An Innovative Approach to Tracking Sediment Transport along Roads

A study of sediment transport was carried out in the New England area of the United States where large quantities of sediments and other debris accumulate along roads. These sediments are mostly transported by roadway runoff and stormwater drainage structures, where present, tend to concentrate them. However, polluted sediments might also find their way into ecologically sensitive areas. Our research aimed at tracking the transport of these sediments as they move along a road. Further, we attempted to quantify the rate by which the sediments were transported. Glass microbeads in the size range of sand were released as a tracer of sediment transport at six comparable locations. Over a period of 10 months, their movement was tracked using microscopy. Our results indicate that this type of tracer was successful in following along the sediment transport. More research is required to establish this new method under different stormwater runoff regimes or different roadside maintenance conditions

Induced Bank Filtration: Hydraulic Testing of Pilot Filters

Hydraulic tests were performed on two pilot scale filters as part of a water treatment project in the village of Nersa, Karnataka, India. The filters use locally sourced alluvial material to filter E.coli contamination using natural processes that mimic those in Riverbank Filtration (RBF). Two pilot scale filters were tested, one containing locally sourced granular activated carbon (GAC) and one without. A falling head test and tracer test were preformed, and breakthrough curves were used to analyze the hydraulic performance. E.coli data were also collected, and percent removal was calculated to determine the effectiveness of the filters. Relative to the influent water, the E.coli removal percentage of Filter 1 (no GAC) was consistently high and ranged between 97.1% and 100% E.coli. The addition of GAC did not improve performance in this study. Overall, the effectiveness in bacteria removal observed in the non GAC filter warranted construction of a full-scale system

Sustainable Water Treatment with Induced Bank Filtration

This study demonstrates that an induced bank filter (IBF) system can treat raw water polluted with Escherichia coli (E. coli) bacteria. Similar to riverbank filtration (RBF), induced or reversed bank filtration relies on natural processes to clean water, including filtration through layers of allochthone alluvial sediments and a bioactive layer that forms on top of the filter after a ripening period. At the study site, located in Southwestern India, villagers rely on a mountain spring for their water supply. Although of generally high quality, the spring water contains E. coli bacteria (up to ~2000 MPN/100 mL). Raw water diverted from this spring was gravity-fed into the IBF system, which consisted of a (1) flow regulator, (2) pre-filter and (3) the actual IBF filter. Designed and constructed based on pilot testing of prototype filters, a full-scale filter (5 m by 7 m by 2 m) was built and its performance and maintenance requirements were studied during both the monsoon season and the dry season. The data show that the IBF significantly improved the water quality. Turbidity and E. coli concentrations were reduced to or below the detection limit (approximately 2.5 log unit reduction). During the peak of the monsoon season (August), E. coli was present in the IBF effluent after a storm destroyed the cover of the IBF tank. The IBF construction and maintenance costs were documented. Extrapolated over a 10-year period, the cost of IBF water was 3 and 10 times lower than reverse osmosis or water supplied by truck, respectively. This study demonstrates that IBF can be part of an affordable water supply system for rural villages in mountainous terrain where conventional RBF systems cannot be installed or where other water treatment technologies are out of financial reach

Floating Wetlands System: A Viable Alternative for Water Pollutants Remediation

Constructed floating wetlands is viable alternative for the treatment of stormwater, combined stormwater-sewer overflow, sewage and water supply reservoirs, among others. The use of this technology also allows to enhance the habitat, and improve aesthetics to the treatment facility. In brief, the constructed floating wetlands island treatment mechanism is a combination of several components and physico-chemical processes that mimic natural bioremediation. Plant roots play a major role in treatment processes within constructed floating wetland island since the water passes directly through root system underneath the floating mat. Pathways for contaminant removal/retention in floating wetland island are: release of extracellular enzymes, development of biofilms, flocculation of suspended matter, and plant uptake. This study summarizes the findings of four monitoring studies and emphasizes on the field studies that monitored how pond contaminants responded to the floating wetlands through extensive review of existing literature

Runoff treatment with aspen wood

Runoff from roadways and urban areas is often contaminated with heavy metals such as zinc and copper. The use of aspen wood (Populus tremula) was investigated as a potential sorbentfor these metal contaminated runoff waters. The objective was to design an alternative runoff treatment technology based on a renewable resource, i.e. wood. Laboratory isotherms and column experiments were conducted in order to investigate the sorption and desorption of dissolved copper and zinc to and from aspen wood fibers. Sorption ofCu(II) and Zn(II) followed non-linear Freundlich isotherms. The aspen wood-water partition coefficient values revealed that Cu(II) had a greater tendency to sorb to the aspen wood than Zn(II). The column experiments indicated that, at least initially, both metals were being rapidly sorbed. During later stages of the sorption experiments, slower, but steady transport of the metal ions into the wood fibers appeared to be the dominating removal mechanism. Desorption of copper with E-pure water was faster than zinc, but the total amount of metal mass released from the wood was small in both cases, i.e., only 2% to 4% of the amount sorbed. Although initial dissolved metal removal data from an ongoing field test is inconclusive, it was shown that a proto-type wood filter and a viable runoff treatment technology can be build around wood-based filte

Transport of Pathogen Surrogates in Soil Treatment Units: Numerical Modeling

Segmented mesocosms (n = 3) packed with sand, sandy loam or clay loam soil were used to determine the effect of soil texture and depth on transport of two septic tank effluent (STE)-borne microbial pathogen surrogates—green fluorescent protein-labeled E. coli (GFPE) and MS-2 coliphage—in soil treatment units. HYDRUS 2D/3D software was used to model the transport of these microbes from the infiltrative surface. Mesocosms were spiked with GFPE and MS-2 coliphage at 105 cfu/mL STE and 105–106 pfu/mL STE, respectively. In all soils, removal rates were \u3e99.99% at 25 cm. The transport simulation compared (1) optimization; and (2) trial-and-error modeling approaches. Only slight differences between the transport parameters were observed between these approaches. Treating both the die-off rates and attachment/detachment rates as variables resulted in an overall better model fit, particularly for the tailing phase of the experiments. Independent of the fitting procedure, attachment rates computed by the model were higher in sandy and sandy loam soils than clay, which was attributed to unsaturated flow conditions at lower water content in the coarser-textured soils. Early breakthrough of the bacteria and virus indicated the presence of preferential flow in the system in the structured clay loam soil, resulting in faster movement of water and microbes through the soil relative to a conservative tracer (bromide)

The Case for LED-UVC as a Primary Disinfectant for Small Sustainable Drinking Water Systems

High loads of natural organic matter (NOM) in source water increase levels of toxic byproducts during disinfection, including trihalomethanes (THMs) which are formed when NOM is chlorinated. This study explores the efficacy of using UVC-LED as a primary disinfectant, with lower concentrations of chlorine used as a secondary disinfectant. Both treatment trains with conventional chlorination and UV irradiation with low chlorination reduced total coliforms and E.Coli counts to less than 1 Cfu/100 ml. UV with low chlorination produced approximately 4.6 times less THMs compared to conventional chlorination

Use of α-cyclodextrin to Promote Clean and Environmentally Friendly Disinfection of Phenolic Substrates via Chlorine Dioxide Treatment

The use of chlorine dioxide to disinfect drinking water and ameliorate toxic components of wastewater has significant advantages in terms of providing safe water. Nonetheless, significant drawbacks toward such usage remain. These drawbacks include the fact that toxic byproducts of the disinfection agents are often formed, and the complete removal of such agents can be challenging. Reported herein is one approach to solving this problem: the use of α-cyclodextrin to affect the product distribution in chlorine dioxide-mediated decomposition of organic pollutants. The presence of α-cyclodextrin leads to markedly more oxidation and less aromatic chlorination, in a manner that is highly dependent on analyte structure and other reaction conditions. Mechanistic hypotheses are advanced to explain the cyclodextrin effect, and the potential for use of α-cyclodextrin for practical wastewater treatment is also discussed

An innovative approach to tracking sediment transport along roads

A study of sediment transport was carried out in the New England area of the United States where large quantities of sediments and other debris accumulate along roads. These sediments are mostly transported by roadway runoff and stormwater drainage structures, where present, tend to concentrate them. However, polluted sediments might also find their way into ecologically sensitive areas. Our research aimed at tracking the transport of these sediments as they move along a road. Further, we attempted to quantify the rate by which the sediments were transported. Glass microbeads in the size range of sand were released as a tracer of sediment transport at six comparable locations. Over a period of 10 months, their movement was tracked using microscopy. Our results indicate that this type of tracer was successful in following along the sediment transport. More research is required to establish this new method under different stormwater runoff regimes or different roadside maintenance conditions

Floating Wetlands System: A viable alternative for water pollutants remediation

Constructed floating wetlands is viable alternative for the treatment of stormwater, combined stormwater-sewer overflow, sewage and water supply reservoirs, among others. The use of this technology also allows to enhance the habitat, and improve aesthetics to the treatment facility. In brief, the constructed floating wetlands island treatment mechanism is a combination of several components and physico-chemical processes that mimic natural bioremediation. Plant roots play a major role in treatment processes within constructed floating wetland island since the water passes directly through root system underneath the floating mat. Pathways for contaminant removal/retention in floating wetland island are: release of extracellular enzymes, development of biofilms, flocculation of suspended matter, and plant uptake. This study summarizes the findings of four monitoring studies and emphasizes on the field studies that monitored how pond contaminants responded to the floating wetlands through extensive review of existing literature