Editorial

6 pages, 208 KiB

Open AccessEditorial

Innovative Approaches for Drinking- and Waste-Water Treatment: An Editorial Review Summarizing and Assessing the Findings of the Special Issue

by Ioannis A. Katsoyiannis and Vincenzo Torretta

Appl. Sci. 2021, 11(5), 2063; https://doi.org/10.3390/app11052063 - 26 Feb 2021

Cited by 2 | Viewed by 1293

Abstract

The present special issue collected articles that address the very important topic of innovative approaches in water and wastewater treatment technologies. Thirteen articles are published, ten research paper and three review articles. The papers can be divided in four major categories, namely, membrane [...] Read more.

The present special issue collected articles that address the very important topic of innovative approaches in water and wastewater treatment technologies. Thirteen articles are published, ten research paper and three review articles. The papers can be divided in four major categories, namely, membrane treatment, adsorption studies, advanced oxidation processes and wastewater treatment optimization. In the editorial, a brief description of the findings of each paper is presented along with a critical assessment. Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

Research

Jump to: Editorial, Review

21 pages, 4697 KiB

Open AccessArticle

Effective Adsorption of Hexavalent Chromium and Divalent Nickel Ions from Water through Polyaniline, Iron Oxide, and Their Composites

by Amir Muhammad, Anwar ul Haq Ali Shah and Salma Bilal

Appl. Sci. 2020, 10(8), 2882; https://doi.org/10.3390/app10082882 - 21 Apr 2020

Cited by 31 | Viewed by 3557

Abstract

Water pollution caused by industrial wastes containing heavy metals and dyes is a major environmental problem. This study reports on the synthesis, characterization, and utilizations of Polyaniline (PANI) and its composites with Fe₃O₄ for the removal of hexavalent chromium Cr(VI) [...] Read more.

Water pollution caused by industrial wastes containing heavy metals and dyes is a major environmental problem. This study reports on the synthesis, characterization, and utilizations of Polyaniline (PANI) and its composites with Fe₃O₄ for the removal of hexavalent chromium Cr(VI) and divalent nickel Ni(II) ions from water. The adsorption data were fitted in Freudlich, Langmuir, Tempkin, Dubbanin–Ruddishkawich (D–R), and Elovich adsorption isotherms. The Freundlich isotherm fits more closely to the adsorption data with R² values of 0.9472, 0.9890, and 0.9684 for adsorption of Cr(VI) on Fe₃O₄, PANI, and PANI/Fe₃O₄ composites, respectively, while for adsorption of Ni(II) these values were 0.9366, 0.9232, and 0.9307 respectively. The effects of solution pH, initial concentration, contact time, ionic strength, and adsorbent dosage on adsorption behavior were investigated. The adsorption ability of composites was compared with pristine PANI and Fe₃O₄ particles. Activation energy and other thermodynamic properties such as changes in enthalpy, entropy, and Gibbs free energy indicated spontaneous and exothermic adsorption. Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

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10 pages, 926 KiB

Open AccessFeature PaperArticle

Cr(VI) Femoval from Ground Waters by Ferrous Iron Redox-Assisted Coagulation in a Continuous Treatment Unit Comprising a Plug Flow Pipe Reactor and Downflow Sand Filtration

by Ioannis A. Katsoyiannis, Maria Xanthopoulou and Anastasios I. Zouboulis

Appl. Sci. 2020, 10(3), 802; https://doi.org/10.3390/app10030802 - 23 Jan 2020

Cited by 11 | Viewed by 3129

Abstract

Chromium(VI) (Cr(VI)) is the main chromium species found in groundwater and is considered as a highly toxic and carcinogenic element to humans. In the present study, removal of Cr(VI) by coagulation with ferrous iron is studied in a continuous flow treatment unit comprising [...] Read more.

Chromium(VI) (Cr(VI)) is the main chromium species found in groundwater and is considered as a highly toxic and carcinogenic element to humans. In the present study, removal of Cr(VI) by coagulation with ferrous iron is studied in a continuous flow treatment unit comprising pipe flocculation reactors followed by a sand filter. The studied parameters, regarding their effect on the removal of hexavalent chromium, were the ferrous iron dose, the effect of linear velocity, and the effect of the starting Cr(VI) concentration. The experiments have shown that the Cr(VI) removal achieved was very efficient and residual Cr(VI) and total Cr concentration in the treated water was lower than 10 μg/L, provided that the required dose of ferrous iron is provided. In particular, the study demonstrated that the removal of hexavalent chromium, from initial concentration of 50 μg/L and 100 μg/L, was more than 90% with ferrous doses of 1 mg/L and 2 mg/L respectively, applying linear velocity of 8 m/h, at an initial pH value of 7.3. Iron concentration in treated water was very low, far below 200 μg/L, which is the limit for iron in drinking water. This unit comprises a simple treatment option, for applications at the household level, with minimum maintenance requirements capable of removing Cr(VI) to concentrations below 10 μg/L, which might be the future limit for chromium in drinking water. Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

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13 pages, 5005 KiB

Open AccessArticle

Preparation of Polyvinyl Alcohol/Bacterial-Cellulose-Coated Biochar–Nanosilver Antibacterial Composite Membranes

by Liang Zhang, Sen Zheng, Zhihui Hu, Lvling Zhong, Yao Wang, Xiaomin Zhang and Juanqin Xue

Appl. Sci. 2020, 10(3), 752; https://doi.org/10.3390/app10030752 - 21 Jan 2020

Cited by 19 | Viewed by 4008

Abstract

Pathogenic bacteria and microorganisms in drinking water can cause various diseases, and new types of antibacterial material for water treatment and filtration are urgently needed. In this work, polyvinyl alcohol/bacterial cellulose/biochar–nanosilver (PVA/BC/C-Ag) antibacterial composite membrane materials were prepared by uniformly dispersing C-Ag particles [...] Read more.

Pathogenic bacteria and microorganisms in drinking water can cause various diseases, and new types of antibacterial material for water treatment and filtration are urgently needed. In this work, polyvinyl alcohol/bacterial cellulose/biochar–nanosilver (PVA/BC/C-Ag) antibacterial composite membrane materials were prepared by uniformly dispersing C-Ag particles in a PVA/BC mixed gel. Fourier-transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), scanning electron microscopy (SEM), and thermogravimetric differential scanning calorimetry (TG-DSC) were used to characterize the composite membranes. Results indicated that the BC was uniformly mixed into the PVA gel and that the C-Ag particles were uniformly immobilized in the PVA/BC hybrid membrane. The PVA/BC/C-Ag composite membranes exhibited excellent antibacterial activity against Escherichia coli when assayed using a plate-counting technique. When used to treat actual contaminated water, the composite membranes demonstrated sustained antibacterial activity and good reusability. PVA/BC/C-Ag composite membranes have great potential for the development of drinking water treatment applications. Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

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18 pages, 3511 KiB

Open AccessArticle

Source Apportionment and Health Risk Assessment of Heavy Metals in Eastern Guangdong Municipal Solid Waste

by Zhihua Tang, Minru Liu, Linzi Yi, Huafang Guo, Tingping Ouyang, Hua Yin and Mingkun Li

Appl. Sci. 2019, 9(22), 4755; https://doi.org/10.3390/app9224755 - 07 Nov 2019

Cited by 8 | Viewed by 2020

Abstract

This research focused on the contents of the five most bio-toxic heavy metals, As, Cd, Hg, Cr, and Pb of 26 municipal solid waste (MSW) samples from the Eastern Guangdong Area. To investigate the apportion of the heavy metal source, Pearson correlation and [...] Read more.

This research focused on the contents of the five most bio-toxic heavy metals, As, Cd, Hg, Cr, and Pb of 26 municipal solid waste (MSW) samples from the Eastern Guangdong Area. To investigate the apportion of the heavy metal source, Pearson correlation and principal component analysis (PCA) were introduced as major approaches. The health risks posed to MSW workers exposed to heavy metals in MSW were assessed using a Monte Carlo simulation combined with the US Environmental Protection Agency Health Risk Assessment Model. The As, Cd, Hg, Cr, and Pb contents of the east Guangdong MSW were (0.76 ± 0.75), (2.14 ± 4.44), (0.11 ± 0.14), (55.42 ± 31.88), and (30.67 ± 20.58) mg/kg, respectively. Hg, Cr, and Pb were potentially derived from glass, textile, food waste, and white plastic, while As and Cd were mainly derived from soil and food waste in the MSW. The non-carcinogenic risks of heavy metal in MSW exposure to MSW workers could be ignored. However, the heavy metals in MSW might pose carcinogenic risks, with the probabilities for male and female workers being 35% and 45%, respectively. The non-carcinogenic and carcinogenic risk indices were slightly higher for female workers under the same exposure situations. Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

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15 pages, 1746 KiB

Open AccessFeature PaperArticle

Improving SBR Performance Alongside with Cost Reduction through Optimizing Biological Processes and Dissolved Oxygen Concentration Trajectory

by Robert Piotrowski, Aleksander Paul and Mateusz Lewandowski

Appl. Sci. 2019, 9(11), 2268; https://doi.org/10.3390/app9112268 - 31 May 2019

Cited by 22 | Viewed by 4785

Abstract

Authors of this paper take under investigation the optimization of biological processes during the wastewater treatment in sequencing batch reactor (SBR) plant. A designed optimizing supervisory controller generates the dissolved oxygen (DO) trajectory for the lower level parts of the hierarchical control system. [...] Read more.

Authors of this paper take under investigation the optimization of biological processes during the wastewater treatment in sequencing batch reactor (SBR) plant. A designed optimizing supervisory controller generates the dissolved oxygen (DO) trajectory for the lower level parts of the hierarchical control system. Proper adjustment of this element has an essential impact on the efficiency of the wastewater treatment process as well as on the costs generated by the plant, especially by the aeration system. The main goal of the presented solution is to reduce the plant energy consumption and to maintain the quality of effluent in compliance with the water-law permit. Since the optimization is nonlinear and includes variations of different types of variables, to solve the given problem the authors performed simulation tests and decided to implement a hybrid of two different optimization algorithms: artificial bee colony (ABC) and direct search algorithm (DSA). Simulation tests for the wastewater treatment plant case study are presented. Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

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15 pages, 6079 KiB

Open AccessFeature PaperArticle

Comparative Performance of Catalytic Fenton Oxidation with Zero-Valent Iron (Fe(0)) in Comparison with Ferrous Sulphate for the Removal of Micropollutants

by Anuradha Goswami and Jia-Qian Jiang

Appl. Sci. 2019, 9(11), 2181; https://doi.org/10.3390/app9112181 - 28 May 2019

Cited by 13 | Viewed by 3287

Abstract

This research aims to depict the comparative performance of micropollutants’ removal by FeSO₄- and zero-valent iron (Fe(0))-catalytic Fenton oxidation and to explore the possibilities of minimising the sludge production from the process. The emerging micropollutants used for the study were gabapentin, [...] Read more.

This research aims to depict the comparative performance of micropollutants’ removal by FeSO₄- and zero-valent iron (Fe(0))-catalytic Fenton oxidation and to explore the possibilities of minimising the sludge production from the process. The emerging micropollutants used for the study were gabapentin, sulfamethoxazole, diuron, terbutryn and terbuthylazine. The Taguchi method, which evaluates the signal-to-noise ratio instead of the standard deviation, was used to develop robust experimental conditions. Though both FeSO₄- and Fe(0)-catalytic Fenton oxidation were able to completely degrade the stated micropollutants, the Fe(0)-catalytic Fenton process delivered better removal of dissolved organic carbon (DOC; 70%) than FeSO₄ catalytic Fenton oxidation (45%). Fe(0)-catalytic Fenton oxidation facilitated heterogeneous treatment functions, which eliminated toxicity from contaminated solution and there was no recognisable sludge production. Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

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18 pages, 6098 KiB

Open AccessFeature PaperArticle

Reactive Black 5 Degradation on Manganese Oxides Supported on Sodium Hydroxide Modified Graphene Oxide

by Hayarpi Saroyan, Dimitra Ntagiou, Kyriazis Rekos and Eleni Deliyanni

Appl. Sci. 2019, 9(10), 2167; https://doi.org/10.3390/app9102167 - 27 May 2019

Cited by 21 | Viewed by 4112

Abstract

Sodium hydroxide-modified graphene oxide was used as manganese oxides support for the preparation of nanocomposites via a one-pot preparation route for the degradation of Reactive Black 5. The nanocomposites were characterized for their structure by X-ray diffraction, for their textural properties by Nitrogen [...] Read more.

Sodium hydroxide-modified graphene oxide was used as manganese oxides support for the preparation of nanocomposites via a one-pot preparation route for the degradation of Reactive Black 5. The nanocomposites were characterized for their structure by X-ray diffraction, for their textural properties by Nitrogen adsorption, and for their surface chemistry by Fourier transform infrared spectroscopy, potentiometric titration, and thermal analysis measurements. The nanocomposites prepared showed to possess high activity for the degradation/oxidation of Reactive Black 5 at ambient conditions, without light irradiation, which was higher than that of the precursors manganese oxides and can be attributed to the synergistic effect of the manganese oxides and the modified graphene oxide. Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

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13 pages, 1253 KiB

Open AccessArticle

Performance Evaluation of Pilot-scale Hybrid Anaerobic Baffled Reactor (HABR) to Process Dyeing Wastewater Based on Grey Relational Analysis

by Zhixin Qi, Guoli Xiang and Deqi Xiong

Appl. Sci. 2019, 9(10), 1974; https://doi.org/10.3390/app9101974 - 14 May 2019

Cited by 12 | Viewed by 3257

Abstract

A pilot-scale six-compartment hybrid anaerobic baffled reactor (HABR) with effective volume of 18 m³ was used to treat dyeing wastewater. The HABR system was able to treat the wastewater efficiently after FeSO₄ pretreatment, as indicated by removal efficiencies of 33.7% for [...] Read more.

A pilot-scale six-compartment hybrid anaerobic baffled reactor (HABR) with effective volume of 18 m³ was used to treat dyeing wastewater. The HABR system was able to treat the wastewater efficiently after FeSO₄ pretreatment, as indicated by removal efficiencies of 33.7% for chemical oxygen demand (COD), 39.9% for suspended solid (SS), and 22.5% for sulfate (SO₄²⁻) during steadily operational period. Gas chromatography–mass spectrometry (GC-MS) showed that the concentrations of alkanes, amides, organic acids, ketones, phenols, and esters were much lower in the effluent than those in the influent; many high-molecular-weight compounds such as cyclanes, quinolines, and phenols were successfully transformed to low-molecular-weight ones. As illustrated from the results of generalized grey relational analysis (GGRA), COD removal efficiency was more closely associated with flow rate, organic loading rate (OLR), water temperature, and influent SS among the whole selected possible factors. Based on the overall treating effectiveness and the GGRA study, the optimized operation strategy of the dyeing wastewater treatment by HABR was obtained as the hydraulic retention time (HRT) of 12 h for steady-state operation with an up-flow velocity of 1.7 m/h as well as OLR of 1.5–2.0 kg COD/(m³·d). Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

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12 pages, 3375 KiB

Open AccessArticle

Graphene Oxide Adsorption Enhanced by Attapulgite to Remove Pb (II) from Aqueous Solution

by Bigui Wei, Xiabing Cheng, Gang Wang, Hua Li, Xiaosan Song and Liang Dai

Appl. Sci. 2019, 9(7), 1390; https://doi.org/10.3390/app9071390 - 02 Apr 2019

Cited by 13 | Viewed by 2546

Abstract

To improve the adsorption and separation efficiency of lead-containing wastewater by graphene oxide (GO), attapulgite (ATP) was used through a simple hydrothermal reaction. The prepared GO was characterized by SEM, TEM, FTIR, and XPS. The adsorption properties of the prepared GO were investigated. [...] Read more.

To improve the adsorption and separation efficiency of lead-containing wastewater by graphene oxide (GO), attapulgite (ATP) was used through a simple hydrothermal reaction. The prepared GO was characterized by SEM, TEM, FTIR, and XPS. The adsorption properties of the prepared GO were investigated. The maximum adsorption capacity of Pb²⁺ on as-prepared GO at pH 5 and 25 °C was 450.9 mg/g. It is concluded that the as-prepared GO can be used as a high-efficiency adsorbent for lead-containing wastewater. Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

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14 pages, 2920 KiB

Open AccessArticle

Adsorption of Arsenic and Heavy Metals from Solutions by Unmodified Iron-Ore Sludge

by Khai M. Nguyen, Bien Q. Nguyen, Hai T. Nguyen and Ha T.H. Nguyen

Appl. Sci. 2019, 9(4), 619; https://doi.org/10.3390/app9040619 - 13 Feb 2019

Cited by 36 | Viewed by 4428

Abstract

Arsenic and heavy-metal-contaminated environments are a major concern due to their negative impacts on exposed people and ecosystems. In this study, sludge from an iron-ore processing area was used as an adsorbent to remove As, Mn, Zn, Cd, and Pb from aqueous solutions. [...] Read more.

Arsenic and heavy-metal-contaminated environments are a major concern due to their negative impacts on exposed people and ecosystems. In this study, sludge from an iron-ore processing area was used as an adsorbent to remove As, Mn, Zn, Cd, and Pb from aqueous solutions. The adsorption capacity of target adsorbates was investigated in batch experiments of both single- and mixed-metal solutions. The batch studies show that the maximum Langmuir adsorption capacities of the heavy metals onto the adsorbent occurred in the order Pb > As > Cd > Zn > Mn, and ranged from 0.710 mg/g to 1.113 mg/g in the single-metal solutions and from 0.370 mg/g to 1.059 mg/g in the mixed-metal solutions. The results of the kinetic experiments are consistent with pseudo-first-order and pseudo-second-order models, with a slightly better fit to the latter. Adsorption performances indicate that iron-ore sludge can simultaneously adsorb multiple metal ions and is a promising adsorbent for the removal of toxic pollutants from water. Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

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Review

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18 pages, 295 KiB

Open AccessFeature PaperReview

Removal of Arsenic, Chromium and Uranium from Water Sources by Novel Nanostructured Materials Including Graphene-Based Modified Adsorbents: A Mini Review of Recent Developments

by Athanasia K. Tolkou, Ioannis A. Katsoyiannis and Anastasios I. Zouboulis

Appl. Sci. 2020, 10(9), 3241; https://doi.org/10.3390/app10093241 - 07 May 2020

Cited by 37 | Viewed by 3916

Abstract

Groundwater is commonly used as a drinking water resource all over the world. Therefore, groundwater contamination by toxic metals is an important issue of utmost concern for public health, and several technologies are applied for their effective removal, such as coagulation, ion exchange, [...] Read more.

Groundwater is commonly used as a drinking water resource all over the world. Therefore, groundwater contamination by toxic metals is an important issue of utmost concern for public health, and several technologies are applied for their effective removal, such as coagulation, ion exchange, adsorption, and membrane applications like reverse osmosis. Adsorption is acknowledged as a simple, effective and economic technology, which has received increased interest recently, despite certain limitations regarding operational applications. The respective scientific efforts have been specifically focused on the development and implementation of novel nano-structured adsorbent materials, which may offer extensive specific surface areas, much higher than the conventional adsorbents, and hence, are expected to present higher removal efficiencies of pollutants. In this paper, the recent developments of nanomaterial applications for arsenic, chromium and uranium removal from groundwaters are critically reviewed. Particularly, the use of novel composite materials, based mainly on hybrid metallic oxide nanoparticles and on composites based on graphene oxide (GO) (i.e., graphene-based hybrids), showed promising evidences to achieve efficient removal of toxic metals from water sources, even in full scale applications. Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

25 pages, 946 KiB

Open AccessReview

Application and Evaluation of Energy Conservation Technologies in Wastewater Treatment Plants

by Yongteng Sun, Ming Lu, Yongjun Sun, Zuguo Chen, Hao Duan and Duan Liu

Appl. Sci. 2019, 9(21), 4501; https://doi.org/10.3390/app9214501 - 24 Oct 2019

Cited by 11 | Viewed by 8409

Abstract

High energy consumption is an important issue affecting the operation and development of wastewater treatment plants (WWTPs). This paper seeks energy-saving opportunities from three aspects: energy application, process optimization, and performance evaluation. Moreover, effective energy-saving can be achieved from the perspective of energy [...] Read more.

High energy consumption is an important issue affecting the operation and development of wastewater treatment plants (WWTPs). This paper seeks energy-saving opportunities from three aspects: energy application, process optimization, and performance evaluation. Moreover, effective energy-saving can be achieved from the perspective of energy supply and recovery by using green energy technologies, including wastewater and sludge energy recovery technologies. System optimization and control is used to reduce unnecessary energy consumption in operation. Reasonable indexes and methods can help researchers evaluate the application value of energy-saving technology. Some demonstration WWTPs even can achieve energy self-sufficiency by using these energy conservation technologies. Besides, this paper introduces the challenges faced by the wastewater treatment industry and some emerging energy-saving technologies. The work can give engineers some suggestions about reducing energy consumption from comprehensive perspectives. Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

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24 pages, 5202 KiB

Open AccessFeature PaperReview

What Advanced Treatments Can Be Used to Minimize the Production of Sewage Sludge in WWTPs?

by Maria Cristina Collivignarelli, Alessandro Abbà, Marco Carnevale Miino and Vincenzo Torretta

Appl. Sci. 2019, 9(13), 2650; https://doi.org/10.3390/app9132650 - 29 Jun 2019

Cited by 79 | Viewed by 7388

Abstract

Similar to other types of waste, sewage sludge (SS) must be minimized, not only to respect the European Directive 2018/851 on waste, but also because the cost of sludge management is approximately 50% of the total running costs of a wastewater treatment plant [...] Read more.

Similar to other types of waste, sewage sludge (SS) must be minimized, not only to respect the European Directive 2018/851 on waste, but also because the cost of sludge management is approximately 50% of the total running costs of a wastewater treatment plant (WWTP). Usually, minimization technologies can involve sewage sludge production with three different strategies: (i) adopting a process in the water line that reduces the production of sludge; (ii) reducing the water content (dewatering processes) or (iii) reducing the fraction of volatile solids (stabilization). This review, based on more than 130 papers, aims to provide essential information on the process, such as the advantages, the drawbacks and the results of their application. Moreover, significant information on the technologies still under development is provided. Finally, this review reports a discussion on the impact of the application of the proposed processes in the sludge line on a WWTP with a capacity exceeding 100,000 population equivalent (PE). Full article

(This article belongs to the Special Issue Innovative Approaches for Drinking- and Waste-Water Treatment)

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