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2050 KiB

Open AccessArticle

Upflow Evapotranspiration System for the Treatment of On-Site Wastewater Effluent

by Sean Curneen and Laurence Gill

Water 2015, 7(5), 2037-2059; https://doi.org/10.3390/w7052037 - 06 May 2015

Cited by 11 | Viewed by 6228

Full-scale willow evapotranspiration systems fed from the base with septic tank or secondary treated domestic effluent from single houses have been constructed and instrumented in Ireland in order to investigate whether the technology could provide a solution to the problem of on-site effluent [...] Read more.

Full-scale willow evapotranspiration systems fed from the base with septic tank or secondary treated domestic effluent from single houses have been constructed and instrumented in Ireland in order to investigate whether the technology could provide a solution to the problem of on-site effluent disposal in areas with low permeability subsoils. Continuous monitoring of rainfall, reference evapotranspiration, effluent flows and water level in the sealed systems revealed varying evapotranspiration rates across the different seasons. No system managed to achieve zero discharge in any year remaining at maximum levels for much of the winter months, indicating some loss of water by lateral exfiltration at the surface. Water sampling and analysis however, showed that the quality of any surface overflow from the systems was similar to rainfall runoff. The performance results have then been used to formulate design guidelines for such systems in Ireland’s temperate maritime climate. The effect of varying different combinations of design parameters (plan area, soil depth, etc.) has been evaluated with respect to the simulated number of overflow days over a five-year period using a water balance model. Design guidelines have then been based upon minimising the amount of runoff, in conjunction with other practical and financial considerations. Full article

(This article belongs to the Special Issue Advances in On-Site Wastewater Treatment and Technologies to Characterize the Fate and Transport of Wastewater Constituents)

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1137 KiB

Open AccessArticle

Effectiveness of Domestic Wastewater Treatment Using a Bio-Hedge Water Hyacinth Wetland System

by Alireza Valipour, Venkatraman Kalyan Raman and Young-Ho Ahn

Water 2015, 7(1), 329-347; https://doi.org/10.3390/w7010329 - 19 Jan 2015

Cited by 81 | Viewed by 19332

Abstract

onstructed wetland applications have been limited by a large land requirement and capital investment. This study aimed to improve a shallow pond water hyacinth system by incorporating the advantages of engineered attached microbial growth technique (termed Bio-hedge) for on-site domestic wastewater treatment. A [...] Read more.

onstructed wetland applications have been limited by a large land requirement and capital investment. This study aimed to improve a shallow pond water hyacinth system by incorporating the advantages of engineered attached microbial growth technique (termed Bio-hedge) for on-site domestic wastewater treatment. A laboratory scale continuous-flow system consists of the mesh type matrix providing an additional biofilm surface area of 54 m²/m³. Following one year of experimentation, the process showed more stability and enhanced performance in removing organic matter and nutrients, compared to traditional water hyacinth (by lowering 33%–67% HRT) and facultative (by lowering 92%–96% HRT) ponds. The wastewater exposed plants revealed a relative growth rate of 1.15% per day, and no anatomical deformities were observed. Plant nutrient level averaged 27 ± 1.7 and 44 ± 2.3 mg N/g dry weight, and 5 ± 1.4 & 9±1.2 mg P/g dry weight in roots and shoots, respectively. Microorganisms immobilized on Bio-hedge media (4.06 × 10⁷cfu/cm²) and plant roots (3.12 × 10⁴cfu/cm) were isolated and identified (a total of 23 strains). The capital cost was pre-estimated for 1 m³/d wastewater at 78 US$/m³_inflow and 465 US$/kg BOD_{5 removed}. This process is a suitable ecotechnology due to improved biofilm formation, reduced footprint, energy savings, and increased quality effluent. Full article

(This article belongs to the Special Issue Advances in On-Site Wastewater Treatment and Technologies to Characterize the Fate and Transport of Wastewater Constituents)

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395 KiB

Open AccessArticle

Sorption of Emerging Organic Wastewater Contaminants to Four Soils

by Sarah Roberts, Christopher Higgins and John McCray

Water 2014, 6(4), 1028-1042; https://doi.org/10.3390/w6041028 - 24 Apr 2014

Cited by 16 | Viewed by 7170

Abstract

Conventional onsite wastewater treatment system design relies on a septic tank and soil treatment unit (STU) for treatment of wastewater and integration of the final effluent into the environment. Organic water contaminants (OWCs), chemicals found in pharmaceutical drugs, detergents, surfactants, and other personal [...] Read more.

Conventional onsite wastewater treatment system design relies on a septic tank and soil treatment unit (STU) for treatment of wastewater and integration of the final effluent into the environment. Organic water contaminants (OWCs), chemicals found in pharmaceutical drugs, detergents, surfactants, and other personal care and cleaning products, have been observed in septic tank effluent and the environment. Sorption of OWC mass to soil is a key mechanism in the removal and retardation of many of these chemicals in effluent as it travels through an STU. The primary purpose of this study was to investigate the relationship between the fraction of organic carbon of soil and the equilibrium sorption partitioning coefficient of a selected group of relevant and diverse OWCs. A secondary goal is to evaluate current methods of modeling the sorption of selected OWCs in soil. Five point Freundlich isotherms were constructed from equilibrium sorption batch tests for target OWCs with four different soils. For soils with organic carbon fraction between 0.021 and 0.054, K_d values were calculated between 60 and 185 for 4-nonylphenol, 75 to 260 for triclosan, 115 to 270 for bisphenol-A, 3 to 255 for 17β-estradiol, 40 to 55 for 17α-ethynylestradiol, and 28 to 70 for estrone. An empirically derived, direct relationship between f_oc and K_d may be a useful approach to estimating sorption for a soil based on organic carbon content. Full article

(This article belongs to the Special Issue Advances in On-Site Wastewater Treatment and Technologies to Characterize the Fate and Transport of Wastewater Constituents)

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1090 KiB

Open AccessArticle

Transport of Pathogen Surrogates in Soil Treatment Units: Numerical Modeling

by Ivan Morales, Janet A. Atoyan, José A. Amador and Thomas Boving

Water 2014, 6(4), 818-838; https://doi.org/10.3390/w6040818 - 02 Apr 2014

Cited by 18 | Viewed by 7830

Abstract

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 [...] Read more.

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 >99.99% 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). Full article

(This article belongs to the Special Issue Advances in On-Site Wastewater Treatment and Technologies to Characterize the Fate and Transport of Wastewater Constituents)

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811 KiB

Open AccessArticle

Spatial Distribution of Fecal Indicator Bacteria in Groundwater beneath Two Large On-Site Wastewater Treatment Systems

by Charles Humphrey, Michael O'Driscoll and Jonathan Harris

Water 2014, 6(3), 602-619; https://doi.org/10.3390/w6030602 - 24 Mar 2014

Cited by 12 | Viewed by 7411

Abstract

On-site wastewater treatment systems (OWS) are a common means of wastewater treatment in coastal North Carolina, where the soils are sandy and groundwater is relatively close to the surface (<5 m). Wastewater contains elevated concentrations of pathogenic microorganisms that can contaminate groundwater and [...] Read more.

On-site wastewater treatment systems (OWS) are a common means of wastewater treatment in coastal North Carolina, where the soils are sandy and groundwater is relatively close to the surface (<5 m). Wastewater contains elevated concentrations of pathogenic microorganisms that can contaminate groundwater and surface water if OWS are not operating efficiently and distributing wastewater equally to all drainfield trenches. The objectives of this study were to compare the distribution of fecal indicator bacteria (FIB) in groundwater beneath a large low-pressure pipe (LPP) OWS and a large pump to distribution box system, and to determine the effectiveness of the systems in reducing FIB including total coliform, E. coli, and enterococci. Monitoring wells were installed at the fronts and ends of the drainfields for sample collection. Groundwater beneath the LPP had a more homogeneous spatial distribution of E. coli and enterococci concentrations and the specific conductivity of groundwater was also more uniform relative to groundwater beneath the distribution box system. Both systems were effective (>99%) at reducing FIB concentrations before discharge to groundwater. Results indicate that the LPP did enhance the distribution of FIB in groundwater beneath the drainfield area relative to the pump to distribution box system. Although the LPP system had a vadose zone over 2 m thinner than the pump to distribution box system, FIB treatment was similar. Enterococci was the most resilient FIB of the three tested. Full article

(This article belongs to the Special Issue Advances in On-Site Wastewater Treatment and Technologies to Characterize the Fate and Transport of Wastewater Constituents)

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887 KiB

Open AccessArticle

Performance of an Anaerobic Baffled Filter Reactor in the Treatment of Algae-Laden Water and the Contribution of Granular Sludge

by Yaqin Yu, Xiwu Lu and Yifeng Wu

Water 2014, 6(1), 122-138; https://doi.org/10.3390/w6010122 - 07 Jan 2014

Cited by 23 | Viewed by 8300

Abstract

This study investigated the performance and stability of an anaerobic baffled filter reactor in the treatment of algae-laden water from Taihu Lake at several organic loading rates. The study also evaluated the capability of soft filler to train granule sludge and improve the [...] Read more.

This study investigated the performance and stability of an anaerobic baffled filter reactor in the treatment of algae-laden water from Taihu Lake at several organic loading rates. The study also evaluated the capability of soft filler to train granule sludge and improve the anaerobic environment and sludge activity in the anaerobic baffled reactor (ABR), thereby enhancing the treatment efficiency. The ABR consisted of five rectangular compartments, each of which was 120 cm long, 80 cm wide, 80 cm high, and packed with soft filler. The anaerobic baffled filter reactor was found to be an efficient reactor configuration for the treatment of algae-laden water. The reactor was operated at an organic loading rate of 1.5 kg chemical oxygen demand (COD)/(m³d) and an ambient temperature of 30 °C; under these conditions, the COD removal efficiency was 80% and the biogas production rate was 293 mL/(Ld). Moreover, the soft filler increased the biomass retention time and decreased the rate at which solids were washed out from the reactor, promoting an improved spatial distribution of the microbial communities within the compartments. Methanoregula, Methanobacteriaceae, Methanosaeta, Methanoculleu, and Thermogymnomonas were the dominant archaeal species in each compartment during an operational period of approximately 100 days. The protease activity in the reactor decreased longitudinally down the reactor from Compartments 1 to 5, whereas the activity of coenzyme F₄₂₀ increased. The soft filler played a key role in successfully treating algae-laden water with the anaerobic baffled filter reactor. Full article

(This article belongs to the Special Issue Advances in On-Site Wastewater Treatment and Technologies to Characterize the Fate and Transport of Wastewater Constituents)

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524 KiB

Open AccessArticle

Monitoring Urban Wastewaters’ Characteristics by Visible and Short Wave Near-Infrared Spectroscopy

by Ignacio Melendez-Pastor, M. Belén Almendro-Candel, Jose Navarro-Pedreño, Ignacio Gómez, Mariano García Lillo and Encarni I. Hernández

Water 2013, 5(4), 2026-2036; https://doi.org/10.3390/w5042026 - 06 Dec 2013

Cited by 19 | Viewed by 6848

Abstract

On-line monitoring of wastewater parameters is a major scientific and technical challenge because of the great variability of wastewater characteristics and the extreme physical-chemical conditions that endure the sensors. Wastewater treatment plant managers require fast and reliable information about the input sewage and [...] Read more.

On-line monitoring of wastewater parameters is a major scientific and technical challenge because of the great variability of wastewater characteristics and the extreme physical-chemical conditions that endure the sensors. Wastewater treatment plant managers require fast and reliable information about the input sewage and the operation of the different treatment stages. There is a great need for the development of sensors for the continuous monitoring of wastewater parameters. In this sense, several optical systems have been evaluated. This article presents an experimental laboratory-based approach to quantify commonly employed urban wastewater parameters, namely biochemical oxygen demand in five days (BOD₅), chemical oxygen demand (COD), total suspended solids (TSS), and the ratio BOD₅:COD, with a visible and short wave near infrared (V/SW-NIR) spectrometer (400–1000 nm). Partial least square regression (PLSR) models were developed in order to quantify the wastewater parameters with the recorded spectra. PLSR models were developed for the full spectral range and also for the visible and near infrared spectral ranges separately. Good PLSR models were obtained with the visible spectral range for BOD₅ (RER = 9.64), COD (RER = 10.88), and with the full spectral range for the TSS (RER = 9.67). The results of this study show that V/SW-NIR spectroscopy is a suitable technique for on-line monitoring of wastewater parameters. Full article

(This article belongs to the Special Issue Advances in On-Site Wastewater Treatment and Technologies to Characterize the Fate and Transport of Wastewater Constituents)

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Review

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1141 KiB

Open AccessReview

The Effect of Influent Characteristics and Operational Conditions over the Performance and Microbial Community Structure of Partial Nitritation Reactors

by Alejandro Rodriguez-Sanchez, Alejandro Gonzalez-Martinez, Maria Victoria Martinez-Toledo, Maria Jesus Garcia-Ruiz, Francisco Osorio and Jesus Gonzalez-Lopez

Water 2014, 6(7), 1905-1924; https://doi.org/10.3390/w6071905 - 26 Jun 2014

Cited by 48 | Viewed by 9454

Abstract

Nitrogen is a main contaminant of wastewater worldwide. Novel processes for nitrogen removal have been developed over the last several decades. One of these is the partial nitritation process. This process includes the oxidation of ammonium to nitrite without the generation of nitrate. [...] Read more.

Nitrogen is a main contaminant of wastewater worldwide. Novel processes for nitrogen removal have been developed over the last several decades. One of these is the partial nitritation process. This process includes the oxidation of ammonium to nitrite without the generation of nitrate. The partial nitritation process has several advantages over traditional nitrification-denitrification processes for nitrogen removal from wastewaters. In addition, partial nitritation is required for anammox elimination of nitrogen from wastewater. Partial nitritation is affected by operational conditions and substances present in the influent, such as quinolone antibiotics. In this review, the impact that several operational conditions, such as temperature, pH, dissolved oxygen concentration, hydraulic retention time and solids retention time, have over the partial nitritation process is covered. The effect of quinolone antibiotics and other emerging contaminants are discussed. Finally, future perspectives for the partial nitritation process are commented upon. Full article

(This article belongs to the Special Issue Advances in On-Site Wastewater Treatment and Technologies to Characterize the Fate and Transport of Wastewater Constituents)

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