Promising Research and Strategies in Wastewater Treatment, Sludge Management and Valorization

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Environmental Sciences".

Deadline for manuscript submissions: closed (20 May 2023) | Viewed by 19843

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Special Issue Editors

Department of Chemical and Environmental Engineering, University of Oviedo, 33006 Oviedo, Spain
Interests: enzymatic hydrolysis; fungi; biological treatment; lignocellulosic biomass; cellulose; hemicellulose; lignin
Special Issues, Collections and Topics in MDPI journals
Catalysis, Reactors and Control Research Group (CRC), Department of Chemical and Environmental Engineering, University of Oviedo, 33006 Oviedo, Spain
Interests: emerging pollutants; adsorption process; electrochemical degradation; sludge valorization
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Rapid urbanization and industrialization, added to the presence of new pollutants, make it necessary to search for new wastewater treatment technologies that meet the high treatment capacity, as well as future water quality requirements.

Conventional WWTPs are designed primarily to remove organic matter and nutrients. For this reason, in same cases, these treatments are inefficient for the removal of some specific pollutants, with the consequent risk that this entails.  Furthermore, large amounts of sludge, derived from these processes, are produced every year, being considered the main residue from these plants. Their management requires important costs, both in economic and environmental terms, which makes it necessary to explore alternatives for their valorization. Waste reduction and reuse of wastewater seem to be an excellent option to meet the  concept of the circular economy in the wastewater treatment sector by reducing the environmental impacts. The topics of this Special Issue include but are not limited to the following:

  • Emerging pollutant removal by different technologies;
  • Microplastics as new emerging pollutants;
  • Novel technologies for wasterwater and sludge treatment;
  • Sludge valorization;
  • Wastewater reuse;
  • Environmental assessment of wastewater treatment.

Dr. Amanda Laca Pérez
Dr. Yolanda Patiño
Guest Editors

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Keywords

  • wastewater treatment
  • emerging pollutants
  • microplastics
  • sludge valorization
  • lifecycle assessment

Published Papers (9 papers)

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Editorial

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4 pages, 194 KiB  
Editorial
Special Issue on Promising Research and Strategies in Wastewater Treatment, Sludge Management, and Valorisation: Volume I
by Amanda Laca and Yolanda Patiño
Appl. Sci. 2023, 13(18), 10121; https://doi.org/10.3390/app131810121 - 08 Sep 2023
Viewed by 569
Abstract
Rapid urbanization and industrialization, together with new contaminants arising from many different sources, make it necessary to move forwards with research to face future challenges regarding water pollution [...] Full article

Research

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22 pages, 3435 KiB  
Article
Heterogeneous Fenton Oxidation with Natural Clay for Textile Levafix Dark Blue Dye Removal from Aqueous Effluent
by Manasik M. Nour, Maha A. Tony and Hossam A. Nabwey
Appl. Sci. 2023, 13(15), 8948; https://doi.org/10.3390/app13158948 - 03 Aug 2023
Cited by 4 | Viewed by 766
Abstract
The ever-increasing technological advancement and industrialization are leading to a massive discharge of hazardous waste into the aquatic environment, calling on scientists and researchers to introduce environmentally benign solutions. In this regard, the current work is based on introducing Fuller’s earth, which is [...] Read more.
The ever-increasing technological advancement and industrialization are leading to a massive discharge of hazardous waste into the aquatic environment, calling on scientists and researchers to introduce environmentally benign solutions. In this regard, the current work is based on introducing Fuller’s earth, which is regarded as an environmentally benign material, as an innovative Fenton oxidation technology to treat effluent loaded with Levafix Dark Blue dye. Initially, Fuller’s earth was chemically and thermally activated, then subjected to characterization using a field-emission scanning electron microscope (FE-SEM) augmented with an energy-dispersive X-ray analyzer (EDX) and Fourier transform infrared (FTIR). This detailed the morphologies of the samples and the functional groups on the catalyst leading to the reaction with the dye. Fuller’s earth, augmented with hydrogen peroxide, was then introduced as a photo-Fenton oxidation system under UV illumination for dye oxidation. Moreover, a response surface mythological analysis was applied to optimize the most effective operational parameters. The experimental data revealed that the optimal Fuller’s earth dose corresponded to 1.02 mg/L using the optimal H2O2 of 818 mg/L at pH 3.0, and the removal efficiency reached 99%. Moreover, the thermodynamic parameters were investigated, and the data revealed the positive ∆G′ and negative ∆S′ values that reflect the non-spontaneous nature of oxidation at high temperatures. Additionally, the negative ∆H′ values suggest the occurrence of the endothermic oxidation reaction. Furthermore, the reaction followed the second-order kinetic model. Finally, the catalyst stability was investigated, and reasonable removal efficiency was attained (73%) after the successive use of Fuller’s earth reached six cyclic uses. Full article
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14 pages, 2966 KiB  
Article
Preparation and Modification of Activated Carbon for the Removal of Pharmaceutical Compounds via Adsorption and Photodegradation Processes: A Comparative Study
by Brahim Samir, Nabil Bouazizi, Patrick Nkuigue Fotsing, Julie Cosme, Veronique Marquis, Guilherme Luiz Dotto, Franck Le Derf and Julien Vieillard
Appl. Sci. 2023, 13(14), 8074; https://doi.org/10.3390/app13148074 - 11 Jul 2023
Cited by 1 | Viewed by 900
Abstract
In the present research, the removal of pharmaceutical contaminants based on atenolol (AT) and propranolol (PR) using modified activated carbon (AC) in a liquid solution was studied. Two methods, adsorption and photodegradation, were used to eliminate AT and PR. First, AC was prepared [...] Read more.
In the present research, the removal of pharmaceutical contaminants based on atenolol (AT) and propranolol (PR) using modified activated carbon (AC) in a liquid solution was studied. Two methods, adsorption and photodegradation, were used to eliminate AT and PR. First, AC was prepared from date stems and then modified via hydroxylation (AC-OH) and impregnated into titanium dioxide (AC-TiO2) separately. The removal of AT and PR was investigated in terms of experimental parameters, such as pH, concentration, temperature, and the effectiveness of the processes. The results show that the removal of AT and PR reached 92% for the adsorption method, while 94% was registered for the photodegradation process. Likewise, in optimal experimental conditions, the adsorption of AT and PR over AC-OH showed good stability and recyclability, achieving five cycles without a visible decrease in the removal capacity. The results obtained in this work suggest that the low-cost and environmentally friendly synthesis of AC-OH is suitable to be considered for wastewater treatment at the industrial scale. Interestingly, the above results open a potential pathway to determine whether adsorption or photodegradation is more suitable for eliminating wastewater-related pharmaceutical pollutants. Accordingly, the experimental results recommend adsorption as a promising, durable, eco-friendly wastewater treatment method. Full article
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13 pages, 2345 KiB  
Article
Dose–Response Effect of Nitrogen on Microbial Community during Hydrocarbon Biodegradation in Simplified Model System
by Justyna Staninska-Pięta, Jakub Czarny, Wojciech Juzwa, Łukasz Wolko, Paweł Cyplik and Agnieszka Piotrowska-Cyplik
Appl. Sci. 2022, 12(12), 6012; https://doi.org/10.3390/app12126012 - 13 Jun 2022
Cited by 5 | Viewed by 1293
Abstract
Knowledge about the influence of C:N ratio on the biodegradation process of hydrocarbon compounds is of significant importance in the development of biostimulation techniques. The purpose of this study was to assess the impact of nitrogen compounds on the environmental consortium during the [...] Read more.
Knowledge about the influence of C:N ratio on the biodegradation process of hydrocarbon compounds is of significant importance in the development of biostimulation techniques. The purpose of this study was to assess the impact of nitrogen compounds on the environmental consortium during the process of biological decomposition of hydrocarbons. The experimental variants represented low, moderate, and excessive biostimulation with nitrogen compounds. The metabolic activity of the consortium was tested using the flow cytometry technique. The efficiency of the biodegradation of hydrocarbons of the consortium, based on the gas chromatography method, and metapopulation changes, based on the analysis of V4 16srRNA sequencing data, were assessed. The results of the research confirm the positive effect of properly optimized biostimulation with nitrogen compounds on the biological decomposition of polycyclic aromatic hydrocarbons. The negative impact of excessive biostimulation on the biodegradation efficiency and metabolic activity of microorganisms is also proven. Low resistance to changes in the supply of nitrogen compounds is demonstrated among the orders Xanthomonadales, Burkholderiales, Sphingomonadales, Flavobacteriales, and Sphingobacteriales. It is proven that quantitative analysis of the order of Rhizobiales, characterized by a high-predicted potential for the decomposition of polycyclic aromatic hydrocarbons, may be helpful during biostimulation optimization processes in areas with a high nitrogen deficiency. Full article
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19 pages, 3001 KiB  
Article
Removal of Emerging Contaminants as Diclofenac and Caffeine Using Activated Carbon Obtained from Argan Fruit Shells
by Badr Bouhcain, Daniela Carrillo-Peña, Fouad El Mansouri, Yassine Ez Zoubi, Raúl Mateos, Antonio Morán, José María Quiroga and Mohammed Hassani Zerrouk
Appl. Sci. 2022, 12(6), 2922; https://doi.org/10.3390/app12062922 - 12 Mar 2022
Cited by 12 | Viewed by 3406
Abstract
Activated carbons from argan nutshells were prepared by chemical activation using phosphoric acid H3PO4. This material was characterized by thermogravimetric analysis, infrared spectrometry, and the Brunauer–Emmett–Teller method. The adsorption of two emerging compounds, a stimulant caffeine and an anti-inflammatory [...] Read more.
Activated carbons from argan nutshells were prepared by chemical activation using phosphoric acid H3PO4. This material was characterized by thermogravimetric analysis, infrared spectrometry, and the Brunauer–Emmett–Teller method. The adsorption of two emerging compounds, a stimulant caffeine and an anti-inflammatory drug diclofenac, from distilled water through batch and dynamic tests was investigated. Batch mode experiments were conducted to assess the capacity of adsorption of caffeine and diclofenac from an aqueous solution using the carbon above. Adsorption tests showed that the equilibrium time is 60 and 90 min for diclofenac and caffeine, respectively. The adsorption of diclofenac and caffeine on activated carbon from argan nutshells is described by a pseudo-second-order kinetic model. The highest adsorption capacity determined by the mathematical model of Langmuir is about 126 mg/g for diclofenac and 210 mg/g for caffeine. The thermodynamic parameters attached to the studied absorbent/adsorbate system indicate that the adsorption process is spontaneous and exothermic for diclofenac and endothermic for caffeine. Full article
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17 pages, 2161 KiB  
Article
Long-Term Occurrence and Fate of Microplastics in WWTPs: A Case Study in Southwest Europe
by Andrea Menéndez-Manjón, Reyes Martínez-Díez, Daniel Sol, Amanda Laca, Adriana Laca, Amador Rancaño and Mario Díaz
Appl. Sci. 2022, 12(4), 2133; https://doi.org/10.3390/app12042133 - 18 Feb 2022
Cited by 20 | Viewed by 2488
Abstract
Microplastic (MP) water pollution is a major problem that the world is currently facing, and wastewater treatment plants (WWTPs) represent one of the main alternatives to reduce the MP release to the environment. Several studies have analysed punctual samples taken throughout the wastewater [...] Read more.
Microplastic (MP) water pollution is a major problem that the world is currently facing, and wastewater treatment plants (WWTPs) represent one of the main alternatives to reduce the MP release to the environment. Several studies have analysed punctual samples taken throughout the wastewater treatment line. However, there are few long-term studies on the evolution of MPs over time in WWTPs. This work analyses the performance of a WWTP sited in Southwest Europe in relation with annual occurrence and fate of MPs. Samples were monthly taken at different points of the facility (influent, secondary effluent, final effluent, and sludge) and MPs were quantified and characterised by means of stereomicroscopy and FTIR spectrophotometry. The majority of MPs found in wastewater and sludge samples were fragments and fibres. Regarding to the chemical composition, in the water samples, polyethylene (PE), polyethylene terephthalate (PET) and polypropylene (PP) stood out, whereas, in the sludge samples, the main polymers were PET, polyamide (PA) and polystyrene (PS). The MPs more easily removed during the wastewater treatment processes were those with sizes greater than 500 µm. Results showed that the MPs removal was very high during all the period analysed with removal efficiencies between 89% and 95%, so no great variations were found between months. MP concentrations in dry sludge samples ranged between 12 and 39 MPs/g, which represented around 79% of the total MPs removed during the wastewater treatment processes. It is noticeable that a trend between temperature and MPs entrapped in sewage sludge was observed, i.e., higher temperatures entailed higher percentage of retention. Full article
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11 pages, 1836 KiB  
Article
Biodegradation of Olive Mill Effluent by White-Rot Fungi
by Ana Isabel Díaz, Marta Ibañez, Adriana Laca and Mario Díaz
Appl. Sci. 2021, 11(21), 9930; https://doi.org/10.3390/app11219930 - 24 Oct 2021
Cited by 7 | Viewed by 2053
Abstract
The liquid fraction from the two-phase extraction process in the olive industry (alperujo), is a waste that contains lignocellulosic organic matter and phenolic compounds, difficult to treat by conventional biological methods. Lignocellulosic enzymes from white-rot fungi can be an interesting solution to break [...] Read more.
The liquid fraction from the two-phase extraction process in the olive industry (alperujo), is a waste that contains lignocellulosic organic matter and phenolic compounds, difficult to treat by conventional biological methods. Lignocellulosic enzymes from white-rot fungi can be an interesting solution to break down these recalcitrant compounds and advance the treatment of that waste. In the present work the ability of Phanerochaete chrysosporium to degrade the abovementioned liquid waste (AL) was studied. Experiments were carried out at 26 °C within the optimal pH range 4–6 for 10 days and with and without the addition of glucose, measuring the evolution of COD, BOD5, biodegradability index, reducing sugars, total phenolic compounds, and colour. The results obtained in this study revealed the interest of Phanerochaete chrysosporium for an economical and eco-friendly treatment of alperujo, achieving COD and colour removals around 60%, and 32% of total phenolic compounds degradation, regardless of glucose addition. Full article
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12 pages, 1561 KiB  
Article
Pharmaceutical and Antibiotic Pollutant Levels in Wastewater and the Waters of the Zarqa River, Jordan
by Makoto Shigei, Almoayied Assayed, Ayat Hazaymeh and Sahar S. Dalahmeh
Appl. Sci. 2021, 11(18), 8638; https://doi.org/10.3390/app11188638 - 17 Sep 2021
Cited by 17 | Viewed by 2519
Abstract
Assamra wastewater treatment plant (WWTP) is the largest treatment facility in Jordan. Treated wastewater is discharged into the Zarqa River (ZR) and used to irrigate fodder and vegetables. ZR also includes surface runoff, stormwater, and raw wastewater illegally discharged into the river. This [...] Read more.
Assamra wastewater treatment plant (WWTP) is the largest treatment facility in Jordan. Treated wastewater is discharged into the Zarqa River (ZR) and used to irrigate fodder and vegetables. ZR also includes surface runoff, stormwater, and raw wastewater illegally discharged into the river. This study examined pharmaceutically active compounds (PhAC) in water resources in the ZR basin. Samples of WWTP influent and effluent and river water from four sites along ZR were collected. Concentrations of 18 target antibiotics, one stimulant, and 15 other PhACs were determined in the samples. Five antibiotics were detected in WWTP influent (510–860 ng L−1 for ∑Antibiotics) and six in the effluent (2300–2600 ng L−1 for ∑Antibiotics). Concentrations in the effluent of all antibiotics except clarithromycin increased by 2- to 5-fold compared with those in influent, while clarithromycin concentration decreased by around 4- fold (from 308 to 82 ng L−1). WWTP influent and effluent samples contained 14 non-antibiotic PhACs, one simulant, and six antibiotics at detectable concentrations. The dominant PhACs were paracetamol (74% of ∑PhACs) in the influent and carbamazepine (78% of ∑PhACs) in the effluent. At ZR sampling sites, carbamazepine was the dominant PhAC in all cases (800–2700 ng L−1). The antibiotics detected in WWTP effluent were also detected at the ZR sites. In summary, water in ZR is contaminated with PhACs, including antibiotics, and wastewater discharge seems to be the main pathway for this contamination. The occurrence of antibiotics and other PhACs in the irrigated soil requires investigation to assess their fate. Full article
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Review

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17 pages, 971 KiB  
Review
Potential Use of Biochar in Pit Latrines as a Faecal Sludge Management Strategy to Reduce Water Resource Contaminations: A Review
by Matthew Mamera, Johan J. van Tol, Makhosazana P. Aghoghovwia, Alfredo B. J. C. Nhantumbo, Lydia M. Chabala, Armindo Cambule, Hendrix Chalwe, Jeronimo C. Mufume and Rogerio B. A. Rafael
Appl. Sci. 2021, 11(24), 11772; https://doi.org/10.3390/app112411772 - 13 Dec 2021
Cited by 8 | Viewed by 4703
Abstract
Faecal sludge management (FSM) in most developing countries is still insufficient. Sanitation challenges within the sub-Saharan region have led to recurring epidemics of water- and sanitation-related diseases. The use of pit latrines has been recognised as an option for on-site sanitation purposes. However, [...] Read more.
Faecal sludge management (FSM) in most developing countries is still insufficient. Sanitation challenges within the sub-Saharan region have led to recurring epidemics of water- and sanitation-related diseases. The use of pit latrines has been recognised as an option for on-site sanitation purposes. However, there is also concern that pit latrine leachates may cause harm to human and ecological health. Integrated approaches for improved access to water and sanitation through proper faecal sludge management are needed to address these issues. Biochar a carbon-rich adsorbent produced from any organic biomass when integrated with soil can potentially reduce contamination. The incorporation of biochar in FSM studies has numerous benefits in the control of prospective contaminants (i.e., heavy metals and inorganic and organic pollutants). This review paper evaluated the potential use of biochar in FSM. It was shown from the reviewed articles that biochar is a viable option for faecal sludge management because of its ability to bind contaminants. Challenges and possible sustainable ways to incorporate biochar in pit latrine sludge management were also illustrated. Biochar use as a low-cost adsorbent in wastewater contaminant mitigation can improve the quality of water resources. Biochar-amended sludge can also be repurposed as a useful economical by-product. Full article
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