Suspended Solids Loads Research Articles

Nitrogen, Phosphorus, Carbon, and Suspended Solids Loads from Forest Clear-Cutting and Site Preparation: Long-Term Paired Catchment Studies from Eastern Finland

The long-term impacts of current forest management methods on surface water quality in Fennoscandia are largely unexplored. We studied the long-term effects of clear-cutting and site preparation on runoff and the export of total nitrogen (total N), total organic nitrogen (TON), ammonium (NH(4)-N), nitrate (NO(3)-N), total phosphorus (total P), phosphate (PO(4)-P), total organic carbon, and suspended solids (SS) in three paired-catchments in Eastern Finland. Clear-cutting and soil preparation were carried out on 34 % (C34), 11 % (C11), and 8 % (C8) of the area of the treated catchments and wide buffer zones were left along the streams. Clear-cutting and soil preparation increased annual runoff and total N, TON, NO(3)-N, PO(4)-P, and SS loads, except for SS, only in C34. Runoff increased by 16 % and the annual exports of total N, TON, NO(3)-N, and PO(4)-P by 18, 12, 270, and 12 %, respectively, during the 14-year period after clear-cutting. SS export increased by 291 % in C34, 134 % in C11, and 16 % in C8 during the 14, 6, and 11-year periods after clear-cutting. In the C11 catchment, NO(3)-N export decreased by 12 %. The results indicate that while current forest management practices can increase the export of N, P and SS from boreal catchments for many years (>10 years), the increases are only significant when the area of clear cutting exceeds 30 % of catchment area.

Review of environmental performance of permeable pavement systems: state of the knowledge

Permeable pavement (PP) systems provide opportunities to mitigate the impacts of urbanization on receiving water systems by providing at source treatment and management of stormwater. However, they do not receive mainstream use throughout much of Canada and the USA because of a lack of local guidance documents, demonstration projects and performance data. Studies have repeatedly shown that PPs attenuate stormwater flows by reducing volume and frequency of stormwater flows, reducing and delaying peak flow rates, and increasing flow durations. PP systems have been shown to improve stormwater quality by reducing stormwater temperature, pollutant concentrations and pollutant loadings of suspended solids, heavy metals, polyaromatic hydrocarbons, and some nutrients. This review is intended as a comprehensive summary of the current state of knowledge of the environmental performance of PP systems. Published research is synthesized to examine the hydrologic performance, impacts to water quality, longevity and functionality and maintenance needs of PP systems. Where appropriate, the limitations of current knowledge are discussed and emerging and future research needs are presented. The intent of this review is to provide stakeholders in stormwater management with the critical information that is needed to foster acceptance of PPs as a viable alternative to traditional systems.

Nitrogen and Phosphorous Movement Characteristic in Terrace Paddy Field Using Cascade Irrigation System in West Sumatra, Indonesia

West Sumatra is one of Indonesian rice bowl. The landscape of this province dominated by mountainous area with beautiful terrace paddy field lied from the middle slope to the lowland. The most common rice cultivation management in this area is application of cascade irrigation system with blanked amount of chemical fertilizer application. This study intends to figure out, whether this kind of paddy field management sustains and friendly to the environment or not. The results showed that cascade irrigation system created some discrepancies in suspended solid (SS), dissolve organic matter (DOM) and the nutrient movement characteristic a long the slope. The SS and DOM load and discharge strongly influenced by land preparation activities, while total and available nitrogen (N) and phosphorous (P) affected by chemical fertilizer application. In the upper part, the amount of chemical fertilizer seemed sufficient, indicated by negative amount of nutrient balance, while lower terrace show some indication of excess nutrient input. To avoid some demerit of cascade irrigation system, chemical fertilizer application should be base on site specific characteristic and taking into account of natural source contribution.Keywords: Cascade irrigation, chemical fertilizer, nutrient balance, terrace paddy field

Novel Measurements in Primary Settling Tanks of Large Municipal Wastewater Treatment Plants

Abstract This paper shows the in situ analysis of a primary settling tank (PST) at the Graz Municipal Wastewater Treatment Plant (500 000 PE). The study aims at the deeper understanding of primary settling tanks behaviour by measurement of flow pattern within the tank and suspended solids (SS) separation. Measurement campaigns were carried out at different surface overflow rates (a main measure of PST load), that ranged from low to even higher values than recommended ones by design guidelines. During the measurements the inflowing and outflowing SS concentrations and loads were registered on-line. The flow pattern (3D velocity measurements, turbulence characteristics) was measured by using Acoustic - Doppler - Velocimetry (ADV) in raster [1]. The settling function was carried out by laboratory test at Budapest Central Wastewater Treatment Plant, which was investigated at representative concentration of PST. The measurements provided detailed insight into the flow and mass transport processes within the PST and valuable calibration and verification data for further CFD modelling.

A practical model to describe temporal variations in total suspended solids concentrations in highway runoff

Techniques to predict temporal variations in concentrations and loads of suspended solids from highway runoff are required to estimate impacts on receiving water ecology and to inform the design of interception/treatment devices. A recent UK study included the collection of rainfall, highway runoff rates and sediment load and quality data from six different sites where motorway runoff drained directly into a receiving watercourse. This data set is used to critically evaluate a previously-published model (Kim et al. 2005) aimed at predicting temporal variations in runoff quality. The comparisons, based on discrete samples collected during 21 storm events, suggest that a simplification of the model, requiring just two parameters, provides a robust estimate of temporal variations in total suspended solids (TSS). Generic parameter values are provided, and the model’s application is illustrated. The model captures first flush effects well, but the identified generic parameters fail to fullypredict the variation in absolute TSS values that are observed in practice.

Comparison of runoff quantity and quality under annual cropping and forages

Conversion from annual cropping to perennial forages may be a beneficial management practice (BMP) to reduce runoff quantity and improve surface water quality. Runoff variables were determined in two 30 ha producer's fields over 4 years (2004–2007) using a rainfall simulator. Field 1 was cropped to barley (Hordeum vulgare L.) in 2004 and then an alfalfa (Medicago sp.) and grass mix used for hay and fall grazing was grown from 2005 to 2007. Field 2 was cropped to barley-winter triticale (WT) (Triticosecale Rimpavi Wittm.) in 2005 and alfalfa-grass for hay was grown in 2006 and 2007. Runoff variables measured were runoff depth, electrical conductivity, and concentrations and loads of total suspended solids, total N, total P, and dissolved reactive P fractions. Conversion from barley to alfalfa-grass for hay and fall grazing in Field 1 resulted in reductions for only 13% of the 10 runoff variables, 33% of runoff variables were unaffected, and 53% of variables were significantly increased. Conversion from barley-WT to alfalfa-grass used for hay in Field 2 significantly reduced 25% of the 10 variables, 40% were unaffected, and 35% were significantly increased. Converting from annual cropping to forage did not improve the majority of runoff variables.

Measuring bluff erosion part 2: pairing aerial photographs and terrestrial laser scanning to create a watershed scale sediment budget

ABSTRACTEffectively managing and reducing high suspended sediment loads in rivers requires an understanding of the magnitude of major sediment sources as well as erosion and transport processes that deliver excess fine sediments to the channel network. The focus of this research is to determine the magnitude of erosion from tall bluffs, a primary sediment source in the 2880 km2 Le Sueur watershed, Minnesota, USA. We coupled analyses of seven decades of aerial photographs with four years of repeat terrestrial laser scanning (TLS) to determine erosion rates on bluffs. Together, these datasets provide decadal‐scale retreat rates throughout the entire watershed and high‐resolution geomorphic change detection on a subset of bluffs to both constrain erosion rates and document how environmental conditions affect bluff retreat. Erosion rates from aerial photographs and TLS were extrapolated from 243 and 15 measured bluffs, respectively, to all 480 bluffs in the Le Sueur watershed using multiple techniques to obtain estimates of sediment loading from these features at the watershed‐scale. Despite different spatial and temporal measurement scales, the aerial photograph and TLS estimates yielded similar results for bluff retreat rate and total mass of sediment derived from bluffs, with bluffs in the Le Sueur watershed yielding 135 000 ± 39 000 Mg/yr of fine sediment. Comparing this value to the average annual total suspended solids (TSS) load determined from gauging from 2000 to 2010, we determined that bluffs comprise 57 ± 16% of the total TSS load, making bluffs the single most abundant fine sediment source in the basin. Copyright © 2012 John Wiley & Sons, Ltd.

Restoration of “dead” clay fouled membranes

Without doubt, the membrane is the key component of a Reverse Osmosis (RO) system, but the pretreatment system is often the most important contributor to the smooth and efficient operation of a membrane plant. This is especially true when treating challenging source waters such as highly turbid surface waters from open canals, rivers, and lakes. These are often contaminated with a variety of organics that have complex and variable chemistries and can carry large loads of suspended solids. Amongst these are the clay minerals, (alumino-silicates), derived from the weathering of rocks and the entrainment of soils, which create a particularly difficult fouling. Over 100 RO plants in the Karachi area are affected by this type of fouling which is characterized by high 1st stage differential pressure (ΔP) and loss of flux. The clay forms a layer on the membrane surface which is impervious to water and so feed pressures are increased to maintain permeate flow, resulting in increased energy costs due to higher consumption of electricity. Permeate quality is also affected by impregnated clay interfering with the salt rejection properties of the membrane. This article presents the results of cleaning experiments conducted on completely fouled membranes and to all intents ‘Dead’ membranes from a system treating such canal water. Cleanings were performed with conventional commodity chemicals, a series of proprietary products, and finally with a specialist product (Genesol-703) specifically designed for the removal of clay fouling. In conducting the experiments, a specific method of application was derived which gives extremely good results.

諫早湾干拓調整池流域における雨天時の汚濁負荷流出量の予測

Recently, the reduction of pollutant load from watershed becomes significant issue for the water quality management at a closed water area. Countermeasure for the nonpoint pollution load is urgently needed. In this study, to predict and estimate the amount of pollutant runoff from watershed under the rain condition, a numerical model was developed. The rainfall-runoff relation was calculated by the runoff function method, and the amount of pollutant-runoff was represented as the function of specific discharge. This model was applied to the prediction of the temporal variation of suspended solids (SS) at four rivers which are flowing into Isahaya flood regulation pond, Nagasaki. Computed results of the flood discharge and the runoff load of SS have good agreements with observed results, and the usefulness of this model was shown.

First record of Cordylophora caspia (Hydrozoa: Cnidaria) in the Tagus estuary, central Portugal

The Ponto-Caspian hydroid Cordylophora caspia has been found for the first time in the Tagus estuary. There is only one previous citation for this invasive species in Portuguese waters. The colonies of C. caspia were branched and had healthy gastrozooids and gonophores. The specimens were collected from a saline boundary zone characterized by high fluctuations in salinity (maximum of 15.3 and minimum of 0.2) and high suspended solids loading. Cordylophora caspia is capable of colonizing man-made infrastructures such as industrial facilities and can inhabit both brackish and freshwater environments. These features of C. caspia, together with its resilience when in a dormant stage (menonts), indicate that the monitoring of this invasive species is advisable in the Tagus estuary.

합류식 하수관거내 우오수분리벽 설치에 따른 부유물질 제어효과

The purpose of this study is to investigate CSOs(combined sewer overflows) control in the combined sewer with/without separation wall. There is the high correlation between sewage velocity and suspended solid(SS) loading in the sewer without it. The SS/BOD ratio was about 3 times in the area with it, while it was about 5 times in the area without it. Therefore, the accumulated deposit within the sewer has influenced high SS loading in the sewer without it. This study showed that the separation wall installed acquired an acceptable efficiency in controlling the accumulated deposit in the combined sewer. According to this study, the BOD control effect was about 38 % in the sewer with the separation wall, whereas it showed about 24 % in the sewer without it. In this case, it was anticipated that the high pollutant control effect would be expected if the separation wall was installed in the combined sewer.

Avoiding clogging in constructed wetlands by using anaerobic digesters as pre-treatment

The main operational problem of subsurface flow constructed wetlands (CWs) is clogging of granular medium, a phenomenon related to the accumulation of different types of solids that lead to a reduction of the infiltration capacity of the gravel bed. It is generally accepted that the application of a good wastewater pre-treatment is essential for the long-term operation of subsurface flow CW. Anaerobic digesters (ADs) could help to the aim of clogging prevention. Two combined AD-CW treating either municipal or winery wastewater were designed and monitored for trough performance and efficiency parameters, solids accumulation and hydraulic conductivity, over a long term period. CW operated at high organic loading rates in terms of TCOD and BOD5 while suspended solids loading rates and solids accumulation in CW were lower. In turn, CW maintained an adequate hydraulic conductivity and low rates of solids accumulation.

Development of a water quality modeling system for river pollution index and suspended solid loading evaluation

Summary The Kaoping River Basin is the largest and most extensively used watershed in Taiwan. In the upper catchment, the non-point source (NPS) pollutants including suspended solid (SS) and ammonia nitrogen (NH 3 –N) are two major water pollutants causing the deterioration of Kaoping River water quality. Because SS is one of the four parameters involving in the River Pollution Index (RPI) calculation, it needs to be carefully evaluated to obtain the representative water quality index. The main objective of this study was to develop a water quality modeling system to obtain representative SS and RPI values for water quality evaluation. In this study, a direct linkage between the RPI calculation and a water quality model [Water Quality Analysis Simulation Program (WASP)] has been developed. Correlation equations between Kaoping River flow rates and SS concentrations were developed using the field data collected during the high and low flows of the Kaoping River. Investigation results show that the SS concentrations were highly correlated with the flow rates. The obtained SS equation and RPI calculation package were embedded into the WASP model to improve interactive transfers of required data for water quality modeling and RPI calculation. Results indicate that SS played an important role in RPI calculation and SS was a critical factor during the RPI calculation especially for the upper catchment in the wet seasons. This was due to the fact that the soil erosion caused the increase in the SS concentrations after storms. In the wet seasons, higher river flow rates caused the discharges of NPS pollutants (NH 3 –N and SS) into the upper sections of the river. Results demonstrate that the integral approach could develop a direct linkage among river flow rate, water quality, and pollution index. The introduction of the integrated system showed a significant advance in water quality evaluation and river management strategy development.

Occurrence and fate of dissolved and particulate antimicrobials in municipal wastewater treatment

Comprehensive study on the occurrence and fate of several classes of antimicrobials, including sulfonamides, trimethoprim, fluoroquinolones and macrolides, in Croatian municipal wastewaters was performed using an integrated approach, which comprised analysis of both dissolved and particulate fractions. A nation-wide screening showed ubiquitous occurrence of human-use antimicrobials in raw wastewater samples with the total concentrations ranging from 2 to 20 μg/L, while veterinary antimicrobials were typically present in much lower concentrations (<100 ng/L). The percentage of the particulate fraction in raw wastewater varied significantly depending on the type of the antimicrobial and the load of suspended solids. A detailed study of the mass flows of dissolved and particulate antimicrobials, performed in the wastewater treatment plant of the city of Zagreb, allowed an improved assessment of the biological and physico-chemical removal mechanisms of investigated compounds during the conventional activated sludge treatment. The overall removal efficiencies of antimicrobials from the water phase were rather variable, ranging from 0% for trimethoprim to 85% for norfloxacin. A significant percentage of fluoroquinolones (norfloxacin and ciprofloxacin) and macrolides (azithromycin and clarithromycin) was associated with the primary and excess secondary sludge, explaining 14–77% of the total removal. The removal, which could be attributed to biological transformation, was relatively poor for all antimicrobials, exceeding 30% only for SMX (32%) and clarithromycin (55%).

High Pollutant Removal Efficacy of a Large Constructed Wetland Leads to Receiving Stream Improvements

Hewletts Creek, in Wilmington, North Carolina, drains a large suburban watershed and as such is affected by high fecal bacteria loads and periodic algal blooms from nutrient loading. During 2007, a 3.1-ha wetland was constructed to treat stormwater runoff from a 238-ha watershed within the Hewletts Creek drainage. A rain event sampling program was performed in 2009-2010 to evaluate the efficacy of the wetland in reducing pollutant loads from the stormwater runoff passing through the wetland. During the eight storms sampled, the wetland greatly moderated the hydrograph and retained and/or removed 50 to 75% of the inflowing stormwater volume. High removal rates of fecal coliform bacteria were achieved, with an average load reduction of 99% and overall concentration reduction of >90%. Particularly high (>90%) reductions of ammonium and orthophosphate loads also occurred, and lesser but still substantial reductions of total phosphorus (89%) and total suspended solids loads (88%) were achieved. Removal of nitrate was seasonally dependent, with lower removal occurring in cold weather and a high percentage (90%+) of nitrate load removal occurring in the growing season when water temperature exceeded 15°C. Long-term before-and-after sampling in downstream Hewletts Creek proper showed that, after wetland construction, statistically significant average decreases of 43% for nitrate, 72% for ammonium, and 59% for fecal coliform bacteria were realized. Wetland features contributing to the high pollutant control efficacy included available space for a large wetland, construction of deep forebays, and a dense and diverse aquatic and shoreline plant assemblage.

The magnitude of variability produced by methods used to estimate annual stormwater contaminant loads for highly urbanised catchments

Stormwater contaminant loading estimates using event mean concentration (EMC), rainfall/runoff relationship calculations and computer modelling (Model of Urban Stormwater Infrastructure Conceptualisation--MUSIC) demonstrated high variability in common methods of water quality assessment. Predictions of metal, nutrient and total suspended solid loadings for three highly urbanised catchments in Sydney estuary, Australia, varied greatly within and amongst methods tested. EMC and rainfall/runoff relationship calculations produced similar estimates (within 1 SD) in a statistically significant number of trials; however, considerable variability within estimates (∼50 and ∼25 % relative standard deviation, respectively) questions the reliability of these methods. Likewise, upper and lower default inputs in a commonly used loading model (MUSIC) produced an extensive range of loading estimates (3.8-8.3 times above and 2.6-4.1 times below typical default inputs, respectively). Default and calibrated MUSIC simulations produced loading estimates that agreed with EMC and rainfall/runoff calculations in some trials (4-10 from 18); however, they were not frequent enough to statistically infer that these methods produced the same results. Great variance within and amongst mean annual loads estimated by common methods of water quality assessment has important ramifications for water quality managers requiring accurate estimates of the quantities and nature of contaminants requiring treatment.

The effect of reservoir operational features on recycled wastewater quality

Israel's wastewater recycling program is unprecedented internationally, with close to 80% of sewage treated and reused in agriculture. This article presents findings from a national survey of Israel's wastewater reservoir network. Israel's extensive reuse of wastewater is possible due to a national network of reservoirs that has been established in recent years. Sixty effluent reservoirs presently operating in all parts of Israel, were reviewed and evaluated for static data and sampled for water quality analysis during the intensive irrigation season of 2008. The measurement of 16 chemical, physical and biological parameters, along with 21 major and trace elements was carried out, revealing a wide range of concentrations that reflect reservoir physical and operational characteristics. Results indicate that 65% and 78% of the supplied wastewater volume met the old 20mg/L BOD and 30mg/L TSS regulations for unlimited irrigation. With reference to Israel's updated, more stringent, regulations, only 22% and 28% of the supplied wastewater volume met the new TSS and E.C. regulations for unlimited irrigation, respectively, and only 48%, 58%, 58% and 62% met the new BOD, fecal coliforms, chloride and sodium regulations for unlimited new irrigation, respectively. All measured major and trace elements were well under existing standards, although there were considerable regional variation. Both principal component analysis and redundancy analysis were used to examine how the wastewater quality relates to multiple static construction features and operational parameters of the studied reservoirs. Sewage treatment plant technology, along with the reservoir operational regime, were found to have the greatest influence on the organic, nutrient and suspended solids loads of the wastewater supplied. The geographic location of the reservoirs along with their designed area to volume ratio, were found to have the largest influence over salinity components loads. Careful consideration should be given to the aforementioned features in future the reservoir planning process.

Influence of Sampling Frequency on Estimation of Annual Total Phosphorus and Total Suspended Solids Loads1

Abstract: The determination of sediment and nutrient loads is typically based on the collection and analysis of grab samples. The frequency and regularity of traditional sampling may not provide representation of constituent loading, particularly in systems with flashy hydrology. At two sites in the Little Bear River, Utah, continuous, high‐frequency turbidity was used with surrogate relationships to generate estimates of total phosphorus and total suspended solids concentrations, which were paired with discharge to estimate annual loads. The high frequency records were randomly subsampled to represent hourly, daily, weekly, and monthly sampling frequencies and to examine the effects of timing, and resulting annual load estimates were compared to the reference loads. Higher frequency sampling resulted in load estimates that better approximated the reference loads. The degree of bias was greater at the more hydrologically responsive site in the upper watershed, which required a higher sampling frequency than the lower watershed site to achieve the same level of accuracy in estimating the reference load. The hour of day and day of week of sampling impacted load estimation, depending on site and hydrologic conditions. The effects of sampling frequency on the determination of compliance with a water quality criterion were also examined. These techniques can be helpful in determining necessary sampling frequency to meet the objectives of a water quality monitoring program.

Stormwater runoff pollution loads from an urban catchment with rainy climate in China

An older urban district in Wuhan, China, is transitioning from discharging sewage and stormwater directly into lakes, to directing the sewage to wastewater treatment plants (WWTPs). Dealing with polluted stormwater discharge is a great challenge. Stormwater runoff from an urban catchment with a combined sewer system was sampled and analyzed over a three-year period. Results indicate that wet weather flows account for 66%, 31%, 17%, and 13% of the total load of suspended solids (SS), chemical oxygen demand (COD), total nitrogen, and total phosphorus, respectively. The first flush of COD and SS was significant in all runoff events. More than 50% of the SS and COD loads were transported by the first 30% of runoff volume. Storage and treatment of the first 10 mm from each combined sewer overflow event could reduce more than 70% of the annual COD overflow load. An integrated solution is recommended, consisting of a tank connected to the WWTP and a detention pond, to store and treat the combined sewer overflow (CSO). These results may be helpful in mitigating CSO pollution for many other urban areas in China and other developing countries.

SSUIS – a research model for predicting suspended solids loads in stormwater runoff from urban impervious surfaces

Suspended solids from urban impervious surfaces (SSUIS) is a spreadsheet-based model that predicts the mass loading of suspended solids (SS) in stormwater runoff generated from impervious urban surfaces. The model is intended to be a research tool and incorporates several particle accumulation and washoff processes. Development of SSUIS is based on interpretation of storm event data obtained from a galvanised iron roof, a concrete car park and a bitumen road located in Toowoomba, Australia. SSUIS is a source area model that tracks the particle mass balance on the impervious surface and within its lateral drain to a point of discharge. Particles are separated into two groups: free and detained, depending on the rainfall energy required for surface washoff. Calibration and verification of SSUIS against the Toowoomba SS data yielded R(2) values ranging from 0.60 to 0.98. Parameter sensitivity analysis and an example of how SSUIS can be applied to predict the treatment efficiency of a grass swale are also provided.