Research

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16 pages, 466 KiB

Open AccessArticle

Sustainable and Innovative Solutions for Sewage Sludge Management

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Ludovico Spinosa

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Azize Ayol

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Jean-Christophe Baudez

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Water 2011, 3(2), 702-717; https://doi.org/10.3390/w3020702 - 22 Jun 2011

Cited by 92 | Viewed by 14383

Abstract

Sludge produced by municipal wastewater treatment plants (WWTPs) amounts to only a few percent by volume of the processed wastewater, but its handling accounts for up to 50% of total operating costs. Moreover, the need to achieve a sustainable sludge management strategy has [...] Read more.

Sludge produced by municipal wastewater treatment plants (WWTPs) amounts to only a few percent by volume of the processed wastewater, but its handling accounts for up to 50% of total operating costs. Moreover, the need to achieve a sustainable sludge management strategy has become of great concern. It follows that as conventional and more traditional options, such as land spreading for agricultural purposes, are progressively restricted, and often legally banned, the development of innovative systems to maximize the recovery of useful materials and/or energy is required. A change toward more sustainable procedures can be promoted through an integrated approach, including the assessment of management routes capable of maximizing the recycle/recovery benefits, through low energy impact systems, and the development of operational systems appropriate to local circumstances. Based on the above considerations, an integrated system is proposed in this paper. It includes Anaerobic digestion, Dewatering/Drying, and Pyrolysis/Gasification processes which are efficiently coupled for the recovery of products for material reuse and/or energy purposes. Such an integrated system should also allow the recovery of one or more materials, depending on the combination of processes which best fit specific local situations. Full article

(This article belongs to the Special Issue Science and Technology of Wastewater and Sludge Treatment)

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19 pages, 241 KiB

Open AccessArticle

Biosorption Parameter Estimation with Genetic Algorithm

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Water 2011, 3(1), 177-195; https://doi.org/10.3390/w3010177 - 16 Feb 2011

Cited by 14 | Viewed by 7668

Abstract

In biosorption research, a fairly broad range of mathematical models are used to correlate discrete data points obtained from batch equilibrium, batch kinetic or fixed bed breakthrough experiments. Most of these models are inherently nonlinear in their parameters. Some of the models have [...] Read more.

In biosorption research, a fairly broad range of mathematical models are used to correlate discrete data points obtained from batch equilibrium, batch kinetic or fixed bed breakthrough experiments. Most of these models are inherently nonlinear in their parameters. Some of the models have enjoyed widespread use, largely because they can be linearized to allow the estimation of parameters by least-squares linear regression. Selecting a model for data correlation appears to be dictated by the ease with which it can be linearized and not by other more important criteria such as parameter accuracy or theoretical relevance. As a result, models that cannot be linearized have enjoyed far less recognition because it is necessary to use a search algorithm for parameter estimation. In this study a real-coded genetic algorithm is applied as the search method to estimate equilibrium isotherm and kinetic parameters for batch biosorption as well as breakthrough parameters for fixed bed biosorption. The genetic algorithm is found to be a useful optimization tool, capable of accurately finding optimal parameter estimates. Its performance is compared with that of nonlinear and linear regression methods. Full article

(This article belongs to the Special Issue Science and Technology of Wastewater and Sludge Treatment)

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12 pages, 128 KiB

Open AccessArticle

The Effectiveness of Silica Sand in Semi-Aerobic Stabilized Landfill Leachate Treatment

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Mohammed J. K. Bashir

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Yung-Tse Hung

Water 2010, 2(4), 904-915; https://doi.org/10.3390/w2040904 - 06 Dec 2010

Cited by 25 | Viewed by 8478

Abstract

This study examines the suitability of natural silica sand as a low-cost adsorbent for the removal of ammoniacal nitrogen and heavy metals, particularly iron and zinc, from semi-aerobic stabilized landfill leachate. Leachate samples were collected from the Pulau Burung landfill site (PBLS) in [...] Read more.

This study examines the suitability of natural silica sand as a low-cost adsorbent for the removal of ammoniacal nitrogen and heavy metals, particularly iron and zinc, from semi-aerobic stabilized landfill leachate. Leachate samples were collected from the Pulau Burung landfill site (PBLS) in Penang, Malaysia. The above-mentioned contaminants are highlighted in this study because of their unsafe concentrations at PBLS. The effects of shaking time, settling time, and silica sand dosage on the study parameter removal efficiencies were investigated to predict the performance of the process. The adsorptions of ammoniacal nitrogen, iron, and zinc were judiciously described by Langmuir and Freundlich isotherm models. The optimum removal efficiencies of ammoniacal nitrogen, iron, and zinc obtained were 51%, 44.4%, and 39.2%, respectively, with a shaking time of 90 min, a settling time of 60 min, and with a dosage of 60 g (0.5 kg/L) of silica sand. Based on the coefficient of determination (R²) values obtained from Langmuir and Freundlich isotherm models, ammoniacal nitrogen, iron, and zinc adsorption were better fitted to the Freundlich model. Full article

(This article belongs to the Special Issue Science and Technology of Wastewater and Sludge Treatment)

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18 pages, 328 KiB

Open AccessArticle

Improvement of Hydraulic and Water Quality Renovation Functions by Intermittent Aeration of Soil Treatment Areas in Onsite Wastewater Treatment Systems

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Water 2010, 2(4), 886-903; https://doi.org/10.3390/w2040886 - 01 Dec 2010

Cited by 6 | Viewed by 7757

Abstract

We tested intermittent aeration of the soil treatment area (STA) of onsite wastewater treatment systems (OWTS) for its ability to restore and maintain STA hydraulic flow and improve the water quality functions of conventional OWTS. Evaluation was conducted on hydraulically-failed conventional OWTS at [...] Read more.

We tested intermittent aeration of the soil treatment area (STA) of onsite wastewater treatment systems (OWTS) for its ability to restore and maintain STA hydraulic flow and improve the water quality functions of conventional OWTS. Evaluation was conducted on hydraulically-failed conventional OWTS at three state-owned medical group homes in Washington County, RI, USA. Testing was conducted in two phases, with Phase I (before intermittent soil aeration (ISA)) comprising the first 6 months of the study, and Phase II (during ISA) the remaining 7 months. Intermittent soil aeration restored STA hydraulic function in all three systems despite a marked reduction in the STA total infiltrative surface. Soil pore water was collected from 30 and 90 cm below the STA during both phases and analyzed for standard wastewater parameters. Although the STA infiltrative surface was reduced—and the contaminant load per unit of area increased—after installation of the ISA system, no differences were observed between phases in concentration of total N, NO₃, total P, or dissolved organic carbon (DOC). Apparent removal rates—which do not account for dilution or differences in infiltrative area—for total N, total P, and DOC remained the same or improved during Phase II relative to the pre-operation phase. Furthermore, intermittent soil aeration enhanced actual removal rates —which do account for dilution and differences in infiltrative area. The effects of ISA on actual removal of contaminants from STE increased with increasing hydraulic load—a counterintuitive phenomenon, but one that has been previously observed in laboratory studies. The results of our study suggest that intermittent soil aeration can restore and maintain hydraulic flow in the STA and enhance carbon and nutrient removal in conventional OWTS. Full article

(This article belongs to the Special Issue Science and Technology of Wastewater and Sludge Treatment)

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Review

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26 pages, 297 KiB

Open AccessReview

Biofilm Fixed Film Systems

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Water 2011, 3(3), 843-868; https://doi.org/10.3390/w3030843 - 09 Sep 2011

Cited by 34 | Viewed by 10056

Abstract

The work reviewed here was published between 2008 and 2010 and describes research that involved aerobic and anoxic biofilm treatment of water pollutants. Biofilm denitrification systems are covered when appropriate. References catalogued here are divided on the basis of fundamental research area or [...] Read more.

The work reviewed here was published between 2008 and 2010 and describes research that involved aerobic and anoxic biofilm treatment of water pollutants. Biofilm denitrification systems are covered when appropriate. References catalogued here are divided on the basis of fundamental research area or reactor types. Fundamental research into biofilms is presented in two sections, Biofilm Measurement and Characterization and Growth and Modeling. The reactor types covered are: trickling filters, rotating biological contactors, fluidized bed bioreactors, submerged bed biofilm reactors, biological granular activated carbon, membrane bioreactors, and immobilized cell reactors. Innovative reactors, not easily classified, are then presented, followed by a section on biofilms on sand, soil and sediment. Full article

(This article belongs to the Special Issue Science and Technology of Wastewater and Sludge Treatment)

13 pages, 181 KiB

Open AccessReview

Activated Sludge and Other Aerobic Suspended Culture Processes

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Water 2011, 3(3), 806-818; https://doi.org/10.3390/w3030806 - 16 Aug 2011

Cited by 11 | Viewed by 7139

Abstract

A review of the literature published in 2008, 2009 and 2010 relating to activated sludge treatment of wastewater is presented. The review considers information on the topics of modeling and kinetics; process microbiology; nitrogen and phosphorus removal; treatment and effects of xenobiotics; oxygen [...] Read more.

A review of the literature published in 2008, 2009 and 2010 relating to activated sludge treatment of wastewater is presented. The review considers information on the topics of modeling and kinetics; process microbiology; nitrogen and phosphorus removal; treatment and effects of xenobiotics; oxygen transfer; and solids separation. Full article

(This article belongs to the Special Issue Science and Technology of Wastewater and Sludge Treatment)

20 pages, 303 KiB

Open AccessReview

Chemicals and Allied Products Waste Treatment

by

Yung-Tse Hung

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Erick Butler

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Ruth Yu-Li Yeh

Water 2011, 3(2), 629-648; https://doi.org/10.3390/w3020629 - 14 Jun 2011

Viewed by 6863

Abstract

A review of the literature published from 2008 to 2010 on topics related to chemicals and allied products is presented. The review considered several sections such as waste management, physicochemical treatment, aerobic treatment, anaerobic treatment, air emissions, soils and groundwater, and reuse. Full article

(This article belongs to the Special Issue Science and Technology of Wastewater and Sludge Treatment)

15 pages, 171 KiB

Open AccessReview

Liquid Radioactive Wastes Treatment: A Review

by

R. O. Abdel Rahman

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H. A. Ibrahium

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Yung-Tse Hung

Water 2011, 3(2), 551-565; https://doi.org/10.3390/w3020551 - 12 May 2011

Cited by 304 | Viewed by 23330

Abstract

Radioactive wastes are generated during nuclear fuel cycle operation, production and application of radioisotope in medicine, industry, research, and agriculture, and as a byproduct of natural resource exploitation, which includes mining and processing of ores, combustion of fossil fuels, or production of natural [...] Read more.

Radioactive wastes are generated during nuclear fuel cycle operation, production and application of radioisotope in medicine, industry, research, and agriculture, and as a byproduct of natural resource exploitation, which includes mining and processing of ores, combustion of fossil fuels, or production of natural gas and oil. To ensure the protection of human health and the environment from the hazard of these wastes, a planned integrated radioactive waste management practice should be applied. This work is directed to review recent published researches that are concerned with testing and application of different treatment options as a part of the integrated radioactive waste management practice. The main aim from this work is to highlight the scientific community interest in important problems that affect different treatment processes. This review is divided into the following sections: advances in conventional treatment of aqueous radioactive wastes, advances in conventional treatment of organic liquid wastes, and emerged technological options. Full article

(This article belongs to the Special Issue Science and Technology of Wastewater and Sludge Treatment)

31 pages, 405 KiB

Open AccessReview

Electrocoagulation in Wastewater Treatment

by

Erick Butler

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Yung-Tse Hung

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Ruth Yu-Li Yeh

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Mohammed Suleiman Al Ahmad

Water 2011, 3(2), 495-525; https://doi.org/10.3390/w3020495 - 06 Apr 2011

Cited by 176 | Viewed by 33414

Abstract

A review of the literature published in from 2008 to 2010 on topics related to electrochemical treatment within wastewater was presented. The review included several sections such as optimization, modeling, various wastewater treatment techniques, analytical and instrumentation, and comparison with other treatment methods. [...] Read more.

A review of the literature published in from 2008 to 2010 on topics related to electrochemical treatment within wastewater was presented. The review included several sections such as optimization, modeling, various wastewater treatment techniques, analytical and instrumentation, and comparison with other treatment methods. Full article

(This article belongs to the Special Issue Science and Technology of Wastewater and Sludge Treatment)

20 pages, 194 KiB

Open AccessReview

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Water 2011, 3(1), 157-176; https://doi.org/10.3390/w3010157 - 16 Feb 2011

Cited by 97 | Viewed by 13413

Abstract

Dye wastes represent one of the most problematic groups of pollutants because they can be easily identified by the human eye and are not easily biodegradable. This literature review paper highlights and provides an overview of dye waste treatments performed over the three [...] Read more.

Dye wastes represent one of the most problematic groups of pollutants because they can be easily identified by the human eye and are not easily biodegradable. This literature review paper highlights and provides an overview of dye waste treatments performed over the three years period from 2008–2010. Noteworthy processes for the treatment of dye waste include biological treatment, catalytic oxidation, filtration, sorption process and combination treatments. Full article

(This article belongs to the Special Issue Science and Technology of Wastewater and Sludge Treatment)

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