vs. natural feed) on the faecal characteristics and faecal waste production of yellowtail kingfish. Three dietary treatments were studied over a 35-d experimental period: a pelleted diet based on marine ingredients (Marine; open formula); an experimental pelleted feed based on the ingredient composition of a commercial kingfish feed (Commercial Dummy, CD; closed formula); and a diet composed of four, individually fed raw (unprocessed) natural ingredients and commercial dummy pellets at a ratio of 1:1 on dry matter basis (Natural and Commercial Dummy, NCD). The NCD treatment was intended to clarify whether diarrhoea-like faeces are naturally occurring in yellowtail kingfish. Each dietary treatment was tested in four tanks, which were stocked with 27 yellowtail kingfish (mean initial weight 39 g). Fish were fed to apparent satiation twice daily for 1 h. For each tank nutrient digestibility and faecal characteristics were measured. The inclusion of natural ingredients reduced the faecal waste production (p < 0.001). Furthermore, the faeces integrity of yellowtail kingfish fed with natural ingredients was not poor (not diarrhoea-like). At the natural treatment, fish excreted faecal pellets and short strings, which were not observed at the other treatments. Faecal waste collected from fish receiving only pelleted feed was classified as diarrhoea-like. The highest faeces removal efficiency by settling was observed at the NCD treatment compared to the other treatments (p < 0.001). Consequently, the lowest amount of non-removed faeces per feed intake (p < 0.001) was observed at the NCD treatment (62.9 g OM/kg OM FI), followed by the Marine (101.1 g OM/kg OM FI) and Commercial Dummy treatment (111.7 g OM/kg OM FI). In conclusion, this study shows the potential of dietary interventions to alter the amount and integrity of faecal waste. This offers possibilities to reduce the total suspended solid load for yellowtail kingfish farming in recirculating aquaculture systems.

Performance Evaluation of Large-Scale Green Roofs Based on Qualitative and Quantitative Runoff Modeling Using MUSICX

Green roofs (GR) are known as one of the most effective water-sensitive urban design (WSUD) strategies to deal with numerous environmental and social issues that urbanized cities face today. The overall quality of research on GRs has significantly improved and an increasing trend is observed in the amount of research over the last decade. Among several approaches, the application of modeling tools is observed to be an effective method to simulate and evaluate the performance of GRs. Given that studies on GRs at a catchment scale are limited, this paper aims to provide a simple but effective framework for estimating the catchment-scale impacts of GR on runoff quantity and quality. MUSICX, an Australian-developed software that possesses the advantages of a conceptual model, is chosen as the modeling tool in this study. While MUSICX has built-in meteorological templates for Australian regions, this tool also supports several climate input file formats for application by modelers in other parts of the world. This paper presents two different modeling approaches using the Land Use node and Bioretention node in MUSICX. The steps used for model calibration are also provided in this paper. The modeling results present the annual reductions in runoff volume, total suspended solid (TSS), total phosphate (TP), and total nitrogen (TN) load. The largest reductions of roughly 30% per year were observed in runoff volume and TN load. The annual runoff reduction rate reported in this study is close to that of other published results. Similar research outcomes quantifying the benefits of GRs play a major role in facilitating the widespread implementation of GRs due to the awareness of both positive and negative impacts of GRs. Future studies are recommended to concentrate on modeling the impacts of implementing GRs at a large scale (i.e., scales exceeding the single-building scale) to fill the research gaps and enhance the modeling accuracy.

Evaluation of the Feasibility of Foam Glass as Filter Media in Rain Garden

Objectives:In order to recycle and resource waste glass, the feasibility of foam glass as filter media was evaluated, and column experiments using foam glass media were conducted to confirm the applicability as filter media in rain garden. Through this experiment, various design factors to be considered can be derived in application of foam glass media in the rain garden.Methods:Sieve analysis and SEM/EDS analysis were conducted to confirm the physicochemical properties of the foam glass. Column experiments filled with only foam glass and mixtures of sand and foam glass were conducted to simulate rain garden to evaluate the removal efficiency of suspended solids and turbidity using the foam glass media, head difference (&lt;i&gt;Δh&lt;/i&gt;) and hydraulic conductivity (&lt;i&gt;K&lt;/i&gt;) changes, and calculation of filtered suspended solids loading using both discrete and cumulative mass approach. Finally, comparison of filtration performance with various filter media used in LID facilities was performed to evaluate the feasibility of foam glass media in rain garden.Results and Discussion:Since foam glass media has a lower density than water, homogeneous particle size, and smooth surface with pores of various sizes, foam glass media effectively induces internal capture and external adsorption of suspended solids. Foam glass media has been applied to high suspended solids and turbidity removal efficiency. As the suspended solids inflow load increased, clogging occurred in the pores and the removal efficiency gradually decreased, but the foam glass media with lower density than water was continuously disturbed and rearranged due to the head difference energy, and some clogging were alleviated by rearrangement of pores and channels. The load of suspended solids in precipitated, adsorbed, and retained on the foam glass was calculated using the effluent sample (discrete) collected at regular time intervals and the continuously accumulated sample (cumulative) from the output. The filtered suspended solids load calculated using the cumulative mass approach was higher due to the estimation of the amounts of suspended solids remaining in the filtration column is lower because the samples (discrete) collected at regular time intervals from the output do not reflect the amount of suspended solids that change over time. Thus, the amounts of suspended solids removed through the filtration process can be much more accurately estimated using the cumulative samples. Finally, when comparing the removal efficiency with other filter media, foam glass can be used as excellent filter media with higher removal efficiency and greater lifespan.Conclusion:Foam glass media with smooth surface, pores of various sizes, and lower density than water can rearrange and regenerate pores to alleviate some clogging, resulting in high suspended solids and turbidity removal efficiency for a long period of time. Considering that the amount of suspended solids filtered is determined by various factors such as particle size and distribution, porosity, depth, linear velocity, and inflow load of the suspended solids, the feasibility test using foam glass media through long-term field experiments is warranted. The amounts of suspended solids removed through the filtration process can be much more accurately estimated using the cumulative samples.

The Relationship between Suspended Solid Loads and Dissolved Material during Floods of Various Origin in Catchments of Different Use

The paper presents the results of stationary, detailed studies on the variability of the mutual share of two fluvial loads, i.e., suspended solids and dissolved material during floods caused by rainstorm, continuous rainfalls and snowmelt in selected rivers (Silnica, Sufraganiec) draining small catchments in central Poland, including two characterized by a high level of urbanization. Irrespective of the origin of the flood, the share of suspended solids load did not exceed 80% in urbanized catchments, in suburban catchments—44%, and in forest catchments—32%. In the former, the gradient of the increase in the share of suspended solids and concentration time in the first phase of the flood was several times higher than in the other catchments. It was proved that statistically significant relationships exist between the share of sealed surfaces (roads, car parks, roofs, etc.) in the total catchment area and the average share of suspended solids, both in the rising and falling phase of the flood wave, regardless of their origin. Similar relationships were documented by analyzing: the density of the drainage network (storm sewers, roads, etc.)—the share of suspension. The obtained results have an interesting cognitive aspect and in practice are used for the development of hydrotechnical documentation related to water management in the city.

Influence of sampling frequency and estimation method on phosphorus load uncertainty in the Western Lake Erie Basin, Ohio, USA

Accurate estimates of nutrient loads are necessary to identify critical source areas and quantify the impact of management practices on pollutant export. Previous studies have investigated nutrient load estimate uncertainty, but they often focus on nutrient loads estimated using an interpolation method for large-scale watersheds with short-term datasets. The study objective was to quantify uncertainty in soluble reactive phosphorus (SRP), total phosphorus (TP), and suspended solids (SS) load estimates from two small (<103 km2) agricultural watersheds in the western Lake Erie Basin resulting from different sampling frequencies. Each watershed had high temporal resolution datasets of discharge (15 min) and nutrient concentration (1 to 3 samples per day) collected over a 30-year period (1990–2020). Firstly, SRP, TP, and SS loads were calculated using the high temporal resolution datasets, which was assumed as “true loads”. Secondly, the high temporal concentration data were decomposed to semiweekly, weekly, biweekly, and monthly sampling and annual loads were estimated using four common load estimation methods to assess the effect of sampling frequency and load estimation method on load estimate error. Across the four different methods, the composite method had the lowest relative root mean square and absolute bias, but the rectangular interpolation method was the most precise. However, even with semiweekly sampling, the composite method resulted in an unacceptable level of precision (average imprecision = 39 %), while the interpolation method resulted in an unacceptable bias (average absolute bias = 16 %). Because neither method could provide acceptable accuracy and precision at the lowest decrease in sampling (e.t. semiweekly sampling), continued daily sampling is recommended in these watersheds.

Treatment of wastewater from the production of meat and bone meal by the Fenton process and coagulation

Abstract Wastewater from the production of meat and bone meal, due to the high load of organic matter and suspended solids, is a significant problem in the process of its treatment. In this work, we examined the method of treating this wastewater using coagulation with hydrogen peroxide and the Fenton process. Treatment variants included the use of variable Fe2+/H2O2 ratios of 1:5–1:30, variable doses of 3–18.0 g/L H2O2, and 5–10 mL/L of coagulant PIX 113. The calculated reduction degrees showed that, regardless of the treatment variant used, the greatest reduction was obtained for turbidity (100%), phosphorus (99%), followed by color (97%), chemical oxygen demand (70%), and Kjeldahl nitrogen (48%). The proposed treatment options can be used as a preliminary stage in treating wastewater from the production of meat and bone meal.

Investigating the influences of concave depths on stormwater runoff and pollution retention of urban grasslands.

In this study, scale-based runoff plots of concave grasslands were designed and simulated rainfall experiments were conducted to investigate their retention effectiveness for runoff volume and pollutant loads, and to analyze the influences of concave depths on runoff and pollution retention of grasslands. Results showed that mean time to runoff of concave grasslands was 88.5 minutes, which was 5.3 times than that of flat grassland. Average peak flow rate of concave grasslands was reduced by 36.2% compared with flat grassland. Concaved grasslands averagely retained 58.2% of stormwater runoff. Deeper concave depths significantly increased runoff detention and retention performance of grasslands. Total suspended solids (TSS) load reduction rates of concave grasslands were ranged from 50.8% to 97.3%. Total nitrogen (TN) load reduction rate was 49.8% for concave depth of 10 cm. Total phosphorus (TP) load reduction rates were 45.0% and 93.9% for grasslands with 5 cm and 10 cm concave depths, respectively. Pollution load reduction rates of TSS, TN and TP enhanced along with the increase in concave depths. The estimated minimum area ratios of upslope impervious surface to grasslands of 5 cm and 10 cm concave depths were approximately 1:1 under 20 mm rainfall events, and 38:1 under 5 mm rainfalls, respectively.

Nutrient and suspended solid concentrations, loads, and yields in rivers across the Lake Winnipeg Basin: A twenty year trend assessment

Study regionThe Lake Winnipeg Basin in the northern Great Plains of North America Study focusAssessment of trends in total nitrogen (TN), total phosphorus (TP) and total suspended solids (TSS) for 18 river stations in the Lake Winnipeg Basin for the period of 1996–2016 using a Weighted Regressions on Time, Discharge and Season (WRTDS) modeling approach. New hydrological insights for the regionWe observed rapidly increasing concentrations, loads, and yields of TN, TP and TSS at most of the evaluated river monitoring stations in the eastern half of the basin. In contrast, nutrient and suspended solid loads tended to exhibit decreasing or stationary trends at most of the more western stations. Trends in nutrients and suspended solids typically corresponded to discharge, particularly in the Red-Assiniboine subdrainage where rapidly increasing nutrient loads were almost exclusively associated with runoff patterns. Our findings will serve as a baseline against which future trend assessments can be compared. Moreover, our findings suggest that land management practices aimed at reducing nutrient loads to Lake Winnipeg should be prioritized towards the rivers of the eastern subdrainages of the Lake Winnipeg basin.

Softening with Ceramic Micro-Filtration for Application on Water Reclamation for Industrial Recirculating Cooling Systems.

There is a global need for optimizing the use of water that has resulted from increased demand due to industrial development, population growth, climate change and the pollution of natural water resources. One of the solutions is to use reclaimed water in industrial applications that do not require water of potable quality, such as cooling water. However, for cooling water, (treated) wastewater’s hardness is too high, apart from having a high load of suspended solids and organic matter. Therefore, a combination of softening with ceramic micro-filtration was proposed for treating wastewater treatment effluent containing fouling agents for potential use in industrial cooling systems. The effectiveness of the softening process on model-treated wastewater with calcium hydroxide in the presence of phosphate and sodium alginate was first evaluated using jar tests. Furthermore, membrane fouling was studied when filtering the softened water. The results showed that the inhibition of calcium carbonate precipitation occurred when inorganic substances, such as phosphate and organic compounds, were present in the water. The fouling of the membranes due to sodium alginate in water was only slightly negatively affected when combined with softening and phosphate. Therefore, this combination of treatments could be potentially helpful for the post-treatment of secondary effluent for cooling systems.

SWMM stormwater quality model developed to assess the performance of best management practices: a case study of the town of Jasper in Canada

Stormwater quality management is essential for the protection of aquatic life of receiving waterbodies. This study presents a unique case study, whereby a stormwater management model (SWMM) was developed to assess the performances of street sweeping and infiltration trenches to reduce total suspended solids (TSS) loads in the Town of Jasper located in Jasper National Park, AB, Canada. Two catchment models were developed for the Town using long-term meteorological data, as well as watershed and drainage system data provided by the Municipality of Jasper. The quality parameters were calibrated so that TSS loads at the outfalls were within a 20% error of monitoring data. The performance of proposed best management practices was assessed using single-event and continuous data simulations. The results indicated that a combined sweeping/trench control scenario would generate the highest TSS removal efficiency of up to 51%.