Wastewater Recycling Research Articles

Recycling of wheat gluten wastewater: Recovery of arabinoxylan and application of its film in cherry and strawberry preservation

This study investigated the effect of an edible water-extractable arabinoxylan (WEAX) coating on the postharvest preservation of strawberries and cherries. The WEAX film was prepared using carboxymethyl chitosan (CMCS) film as a control, with thorough characterization of its film properties. Subsequently, strawberry and cherry fruits were submerged in a solution containing edible film-forming materials and left to be stored at room temperature, followed by the analysis of their physicochemical parameters to assess their preservation efficacy. The results show that the WEAX film exhibited enhanced flexibility, superior water vapor permeability, thermal stability, and surface morphology. Furthermore, the implementation of WEAX film effectively mitigated weight loss, decay, color degradation, softening process, ascorbic acid decline, anthocyanin accumulation, and an increase in malondialdehyde content in fruits. Thus, the incorporation of WEAX coating demonstrates its capability in prolonging the shelf life of fruits post-harvest, underscoring its potential in fruit preservation practices.

Carbon composites as an Avante garde material in mitigating dyes and heavy metal pollution

Abstract Depletion of potable water availability is threatening the whole biota, owing to the presence of anthropogenic compounds and hazardous chemicals above the permissible levels. Although many conventional methods exist, the development of innovative technologies is critical for wastewater treatment and recycling. Carbon composites have recently seen widespread use across a variety of industries due to their distinctive and superior properties. These carbon composites are easily integrated into many stages of the treatment process, making them efficient, cost-effective, and environmentally friendly. This chapter discusses the importance and effectiveness of carbon-based composite materials in removing toxic dyes and heavy metal contaminants from the environment. Carbon composites are classified according to their sources, preparation methods, and applications. This chapter also discusses various research perspectives on carbon composites, particularly from an environmental and financial standpoint.

Adopting sea water reverse osmosis desalination technologies for sustainable development: lessons learnt from Algiers Science and Technology for membranes 2023 workshop

The city of Algiers hosted the workshop on Science and Technology for Membranes from 30th May to 1st June 2023—STM 2023, held in Algeria. The main topics focused on Reverse Osmosis (RO) desalination technologies, decentralized autonomous systems, wastewater recycling for circularity, and the effects of green membrane processes on socio-economic growth. This review examines the influence of global trends and instabilities (i.e., climate change, disrupted supply chain platforms, natural disasters) on the steady supply of freshwater. The implementation of RO desalination solutions and their sustainability are assessed based on resiliency factors, which is helpful to screen water treatment alternatives based on technological benefits, ecological safety and environmental protection. Key takeaways from this study call for rolling out local membrane production capabilities, promoting the benefits of autonomous decentralized treatment systems, prioritizing innovative solutions to reduce greenhouse gas emissions, and for developing RO-specific equipment recycling infrastructures. Implementing these new tactics can lead to mitigate water scarcity and enable a sustainable deployment of desalination membrane technologies in Algeria and its region.

Modelling effluent reuse in the pulp and paper industry to predict consequences on conductivity.

The objective of this study was to assess, through simulation, conductivity variations in pulp and paper circuits when recycling waste water treatment plant (WWTP) effluent with a view to reducing fresh water use in a tissue mill. WWTP effluent was recycled in the process for different uses. A PS2000 digital model coupled with the PHREEQC chemical simulation engine was used to identify and quantify the main sources of conductivity: caustic soda, sodium bisulphite and acetate production through anaerobic microbial activity. Recycling WWTP effluent enables fresh water uptake to be reduced by 50% when used for pulp dilution or white water, by 81% when used in paper machine showers, and up to 96% for all uses combined. As fresh water use decreases, circuit closure increases along with, consequently, COD and conductivity. COD build-up can be controlled by best available techniques application. Recycling WWTP effluent has a strong impact on conductivity. However, the impact of high conductivity levels on additives performance is limited in the case of the mill studied. Acetate concentration could be controlled by better agitation of tanks or the introduction of air by pumps. Furthermore, limiting acetate production can reduce the need for caustic soda to control the pH.

Structure optimization of ceramic-based metal−organic framework membrane for efficient desalination

To address global water pollution and crisis issue, wastewater recycling, seawater and brackish water desalination have been increasingly utilized to produce clean water. Ceramic membranes have been gaining widespread interest due to their unique physicochemical properties and high stability. Integrating nanoporous MOF (metal organic framework) with ceramic membranes could enable a rational design of ceramic-based MOF membranes with enhance sieving performance. Herein, we report an in-situ method to construct an inter-crystalline defect-free MOF layer on ZrO2 ceramic membranes for efficient desalination application. After optimizing synthesis parameters, an inter-crystalline defect-free and well-intergrown ceramic-based MOF membrane was obtained. The ceramic-based MOF membranes not only demonstrated a near-complete salt rejection, but also exhibited high water flux, which are superior to most of the reported zeolite and MOF membranes. In addition, the MOF membranes exhibited promising performance and structure stability even when exposed to harsh water environments. Our work introduces a protocol for the design of high-performance ceramic-based MOF membrane as a promising candidate for challenging desalination applications under different environments.

Reliability of using secondary and tertiary treated wastewater in concrete mixing and curing

AbstractWater scarcity is a problem that faces many regions. In a developing and arid countries, the need for fresh water is exponentially increasing. One of the most water consuming industries is the construction industry, especially in concrete manufacturing. This research is an evaluation of the Reliability of recycled wastewater to be used in concrete manufacturing. Two different wastewater treatment regimens are implemented: secondary and tertiary treated wastewater. The treated wastewater, either secondary or tertiary, replaces potable water with percentages of 25%, 50%, and 100%. The mixture of the two types of water is used in concrete mixing and curing. Control specimens with pure potable water are cast for the comparison. The experimental program investigated the cement setting, and for fresh concrete slump test is performed on all concrete mixtures. The hardened concrete is tested in compression and flexural strengths at ages of 7 days, 28 days, and 90 days. To investigate concrete durability, permeability test is conducted in addition to sulfate attack resistance. The concrete chemical composition is compared using the X-Ray Defragmentation (XRD) test. The results show that the treated wastewater may delay both the initial and final setting. The phenomenon is more pronounced in secondary treated wastewater. No significant effect on concrete performance in the fresh state is detected. For the compressive strength, both treatment regimens can be safely used. However, the flexural strength is reduced at the late ages. Using treated wastewater affects the permeability of concrete to be more durable and protect the reinforcement steel from rusting. For the XRD test, the results show different intensities and positions of the peaks of the different compounds encountered in the treated wastewater. Under sulfate attach, the treated wastewater specimens give higher expansion compared with potable water. In conclusion secondary and tertiary treated wastewater can be used in concrete mixing and curing. However, the manufactured concrete should be protected from sulfate attack to avoid excessive expansion.

Fenton and electro-Fenton treatment for industrial textile wastewater recycling. Comparison of by-products removal, biodegradability, toxicity, and re-dyeing

A comparative study of the results obtained from using Fenton and electro-Fenton processes in textile wastewater treatment is presented. Global indicators, color, COD, TOC, and BOD5 were employed to investigate the treatments. Examination of the representative by-products gave new insights into Fenton. Even though the color removal was higher for classical Fenton (almost 100% color removal) than for electro-Fenton, the overall purification effect was not directly advantageous for Fenton. We found that electro-Fenton removed COD and TOC more efficiently. The biodegradability BI (BOD5/COD) parameter was investigated, where the textile wastewater was hardly biodegradable (BI was 0.12 ± 0.007). BI of Fenton was also low (0.044 ± 0.006). Electro-Fenton yielded a considerably more promising result, where BI was 0.83 ± 0.15, and proved more bio-friendly than classical Fenton. Additionally, electro-Fenton was more efficient in by-product removal, especially the naphthalic component, with 90% removal (while Fenton removed 50%). The by-products influenced the after-treatment toxicity assessment of V. fischeri. The EC50 values were below 2% and even lower for electro-Fenton. The results of the color matching parameters (DECMC) of re-dyeing were unacceptable using after-Fenton water at 8.66. DECMC results were between 1.01 and 2.71 after electro-Fenton treatment and had a recycling perspective.

Inorganic ion accumulation model in wastewater recycling systems: Printing and dyeing case

To solve the problem of inorganic ion accumulation in the recycling process of printing and dyeing wastewater, a mathematical model based on cycle-index and removal efficiency was proposed. The model's capacity to describe the ion accumulation was essentially confirmed through simulation and pilot tests. Results indicated that this model can better predict total dissolved solids (TDS), although the prediction results for specific ions require further refinement. With fewer than 60 cycles, TDS in the pilot system could be reliably predicted. Sensitivity analysis revealed that, when TDS, SO42−, Fe, and Mn in the effluent were considered control targets, the number of cycles, water flow, total inorganic salts added, and the recycling efficiency of printing and dyeing wastewater significantly influenced the prediction equation.

Role of public attitude, knowledge, and trust in shaping the acceptance of recycled wastewater for potable and non-potable uses

Abstract The acceptance of recycled wastewater plays a pivotal role in shaping the success of water management strategies. This study examines relation of public attitudes, knowledge, behaviors, and trust toward recycled wastewater systems, utilizing a survey of participants. The results reveal substantial knowledge deficits, with only 23.8% correctly defining recycled wastewater. In addition, 46.3% of respondents were knowledgeable about water scarcity, while 45.3% correctly identified the largest water uses. Attitudes were more reserved toward potable applications, with only 5% strongly agreeing to consume recycled water for drinking. Behavioral intentions favored non-potable uses, with 87% agreeing to use recycled wastewater for home gardening and flushing toilets, while 56% considered consuming food irrigated with recycled wastewater acceptable. Trust in water authorities emerged as a significant factor influencing acceptance. Lack of competence and not acting in public interest were identified as key factors eroding trust. The study also explored the influence of religion, revealing that non-contact applications were widely accepted across all religions, while direct-contact applications generated varied responses. The findings underscore the need for targeted educational campaigns, the cultivation of trust, and a nuanced approach considering cultural and religious diversity to promote wastewater recycling.

Anti-fouling graphene oxide membranes intercalated with Co-anchored graphitic carbon nitride nanosheet for enhanced water purification

Membrane separation technology has been widely used in wastewater recycling. Graphene oxide (GO) membranes have been widely developed, but membrane fouling is still a serious challenge. Here, GO-based membranes intercalated with Co-anchored graphitic carbon nitride nanosheet (Co@CNN) were prepared by a vacuum-filtrated assembly strategy. The resulting GO/Co@CNN membrane with an appropriate interlayer d-spacing (0.81 nm) and loading yield (0.30 ± 0.03 mg/cm2) can effectively separate methyl blue (MB) with a flux of 66.9 ± 2.7 L m-2h−1 under 1 bar, although the membrane has been fouled due to the adsorption of MB on the sample. Co@CNN can activate potassium peroxymonosulfat (PMS) to generate multiple active free radicals for the oxidation of MB via an advanced oxidation process (AOP). Therefore, the fouled membrane renews and can be employed to deal with wastewater repeatedly.

Sustainable activation of sisal fiber-reinforced slag composites: Mechanical strength and microstructural insights through recycling of alkali-treated wastewaters

An alkali treatment is necessary for natural plant fibers employed as reinforcing additives in inorganic cementitious materials, aiming to diminish moisture sensitivity and facilitate interlocking between the matrix and additives. Recycling alkali-treated fiber wastewaters (ATFWs) is crucial to prevent significant environmental pollution. Sisal fiber (SF)-reinforced alkali-activated slag-based composites incorporating ATFWs were prepared and compared to the control, aiming to investigate the effects of alkali-treated SFs and recycled ATFWs on the long-term mechanical properties and microstructures. Initially, the influence of the treated duration of SFs was examined on the electrical conductivity (EC) of ATFWs. Subsequently, the effects of SFs and ATFWs on the 28-day and 360-day flexural and compressive strengths were investigated, including an observation of failure modes. Furthermore, the effect mechanism of ATFWs in SF-reinforced composites was detected concerning morphology, microstructure, and composition by using diverse analytical techniques such as Scanning Electron Microscopy (SEM), Energy-Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Thermogravimetric-Differential Scanning Calorimetry (TG-DSC). The results show that the inclusion of ATFWs diminishes electrical conductivity (EC) and density while augmenting the flexural and compressive strengths of the composites. When extending the treatment duration of SFs in a 10% NaOH solution from 1 hour to 3 hours for SF-reinforced composites, the 360-day flexural and compressive strengths for samples without SFs show an enhancement of 1.1 times and 0.9 times, those with 1% SFs exhibit an increase of 0.7 times and 0.5 times, and those with 2% SFs demonstrate an improvement of 0.3 times and 0.4 times, respectively. Furthermore, the incorporation of ATFWs enables the physical embedding and sequestration of organic components released from SFs in a matrix without local aggregation. Therefore, recycling ATFWs as an alkaline activator is deemed feasible to produce SF-reinforced SP-based composites. The research outcomes offer an innovative approach for whole-waste utilization in the realm of natural fiber-reinforced composites.

Fertility and heavy metal pollution in silage maize soil irrigated with different levels of recycled wastewater under conventional and no-tillage practices

AbstractIrrigation with recycled domestic wastewater has been known to obtain positive effects on improving soil fertility, but it may also become a risk factor in case of causing an increase in soil salinity and/or heavy metal concentration of soil. No-tillage can retain soil moisture, helping to reduce irrigation water necessity, and thus lower amounts of heavy metals and salts are added to soil under wastewater irrigation conditions. The objective of this study was to analyze the effects of wastewater irrigation at different levels of on silage maize cultivation under conventional tillage and no-tillage conditions by comparing to full irrigation with fresh water. The two-year experiment was planned according to the split-plots design in the random blocks with three replications. The results indicated that full irrigation with wastewater increased soil salinity, organic matter content, total nitrogen, plant available phosphous, exchangeable cations, exchangeable sodium percentage and soil essential and non-essential heavy metal contents, but decreased soil pH and lime content. Increasing rates in organic matter content, total nitrogen, plant available phosphorus and exchangeable potassium were higher, but in electrical conductivity, and heavy metal accumulation were lower in soil under no-tillage as compared to conventional tillage. Contamination and enrichment factors and geographic accumulation index showed that non-essential heavy metal contamination due to cadmium and nickel, increased in full irrigation with wastewater. Irrigation with wastewater also increased heavy metal accumulation in silage maize. No-tillage can be a recommendable water management practice considering that the risks of soil salinity and heavy metal accumulation can be reduced and that soil fertility can be increased. Also, in reducing the risk of accumulation of cadmium and nickel in soil, 33% deficit irrigation with wastewater can make no-tillage more available.

ANALISIS PERTUMBUHAN EKONOMI DAN DAYA SAING DAERAH KABUPATEN ENDE TAHUN 2013-2014

This study is to empirically determine the potential economic sector, to see whether there has been a change in the economic structure and to determine which economic sectors have regional competitiveness in Ende Regency in 2013-2017 through data sourced from the Central Statistics Agency (BPS) of Ende Regency. The analysis technique used is the Location Quotient (LQ) analysis and Shift Share analysis, the results of the Location Quotient analysis show that the base sector for the 2013-2017 period is 1). Wholesale and retail trade, car and motorcycle repair (1.42); 2). Transportation and Warehousing Sector (1.28); 3). Real Estate Sector (1.17); 4) Manufacturing Industry Sector (1.14); 5). Education Service Sector (1.13); 6). Other Service Sector (1.12); 7). Waste Water Treatment and Recycling Sector (1,10); 8). Construction Sector (1.02). And the non-base sector is 1). Corporate Service Sector (0.03); 2). Food and beverage accommodation provision sector (0.49); 3). Information and communication sector (0.60); 4). Health Services and Social Activities Sector (0.82); 5). Government Administration, Defense and Compulsory Social Security Sector (0.84); 6). Agriculture, forestry and fisheries sector (0.92); 7). Electricity and Gas Procurement Sector (0.93); 8). Financial Services and Insurance Sector (0.98); and 9). Mining and Quarrying Sector (0.99). Based on the analysis of Shift Share, the sectors that have competitiveness in Ende Regency are 1). Growth of Agriculture, Forestry and Fisheries Sectors; 2). Mining and Excavation Sector; 3). Real Estate Sector; 4). Corporate Service Sector and 5). Education Service Sector.

Greenhouse gas production from an intermittently dosed cold-climate wastewater treatment wetland

This study explores the greenhouse gas (GHG) fluxes of nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) from a two-stage, cold-climate vertical-flow treatment wetland (TW) treating ski area wastewater at 3 °C average water temperature. The system is designed like a modified Ludzack-Ettinger process with the first stage a partially saturated, denitrifying TW followed by an unsaturated nitrifying TW and recycle of nitrified effluent. An intermittent wastewater dosing scheme was established for both stages, with alternating carbon-rich wastewater and nitrate-rich recycle to the first stage. The system has demonstrated effective chemical oxygen demand (COD) and total inorganic nitrogen (TIN) removal in high-strength wastewater over seven years of winter operation. Following two closed-loop, intensive GHG winter sampling campaigns at the TW, the magnitude of N2O flux was 2.2 times higher for denitrification than nitrification. CH4 and N2O emissions were strongly correlated with hydraulic loading, whereas CO2 was correlated with surface temperature. GHG fluxes from each stage were related to both microbial activity and off-gassing of dissolved species during wastewater dosing, thus the time of sampling relative to dosing strongly influenced observed fluxes. These results suggest that estimates of GHG fluxes from TWs may be biased if mass transfer and mechanisms of wastewater application are not considered. Emission factors for N2O and CH4 were 0.27 % as kg-N2O-N/kg-TINremoved and 0.04 % kg-CH4-C/kg-CODremoved, respectively. The system had observed seasonal emissions of 600.5 kg CO2 equivalent of GHGs estimated over 130-days of operation. These results indicate a need for wastewater treatment processes to mitigate GHGs.

Detection, Generation, and Control of Disinfection By-products of Reclaimed Water

At the time when water resources are in short supply,wastewater recycling is both an important environmental protection strategy and also a resource strategy. Disinfection is essential to ensure the biological safety of reclaimed wastewater by killing pathogens and preventing the spread of waterborne diseases. However,the disinfection process could inevitably produce toxic disinfection byproducts(DBPs)due to the reaction between the disinfectants and wastewater organic matters. Regarding wastewater DBPs,this study reviewed their identification methods,formation conditions(including precursors,the effect of water quality,disinfectants,and operational parameters on DBPs),and control methods(including source control,process control,and end control). In addition,future research trends of wastewater DBPs were discussed.

Development of novel high anti-pollution polyamide/polysulfate disk tubular reverse osmosis membrane modules and their application in simulated space bathing wastewater

Water is a precious resource in space stations, and wastewater recycling is necessary to meet the needs of astronauts. In that respect, applying the high anti-pollution disk tubular reverse osmosis (DTRO) technique is a reliable way to remove pollutes from wastewater. Thin film composite (TFC) membrane treatment is the most frequently employed solution for purifying wastewater in industry; however, the intrinsic weaknesses of polymer membrane substrates, e.g., poor mechanical property, foulant adsorption and low resistance to acidic/basic conditions, greatly hamper their applications. In this study, the novel polysulfate (PSE) membrane substrates were prepared via non-solvent induced phase separation (NIPS) method. The microstructure and performance of PSE membrane substrates were comprehensively investigated at varying polymer concentration and nanoparticle types. The results showed that adding nanosilver to the support layer significantly enhanced the TFC- PSE/Ag membrane performance (up to 57 %) and tensile strength (by 4.57 ± 0.13). According to computational fluid dynamics (CFD) simulations, the optimized geometric design of deflectors would have noticeably improved the flow field distribution and strength, which was consistent with experimental data. The DTRO modules enabled the effective management of wastewater using simulated space bathing wastewater. The effluent met the water reuse criteria in terms of COD concentration, NH3-N concentration, conductivity and turbidity whose respective values were 15 mg/L, 0.21 mg/L, 60 μS/cm, and 0.9 NTU. The proposed DTRO modules own antifouling and acid/alkaline-resistance, indicating their remarkable application potential in the large-scale recovery of bathing wastewater from the earth or space station.

Phosphorus-supplemented seawater–wastewater cyclic system for microalgal cultivation: Production of high-lipid and high-protein algae

The reuse of wastewater after seawater cultivation is critically important. In this study, a phosphorus-supplemented seawater–wastewater cyclic system (PSSWCS) based on Chlorella pyrenoidosa SDEC-35 was developed. With the addition of phosphorus, the algal biomass and the ability to assimilate nitrogen and carbon were improved. At the nitrogen to phosphorus ratio of 20:1, the biomass productivity per mass of nitrogen reached 3.6 g g−1 (N) day−1 in the second cycle. After the third cycle the protein content reached 35.7% of dry mass, and the major metabolic substances in PSSWCS reached the highest content level of 89.5% (35.7% protein, 38.3% lipid, and 15.5% carbohydrate). After the fourth cycle the lipid content maintained at 40.1%. Furthermore, 100.0% recovery of wastewater in PSSWCS increased the nitrogen and carbon absorption to 15.0 and 396.8 g per tonne of seawater. This study achieved seawater–wastewater recycle and produced high-lipid and high-protein algae by phosphorus addition.

Advancing electrodialysis with dually cross-linked PVDF-based anion exchange membranes having semi-interpenetrating networks

Electrically-driven membrane technology plays a crucial role in water treatment and purification, finding applications in various fields like saline water and wastewater desalination, saline concentration and wastewater recycling. The content of this study is based on dually cross-linking and hot-pressing on a PVDF blend, to fabricate a kind of anion exchange membranes (AEMs) having semi-interpenetrating network and thus improve the defect of the traditional heterogeneous AEMs. The research explores the impact of vinyl imidazole (VIM) and dimethylaminoethyl methacrylate (DMAEMA) monomers, primarily or dually cross-linking, and optimizes the membrane properties through a hot-pressing process. Under these optimized conditions, the resulting membranes exhibit robust mechanical properties and outstanding desalination capabilities, achieving an area resistance of 2.56 Ω cm2 (comparable to standard homogeneous membranes), a desalination rate of 97.26% (outperforming the Neosepta AMX: 76.90%), and a salt limiting concentration of 3.1 M (surpassing the heterogeneous AEM and Neosepta AMX). Notably, this synthesis method is characterized by its cheap raw material and low energy consumption. This research offers valuable insights for the advancement and large-scale implementation of anion exchange membrane desalination.

Optimized improvement of double-stage solar AES saline wastewater treatment system based on performance simulation and exergy analysis

Being an innovative, clean and high-efficiency double-stage solar air evaporating separation (AES) saline wastewater treatment system, it enables the full recovery of clean water and salt from saline wastewater. Nevertheless, there are still possibilities for optimized improvement in various aspects. Therefore, in this work, a well-established and accurately system simulation model is constructed, comprehensive performance is intensively analyzed, and different optimization and improvement methods are designed. Results demonstrate that among three potential improvements, “Improvement of three-stage switching operation” brings little effect, while “Improvement of distribution relationship” can effectively improve system adaptability to weather, particularly under overcast weather conditions. Moreover, “Improvement of regenerator” improves overall performance (gained output ratio (GOR), evaporation efficiency (EE) and overall system efficiency (ηsys), which are 20.11 %, 11.01 %, and 8.55 % higher than original system, respectively). Furthermore, the exergy analysis concludes that simultaneous implementation of “Improved distribution relations” and “Improved regenerators” is preferable. This improvement enhances system weather resilience and wastewater recycling capabilities in one fell swoop. This improved system can achieve an average GOR, ηsys and system exergy efficiency (ηex) of 2.588, 63.92 % and 2.849 %, respectively, throughout total summer months. Consequently, the best system improvement method is combining “Improvement of distribution relationship” with “Improvement of regenerator”.

Groundwater conservation, and recycling and reuse of textile wastewater in a denim industry of Bangladesh

Bangladesh holds the 2nd position after China in the global apparel market in terms of denim export. In the textile industry clusters of Bangladesh, the groundwater level is depleting at an alarming rate due to overconsumption and mismanagement. The present study evaluates the groundwater conservation potential of a denim facility in Manikganj District through an effluent recycling and reuse approach. In this study, 100% treated wastewater and 10% treated wastewater mixed with softwater were utilized in the wet processing plant to dye and wash sample denim products and investigated for their fabric quality using seven parameters. The test results followed the requirements given by the North American and European fashion brands that source denim products from Bangladesh. The feasibility assessment of groundwater conservation through its high (100%) and low (10%) recycling rates indicated that the studied facility can potentially save around 619,230 m3 and 61,923 m3 of groundwater in a year, respectively.