Removal Of Contaminants In Wastewater Research Articles

Moving Bed Biofilm Reactor (MBBR) for Decentralized Grey Water Treatment: Technical, Ecological and Cost Efficiency Comparison for Domestic Applications

The reuse of greywater has several advantages, including reduced freshwater extraction from rivers, aquifers, and groundwater; reduced need for desalination; less environmental impact from septic tanks and water treatment plants; decreased energy consumption; and reduced chemical pollution. The main objectives of this review study are to assess the technical attributes, ecological impacts, and cost-efficiency of Moving Bed Biofilm Reactor (MBBR) water treatment technology compared to similar available technology for small to medium-sized, decentralized applications in residential and commercial settings such as home gardening, sanitation, and landfills. Previous studies indicate that hybrid technologies such as MBBR are the most promising methods for the total removal of contaminants in wastewater in a decentralized setting. However, the initial capital cost of this technology for small and medium-scale domestic applications worldwide is high and so is a limiting factor in the expansion of its utilization. Expansion of domestic use of such Decentralized Wastewater Treatment Systems (DWTS) could increase the economies of scale and therefore reduce the initial capital costs for this useful water treatment. For the MBBR system, Chemical Oxygen Demand (COD) removal efficiency was found to be 70%, Total Suspended Solids (TSS) removal was found to be 97%, and turbidity removal was 98%

Biomimetic nanofiltration membranes: Critical review of materials, structures, and applications to water purification

Emerging contaminants generated due to industrialization have shrunken fresh water bodies. Nanofiltration membranes are relatively efficient at separating contaminants of various sizes and functionalities. Moreover, ease of scale-up, negligible environmental footprint, and energy recovery ability make membrane filtration a future technology for complex water purification. Biomimetic or bioinspired membranes are researched to overcome the permeability-selectivity tradeoff of the existing membranes. Since biological cell membranes can selectively transport various components across membranes via aligned channels, mimicking the architecture can enable the tunable selectivity and removal of various contaminants in wastewater. This comprehensive review examines recent advances in newer materials for biomimetic membranes, their characteristics, and their application for various wastewater treatments. We also discuss various challenges such as difficulty in mimicking the exact cell structure, fouling, and stability of biomimetic materials and present opportunities for further research. We conclude that reproducible and easy processing of biomimetic materials into membranes is required for commercial applications. This review aims at a brief and systematic overview of biomimetic membranes for wastewater treatment and a description of newer materials developed to mimic the biological membranes.

Production of highly effective adsorbent from tea waste, and its adsorption behaviors and characteristics for the removal of Rhodamine B

ABSTRACT The use of biowaste as an adsorbent for the removal of contaminants in wastewater with the adsorption process is very environmentally friendly, highly efficient, and economic. For this purpose, the hydrochar of tea waste (HTW) was obtained by hydrothermal treatment of the tea waste (TW), and then the active carbon of tea waste (ACTW) was obtained with the activation of KOH. The SEM, FTIR, BET, and pHzpc analyses were used in the characterisation of the adsorbent. The adsorption experiments were performed on the removal of Rhodamine B (RhB). For the adsorption isotherm studies, the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models were used, and it was determined that the most suitable model was the Freundlich isotherm with R2 = 0.992 and maximum adsorption capacity was 1666.7 mg/g. For the adsorption kinetic studies, the pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion models were used, and it was determined that the most suitable model was the pseudo-second-order with R2 = 0.999. With the analysis of thermodynamic parameters, it was obtained that the adsorption process was spontaneous (ΔG°≤ −9,025 kJ/mol) and endothermic (ΔH° = 22.447 kJ/mol). Lastly, it was found that the activation energy of the adsorption process was 16.95 kJ/mol, which indicates that it is physical sorption, and the rate constant of adsorption was 0.052 g/mg s. As a result, it was understood that the biomass-based ACTW can be used as an effective adsorbent and is a suitable adsorbent for the removal of RhB.

Electrolysis catalyzed ozonation for advanced wastewater treatment

The prohibitive cost of advanced oxidation processes (AOPs) necessitates the development of innovative variations to increase their applicability. This investigation evaluated the combination of ozonation and electrolysis using iron electrodes as a catalytic ozonation AOP for the mineralization of organic compounds in water. The operating parameters of initial pH and current density were optimized using response surface methodology (RSM) to maximize total organic carbon (TOC) removal from a dextrose based synthetic wastewater. The process was most effective for TOC removal in alkaline conditions (initial pH of 9), although performance compared to ozonation alone was more significantly enhanced in acidic conditions (initial pH of 3). TOC removal was found to increase as current density increased from 4 to 12 mA/cm2, regardless of initial pH, primarily due to the increased rate of catalyst addition from the sacrificial anode. It was determined that the initial pH of the system presented a more statistically significant effect on TOC removal than current density, although both parameters were determined to be relevant. Under optimal conditions of 12 mA/cm2 and an initial pH of 9, 63% TOC removal was achieved after 60 min of treatment. Catalyst dosage using electrochemical and chemical approaches was compared, finding that electrochemical catalyst dosage was preferred for TOC removal, illustrated by the pseudo-first order rate constant of observed TOC removal, which was 51–76% higher using the electrochemical approach. Using an indirect measurement method involving tert-Butyl alcohol, hydroxyl radicals were detected during the combined ozonation and electrolysis treatment. Radical production was found to be linked to the conditions which favoured TOC removal. The results of this study have demonstrated the ability of an electrochemical catalytic ozonation process to enhance the removal of organic contaminants in wastewater compared to ozonation alone, established the advantages of harnessing an electrochemically generated catalyst, and characterized the effect of key operating parameters on TOC removal performance and hydroxyl radical production.

Potential to remove heavy metals and cyanide from gold mining wastewater using biochar

Gold processing results in the generation of tailings wastewater which contain cyanide (CN−) and heavy metals ions such as chromium (Cr3+), iron (Fe2+), zinc (Zn2+), nickel (Ni3+), lead (Pb2+), manganese (Mn2+) and copper (Cu2+). On the other hand, low cost-based bio adsorbents have received a lot of interest as a source of bio-based wastewater treatment for removal of wastewater contaminants. This study looks at the potential to remove contaminants from gold processing tailing dams using saw dust-based bio char. The bio char was produced through slow pyrolysis at 500 °C for 2 h. The bio char was then ground to particle sizes in the range of 0.5–2.0 mm before use as the bio adsorption media. The tailings wastewater was then passed through wastewater at various bio char loadings ranging from 10 to 50 mg/L at a pH of 7.0 for a period of 2–14 h. The wastewater was characterised using the APHA standard methods before and after bio adsorption. The CN, Cr, Fe, Zn, Ni, Pb, Mn and Cu ions concentration significantly reduced after the bio adsorption process with efficiency decreases as high as 75%, 78%, 74%, 87%, 82%, 70%, 85% and 90% respectively. Bio adsorbents can be successfully used to remove contaminants in gold tailings dam wastewater.

Copper complex stabilized on magnetic lignosulfonate: a magnetically recyclable catalyst for removal of wastewater contaminants

Copper complex stabilized on magnetic lignosulfonate: a magnetically recyclable catalyst for removal of wastewater contaminants

Utilization of Spions for the Removal of Wastewater Contaminants- Dyes, Antibiotics and Heavy Metals

Utilization of Spions for the Removal of Wastewater Contaminants- Dyes, Antibiotics and Heavy Metals

Prototyping a spinning adsorber submerged filter for continuous removal of wastewater contaminants

Adsorption process is widely used for the removal of wastewater contaminants. Classic adsorption units are fixed beds and membrane filtration systems. In this work a novel configuration of a bench scale spinning adsorber submerged filter is proposed. Different prototypes of cylindric, truncated cone or prismatic spinning adsorbers were studied using activated carbon of different particle sizes GAC (1.5 mm, Granulated), μGAC (0.475 mm, microGranulated), and cPAC (0.237 mm, coarse Powder) as adsorbent, and azorubine as model adsorbate. High maximum azorubine adsorptions per unit mass of adsorbent of 214, 225 and 275 mg/g for GAC, μGAC and cPAC, respectively, were obtained using the Langmuir isotherm adsorption model. Batch adsorption followed pseudo-second order kinetics, and adsorbate uptake rate increased with decreasing adsorbent particle size. Best adsorption unit was a tank equipped with a spinning rectangular prism adsorber prototype all made of stainless-steel woven wire filter of 180 mesh size. Running at 600 rpm and filled with a high cPAC concentration (25 g/L), adsorber can remove azorubine at similar rates that the use of free moving cPAC. Adsorber unit can run in continuous mode and works even better as a novel spinning submerged filter where filtered flow exits from a central pipe axis. This integrated adsorption-submerged filtration operation mode offer the possibility of adding a high initial dose or a continuous dosing of adsorbent in the tank, increasing the adsorbent concentration of the unit. This system can also offer novel opportunities for wastewater contaminants removal using different adsorbent materials located separately.

Decolorization of industrial wastewater using electrochemical peroxidation process

In this study, decolorization of wastewater samples taken from the paper industry is investigated using electrochemical peroxidation process. The electrochemical peroxidation process is a part of electrochemical advanced oxidation processes, which is based on the Fenton’s chemical reaction, provided by addition of external H2O2 into reaction cell. In this study, iron is used as anode and graphite as cathode put at the fixed distance of 30 mm in a glass reaction cell. The cell was filled with the solution containing wastewater and sodium chloride as the supporting electrolyte. Factors of the process such as pH, current intensity, hydrogen peroxide concentration, and time of treatment were studied. The results illustrate that all these parameters affect efficiencies of dye removal and chemical oxygen demand (COD) reducing. The maximal removal of wastewater contaminants was achieved under acid (pH 3) condition, with the applied current of 1 A, and hydrogen peroxide concentration of 0.033 M. At these conditions, decolorization process efficiency reached 100 and 83 % of COD removal after 40 minutes of wastewater sample treatment. In addition, the electrical energy consumption for wastewater treatment by electrochemical peroxidation is calculated, showing increase as the current intensity of treatment process was increased. The obtained results suggest that electrochemical peroxidation process can be used for removing dye compounds and chemical oxygen demand (COD) from industrial wastewaters with high removal efficiency.

Lead-Tolerant Bacillus Strains Promote Growth and Antioxidant Activities of Spinach (Spinacia oleracea) Treated with Sewage Water

Irrigation with sewage-contaminated water poses a serious threat to food security, particularly in developing countries. Heavy metal tolerant bacteria are sustainable alternatives for the removal of wastewater contaminants. In the present study, four lead (Pb)-tolerant strains viz. Bacillus megaterium (N8), Bacillus safensis (N11), Bacillus sp. (N18), and Bacillus megaterium (N29) were inoculated in spinach and grown in sewage water treated earthen pots separately and in combination with canal water. Results showed that Pb-tolerant strains significantly improved plant growth and antioxidant activities in spinach and reduces metal concentration in roots and leaves of spinach plants irrigated with treated wastewater. Strain Bacillus sp. (N18) followed by B. safensis (N11) caused the maximum increase in shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, and leaf area compared to the uninoculated control of sewage water treated plants. These strains also improved antioxidant enzymatic activity including catalase, guaiacol peroxidase dismutase, superoxide dismutase, and peroxidases activities compared to the uninoculated control under sewage water conditions. Strain Bacillus sp. (N18) followed by B. safensis (N11) showed the highest reduction in nickel, cadmium, chromium, and Pb contents in roots and leaves of spinach compared to the uninoculated control plants treated with the sewage water. Such potential Pb-tolerant Bacillus strains could be recommended for the growth promotion of spinach after extensive evaluation under field conditions contaminated with wastewater.

A review of nanotechnological applications to detect and control surface water pollution

Surface water is extremely susceptible to pollution stemming from human activities, such as the expansion of urban and suburban areas, industries, cities, and agriculture. In fact, sources of surface water have become the most common discharge sites for wastewater, which may contain microorganisms, pharmaceutical waste, heavy metals, and harmful pollutants. As a reference standard for clean water, the water quality standards and index of Malaysia were used. In comparison with conventional wastewater treatment methods, new nanomaterial-based methods for water filtration and purification are drawing attention as more efficient methods for water pollution detection and treatment. This prompts the use of nanotechnology applications to control surface water pollution and quality, as surface water is the main source of water consumption for humans, animals, and plants. This paper reviewed the application of nanotechnology for the detection and treatment of surface water pollution to ensure the sustainability of a green environment. This paper also highlighted the application of nanotechnology, namely, nanofiltration membranes, photocatalysis, plasma discharge, and nano-adsorbents, in wastewater treatment, as well as the application of nano-sensors for monitoring surface water quality. The integration of nano-adsorbents in the conventional technology may increase treatment efficiency because nano-adsorbents have demonstrated remarkable performance in the removal of contaminants in wastewater. The hurdles, challenges, and outlook of nanotechnology for wastewater treatment were addressed in this review. The insights presented in this paper may provide opportunities and directions to expand studies pertaining to the applications of nanotechnology for future surface water treatment.

Removal kinetics and treatment efficiency of heavy metals and other wastewater contaminants in a constructed wetland microcosm: Does mixed macrophytic combinations perform better?

Eight constructed wetland microcosms have been designed using various combinations of three different macrophytes in single as well as mixed planting units. The removal efficiency of major water quality parameters such as biological oxygen demand, total phosphorus, soluble reactive phosphorus, ammonium, nitrate and nitrite-nitrogen and heavy metals was evaluated at three retention times. The potential of selected macrophytes for heavy metals uptake was also studied in terms of bioconcentration factor, translocation factor, aerial tissue concentration factor and root concentration factor. Constructed wetland microcosm unit designed using Pistia stratiotes and Phragmites karka exhibited higher removal potential with maximum decay constants for most of the heavy metals and other wastewater contaminants. Maximum translocation and bioconcentration factors were also expressed by Pistia stratiotes and Phragmites karka for Zn (0.69 and 1.69 respectively). However, the maximum root concentration factor and aerial tissue concentration factors were observed in Pistia stratiotes for Cu (0.35) and Zn (0.10) respectively. The paper reports significantly higher removal of wastewater contaminants including heavy metals in mixed species planting as compared to single species. The removal efficiencies for all metals studied in different constructed wetland microcosm units ranged from 43.80 to 63.67%, 75.92–92.07% and 82.17–98.58% for 3, 7 and 14 days retention time respectively. Relative higher values of decay constants were observed for Cr, Cd and Mn. However, the correlation studies between removal efficiencies of heavy metals and several other parameters exhibited significant variation over time.

A novel approach for the removal of Pb2+ and Cd2+ from wastewater by sulfur-ferromagnetic nanoparticles (SFMNs)

In the recent decades, due to rapid increase in industrialization, urbanization, anthropogenic activity in the catchments, removal of heavy metals contaminants in wastewater has become global challenges. Numerous advance technologies have been introduced to deal with these problems but failed in reducing adequate pollution load in the contaminated water and/or wastewater. In this study, sulfur-ferromagnetic nanoparticles (SFMNs) were synthesized by modification of nano-Fe3O4, which can be rapidly separated from the environment by an external magnetic field after in situ repair. Its structure and physical properties were characterized by conventional techniques included Transmission electron microscope (TEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The ability of the SFMNs to remove Pb2+ and Cd2+ was studied at different temperatures and initial metal ions concentrations. The adsorption kinetics showed that the adsorption equilibrium time of Pb2+ and Cd2+ was 300 min consequently adsorption process of SFMNs fit well (R2 > 0.99) with pseudo-second-order model. The adsorption thermodynamics showed that the adsorption of Pb2+ and Cd2+ on SFMNs is spontaneous (negative value of ΔG0) endothermic process (positive value of ΔH0) and fit well (R2 > 0.98) with the Langmuir isothermal model. Density functional theory (DFT) calculations show that SFMNs can transfer electrons to Pb2+ and Cd2+, and the metal ions form stable chelates on the ligand surface. This study implies that newly synthesized sulfur-ferromagnetic nanoparticles could play an instrumental role in metal ions removal from water and wastewater.

Overview of electrocatalytic treatment of antibiotic pollutants in wastewater

ABSTRACT Abuse of antibiotics in animal husbandry and medicine has led to severe environmental problems especially the risk of bacterial resistance. Different from common organic pollutants, antibiotics in wastewater could not be easily removed by biological treatment because of their poor biodegradability. Electrocatalysis including electrocatalytic oxidation and reduction has gained great attention for the removal of antibiotic contaminants in wastewater due to its advantages of high efficiency, simple operation, and thorough degradation. This review summarizes the common features and synthesis methods as well as research progress of electrode materials used in the electrocatalytic process for the treatment of antibiotics in the last five years. The removal mechanism and transformation pathways of antibiotics in the electrocatalytic oxidation and reduction processes are presented, especially to avoid the second pollution. Cost aspects in the electrocatalytic process are also discussed by considering practical applications and comparison with adsorption and photocatalysis process. Finally, several developing directions of electrocatalysis in the antibiotic wastewater treatment are proposed as a guidance for further research.

Facile preparation of lignosulfonate induced silver nanoparticles for high efficient removal of organic contaminants in wastewater

In this study, sodium lignosulfonate (NaLS) was selected as a versatile regulator that possesses a three-function of reducer, dispersant and stabilizer for the preparation of silver nanoparticles (Ag NPs), to finally fabricate sodium lignosulfonate/ silver nanoparticles (NaLS@AgNPs) nanocatalysts. It was found that Ag NPs have the smallest particle size (15 ± 5 nm) and uniform distribution at the optimal NaLS concentration of 1.8 mM. Also, the NaLS@AgNPs nanocomposites exhibited excellent catalytic performance for the catalytic degradation of methylene blue (MB) (almost 100 % removal rate in only 150 s of reaction time, k = 20.4 × 10−3 s-1). A highest methyl orange (MO) removal rate in a H2O2 system as high as 90 % within 200 min with an apparent rate constant k = 4.04 × 10−3 min-1 can be achieved. This work provides a practical and facile one-step approach for preparing “ideal” noble metal nanocatalysts with the assistance of versatile and abundant sodium lignosulfonate derived from pulping process for purifying organic contaminant-containing wastewater with high catalytic degradation efficiency.

Cultivation process of microalgae using wastewater for biodiesel production and wastewater treatment: a review

Combining microalgae cultivation with nutrient removal is a promising technique as it enables renewable energy generation with the additional potential removal of wastewater contaminants in a single process. Performance and total yield of this process are still below the standard for industrialization. Thus, optimization is needed to reach the feasibility and actualize the concept. Cultivation conditions and reactor design play essential roles in the application and feasibility of this process. Both aspects have been developed through the years to enable the industrial application of this concept. Cultivation conditions are usually categorized into trophic conditions in which each situation has its specific function and target of removal. These conditions, however, are also applied in various reactor systems. Closed photobioreactor and open pond are two central systems for the reactor. Two of the most applied reactor models in wastewater are reviewed here to create a broad picture of the algae cultivation process by emphasizing biomass production and considering different aspects.

Joint influence of hydraulic load and hydraulic retention time on oilfields wastewater contaminant removal dynamics in free water surface flow constructed wetland

Constructed wetlands have been proposed to address the frequency and magnitude of oil and gas-related environmental contamination. The effect of co-variation of hydraulic load and hydraulic retention time on the dynamics of contaminant removal efficiency of heterogeneous plant species was assessed using ordinary least squares regression. The results showed that hydraulic load (HL), hydraulic retention time (HRT) and plant species jointly explain 87%, 79%, 83%, 85% and 66% of the total variance in removal efficiency of conductivity, TDS, BOD, COD, and total coliform bacteria, respectively. The models also explain 86%, 80% and 81% of the variations in removal efficiency of oil and grease, total phosphorus, and nitrate. More than 90% of the explained variance of total coliform removal efficiency is jointly attributable to hydraulic load and retention time. Hydraulic load of 1000 L and retention time of 72 h (1000 L 72 h) recorded optimum removal efficiency for TDS and conductivity. Optimum removal efficiency for BOD, COD and total coliform bacteria were achieved at HL and HRT of 1000 L 72 h, 1000 L 48 h and 1250 L 24 h, respectively. Alternanthera philoxeroides recorded the highest removal efficiency for oil and grease, conductivity and TDS, whereas Ruellia simplex recorded the highest removal efficiency for COD. Typha latifolia had the highest removal efficiency for total phosphorus and nitrate. Plant species suppressed the relationship between HL and HRT (1250 L 48 h, 1500 L 72 h, 1750 L 48 h and 2000 L 48 h) and removal efficiency for conductivity. Similarly, plant species suppressed the relationship between 1000 L 48 h and 1750 48 h and removal efficiency for TDS. These relationships underscore the complex dynamics between optimal contaminant removal efficiency and required hydraulic load, hydraulic retention time and plant species.

Ammonia removal through combined methane oxidation and nitrification-denitrification and the interactions among functional microorganisms

It would be highly beneficial to use the methane produced by anaerobic digestion, which is low cost and accessible, as the carbon source in the removal of nitrogenous contaminants in wastewater. However, there is a knowledge gap regarding coupling systems that entail methane oxidation, nitrification, and denitrification, which restricts their industrial application. In this study, we acclimated a mixed culture to deal with simultaneous nitrification-denitrification coupled to methane oxidation in a laboratory-scale hollow-fiber membrane biofilm reactor, which achieved a steady ammonia removal rate of 38.09 mg N/(L•d). Furthermore, a series of batch experiments were conducted to test methane oxidation coupled to nitrate denitrification (AME-D3), nitrite denitrification (AME-D2), and simultaneous nitrification and denitrification (ME-SND). The molar ratio between methane consumed and nitrate reduced (C/N) equals 10 and 5 mol CH4C mol−1 NO3N in AME-D3 and AME-D2, averagely and respectively. Without methane injection, the removal of nitrates and nitrites was very low, indicating that the coupling of nitrate/nitrite denitrification and methane oxidation was beneficial. The average ammonia removal rates in the 20% O2 and 25% O2 groups were 20.06 and 22.03 mg N/(L•d) in the ME-SND system, respectively. Without methane, the ammonia oxidation rate declined, and large amounts of nitrite accumulated. As traditional ammonia and nitrite oxidation approaches are autotrophic, we proposed the possibility of heterotrophic nitrification-aerobic denitrification (HN-AD). To study the coupling systems, the microbial communities and functional bacteria were analyzed. The results indicated that the system contained a guild of methanotrophs (mainly Methylobacter) and HN-AD bacteria (mainly Chrysobacterium and Comamonas).

Use of synthetic polymers of pumice for the removal of chromium in the tannery industry

Synthetic inorganic polymers are materials called geopolymers that have structural characteristics used for the removal of contaminants in wastewater. Thanks to its easy synthesis and low production costs, they have become one of the most studied materials in removal processes. In the tannery industry, huge amounts of water are used, which are mixed with chromium salts and whose final disposal is made directly on the water slopes, becoming a serious environmental problem for the world. In this work, geopolymer synthesized with pumice was used to determine the efficiency in the removal of chromium in the wastewater of a tannery in the city of Bucaramanga, Colombia. Initially, aqueous solutions were prepared to study the influence of the contact time, the pH of the initial solution and the dose of adsorbent, on the removal capacity of the metal. The maximum adsorption was presented at nine hours and at a pH value of 4, by comparing the adsorption percentages it was found that the geopolymer has better removal capacity than the precursor material, in turn a study of the sorption kinetics using the Langmuir and Freundlich isotherm model were made. Obtained geopolymer and raw material were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscope, before and after the adsorption process.

A simple and efficient method for removal of phenolic contaminants in wastewater using polyacrylamide entrapped mushroom tyrosinase

A simple and efficient method for removal of phenolic contaminants in wastewater using polyacrylamide entrapped mushroom tyrosinase