Effective treatment of high-salinity landfill leachate using ultraviolet/ultrasonication/ peroxymonosulfate system

Phthalate esters pollution in the leachate, soil, and water around a landfill near the sea, Iran

This investigation aimed to scrutinize the level of phthalate esters (PEs) in the landfill leachate of a coastal city in the north of the Persian Gulf and the sensitive ecosystem (soil and water) around it. Soil (two depths) and water samples were prepared from 5 stations in wet and dry seasons. The studied landfill leachate contained 114-303 μg/L of phthalates. The highest concentration of phthalates was related to bis (2-ethylhexyl) phthalate (3257 ng/g) in the wet season at surface soil (0-5 cm) in the landfill site, while the lowest one (6 ng/g) belonged to dimethyl phthalate at sub-surface soil at 700 m from the landfill in the dry season. A significant change in the level of Σ6PEs in the dry (303 μg/L) and wet (114 μg/L) seasons (P ≤ 0.05) was observed for water samples. The PE concentrations in wet times were higher in all soil depths than in dry times. With increasing depth, the content of phthalates decreased in all studied environments. A direct relationship was observed between the phthalates concentration and the pH value of leachate/water and soil. The PEs concentration was linked to electrical conductivity (leachate: R2 = 0.65, P < 0.01 and surface soil: R2 = 0.77, P < 0.05) and the soil organic content. The ecological risk of di-n-butyl phthalate, benzyl butyl phthalate, bis (2-ethylhexyl) phthalate, and di-n-octyl phthalate in the wet season was greater than one. The results showed that significant levels of phthalate esters are released from landfills to the surrounding environment, which requires adequate measures to maintain the health of the ecosystem and nearby residents.

Combination of coagulation, Fe0/H2O2 and ultra-high lime aluminium processes for the treatment of residual pollutants in biologically-treated landfill leachate

Refractory substances (humus) and salts (chloride (Cl-) and sulphate (SO42-) ions) remain in the biotreated landfill leachate treatment, and it is necessary to carry out further treatments by a suitable method before discharge. In this study, the effect and operational mechanism of a combination of the coagulation Fe0/H2O2 and ultra-high lime aluminium (UHLA) processes for the treatment of refractory organic substances and salts in the leachate effluent of a semi-aerobic aged refuse biofilter (SAARB) were investigated. The results showed that polyferric sulphate is a relatively efficient coagulant comparing to FeCl3, Al2(SO)4, and polyaluminium chloride. The Fe0/H2O2 process further removed refractory organics from wastewater, achieving 49.8% of total organic carbon removed. Further treatment by the UHLA process was carried. The results demonstrated that the amount of precipitant, reaction duration, and temperature had a significant impact on the Cl- and SO42- removals. After three treatments, the cumulative SO42- and Cl- removal efficiencies were 98% and 80%, respectively. The SO42- and Cl- were removed in the form of precipitates such as UHLA, specific components of which included calcium alumina, Fremy's salt of calcium, aluminium chloride, and calcium hydroxide. Overall, the UV254, CN, Cl-, and SO42- removal efficiencies from the SAARB effluent were 94.08%, 98.73%, 79.96%, and 98.44%, respectively, for the combined coagulation Fe0/H2O2 and UHLA processes. Therefore, the combined processes could effectively remove residual pollutants in the biologically-treated landfill leachate, and the study provides a useful reference for the removal of refractory organic matter and salts in landfill leachate.HighlightsCoagulation-Fe0/H2O2-UHLA process is effective to SAARB effluent treatment.Refractory organics are substantially degraded by the coagulation-Fenton-like stage.Both Cl- and SO42- in SAARB effluent are greatly removed by UHLA process.

Effective remediation of leachate concentrate by peroxymonosulfate in a catalytic ceramic membrane filtration process: Performance and mechanism

Membrane concentrated landfill leachate has been characterized by complex component and degradation resistant. In this work, a new catalytic ceramic membrane (CuCM) was developed by in-situ integrating copper oxide in the membrane and used in combination with peroxymonosulfate (PMS) for leachate concentrate treatment. The performance and key factors of the CuCM/PMS system were systematically studied. Results showed that the CuCM/PMS system experienced promising efficiency in the pH range of 3 ∼ 11. The highest COD, TOC, UV254 and Color removal efficiency achieved by the CuCM-3/PMS system under the conditions of pH = 7.0 and CPMS = 10 mM, which reached up to 63.4%, 50.5%, 75.1% and 90.2%, respectively. The possible mechanism of leachate remediation was proposed and non-free radicals (Cu(Ⅲ), 1O2) played an important role in the CuCM/PMS system for leachate remediation. The fluorescence spectrum and GC-MS analysis showed that the refractory organics with a high molecular weight in the leachate concentrate were mostly oxidized into small molecules, which also alleviated the membrane fouling. In addition, the slight decrease in COD (7.4%) and TOC (9.7%) after 6 cycles revealed the good catalytic stability and reusability of CuCM-3/PMS. This work provides a feasible strategy for leachate concentrate remediation via a nonradical oxidation process.

Elucidating sulfate radical-induced oxidizing mechanisms of solid-phase pharmaceuticals: Comparison with liquid-phase reactions

As a class of organic micropollutants of global concern, pharmaceuticals have prevalent distributions in the aqueous environment (e.g., groundwater and surface water) and solid matrices (e.g., soil, sediments, and dried sludge). Their contamination levels have been further aggravated by the annually increased production of expired drugs as emerging harmful wastes worldwide. Sulfate radicals (SO4•-)-based oxidation has attracted increasing attention for abating pharmaceuticals in the environment, whereas the transformation mechanisms of solid-phase pharmaceuticals remain unknown thus far. This investigation presented for the first time that SO4•-, individually produced by mechanical force-activated and heat-activated persulfate treatments, could effectively oxidize three model pharmaceuticals (i.e., methotrexate, sitagliptin, and salbutamol) in both solid and liquid phases. The high-resolution mass spectrometric analysis suggested their distinct transformation products formed by different phases of SO4•- oxidation. Accordingly, the SO4•--mediated mechanistic differences between the solid-phase and liquid-phase pharmaceuticals were proposed. It is noteworthy that the products from both systems were predicted with the remaining persistence, bioaccumulation, and multi-endpoint toxicity. Therefore, some post-treatment strategies need to be considered during practical applications of SO4•--based technologies in remediating different phases of micropollutants. This work has environmental implications for understanding the comparative transformation mechanisms of pharmaceuticals by SO4•- oxidation in remediating the contaminated solid and aqueous matrices.

Flocculation synergistic with nano zero-valent iron augmented attapulgite @ chitosan as Fenton-like catalyst for the treatment of landfill leachate

In this study, nano-zero-valent iron (NZVI) was added to attapulgite/chitosan and used as a catalyst in the heterogeneous Fenton process to degrade stabilized landfill leachate. Landfill leachate has serious environmental impacts due to the complexity and diversity of its pollutants. A magnetic catalyst (NZVI@PATP/CS) was prepared by a liquid-phase reduction method. The NZVI@PATP/CS were characterized by XRD, FTIR and SEM. The pH of leachate and the dosage of catalyst and H2O2 were changed to determine the best-operating conditions for the effective removal of chemical oxygen demand (COD) and total phosphorus(TP). To understand the adsorption degradation mechanism, the quenching experiments of free radicals were carried out. The results showed that the degradation rates of COD and TP were 66% and 92%, respectively, under the optimum pH value of 8, the dosage of H2O2 of 5 mL, and the dosage of the catalyst of 0.25 g for 60 min.

Occurrence and ecological risks of microplastics and phthalate esters in organic solid wastes: In a landfill located nearby the Persian Gulf

Landfill sites are the main source of plastic waste. Thus, municipal solid waste (MSW) in landfills may act as a reservior of microplastics (MPs) and related pollutants such as phthalate esters (PAEs) into surrounding environment. However, there is limited information on MPs and PAEs in landfill sites. Levels of MPs and PAEs in organic solid waste disposed in a landfill of Bushehr port were investigated for the first time in this study. The mean MPs and PAEs levels in organic MSW samples were 12.3 items/g and 7.99 μg/g, respectively, and the mean PAEs concentration in MPs was 87.5 μg/g. The highest number of MPs was related to the size classes of >1000 μm and <25 μm. The highest dominant type, color, and shape of MPs in organic MSW were nylon, white/transparent, and fragments, respectively. Di (2-ethylhexyl) phthalate (DEHP) and diisobutyl phthalate (DiBP) were the dominant compounds of PAEs in organic MSW. Based on the finding of present study, MPs showed a high hazard index (HI). DEHP, dioctyl phthalate (DOP), and DiBP demonstrated high-level hazards for sensitive organisms in water. This work illustrated considerable MPs and PAEs levels from an uncontrolled landfill without adequate protection, possibly contributing to their release into the environment. The sites of landfill located near marine environments, such as Bushehr port landfill adjacent to the Persian Gulf, may indicate critical threats to marine organisms and the food chain. Continuous landfills control and monitoring, especially the ones near the coastal area, is highly recommended to prevent further environmental pollution.

Activation of periodate using ultrasonic waves and UV radiation for landfill leachate treatment

In the present work, saline leachate of the Bushehr coastal city (Iran) was purified using the ultraviolet/ultrasonication wave/periodate process. The initial TDS and TOC values of the leachate studied were 7390 mg/L and 975 mg/L, respectively. During the effect of various parameters on leachate purification, the experiments were optimized at pH 3, oxidizer concentration of 4 mM, and treatment time of 120 min. The initial BOD₅/COD ratio of 0.66 was reduced to 0.42 at the end of the purification time (120 min). After leachate treatment under optimal conditions, the amount of BOD₅, COD, and UV₂₅₄ were 451.5 mg/L, 1072 mg/L, and 12.69 cm^-1, respectively. Concentrations of heavy metals in crude leachate by ICP-OES were checked. Also, the concentration of organic compounds before and after purification was determined using GC-Mass. The leachate purification kinetics followed the first-order model using the designed method. Based on the COD factor, the system energy consumption for leachate treatment was calculated to be 11.4 kWh/m³. The results showed that the system explored (UV/US/IO₄^-) can effectively purify high salinity waste leachate.

Occurrence, seasonal distribution, and ecological risk assessment of microplastics and phthalate esters in leachates of a landfill site located near the marine environment: Bushehr port, Iran as a case

Plastic wastes are produced in a large amount everywhere, and are commonly disposed in landfills. So landfill leachate seems an obvious source of microplastics (MPs) and phthalate esters (PAEs) due to a huge usage as plastic additives and plasticizers. But this issue still lacks attention and the present study provides the first information on the levels of MPs and PAEs in the fresh landfill leachate of Bushehr port during different seasons. The mean levels of MPs and PAEs in the fresh leachate in all seasons were 79.16 items/L and 3.27 mg/L, respectively. Also, the mean levels of PAEs in MPs were 48.33 μg/g. A statistically significant difference was detected in the levels of MPs and PAEs among different seasons with the highest values in summer and fall. MPs with a size of >1000 μm had the highest abundance in all seasons. The most prominent shape, color, and type of MPs in the leachate were fibers black, and nylon, respectively. Dibutyl phthalate (DBP) and Di(2-ethylhexyl) phthalate (DEHP) were the most dominant PAEs present in the leachate samples. The results of this study revealed high hazard index (HI) and pollution load index (PLI) of MPs in all seasons. Dioctyl phthalate (DOP), DEHP, DBP, diisobutyl phthalate (DiBP), butyl benzyl phthalate (BBP), and diethyl phthalate (DEP) represented a high risk to the sensitive organisms. The results of this study showed that significant levels of MPs and PAEs may release into the surrounding environment from the landfill sites without sufficient protection. This issue is more critical when the landfill sites in particular are located near the marine environments like the Bushehr landfill that is located near the Persian Gulf, which can lead to serious environmental problems. Thus permanent control and monitor of landfills, especially in the coastal areas are highly needed to prevent further pollution.

Simultaneous removal of organics and ammonia using a novel composite magnetic anode in the electro-hybrid ozonation-coagulation (E-HOC) process toward leachate treatment

To achieve simultaneous organics and ammonia (NH₄⁺-N) removal toward leachate treatment, this study designed a composite anode (CA⁺), in which iron powders were attracted to RuO₂-IrO₂/Ti tube surface by an inserted magnet and utilized in electro-hybrid ozonation-coagulation (E-HOC). The E-HOC (CA⁺) resulted in higher chemical oxygen demand (COD) and NH₄⁺-N removal with most content of CO₂/H₂O and gaseous N in product compared with E-HOC (Fe⁺), electrolysis ozonation and single ozonation. Reactive chlorine species (RCS) and coagulants were co-produced by compositing RuO₂-IrO₂/Ti and Fe powders, resulting in multiple reactions including electrocoagulation, ozone oxidation, synergistic between ozone and coagulants (SOC), electrolytic chloride and synergistic oxidation between active chlorine and ozone (SCO) occurred. Hydroxyl radical (•OH) generated through SOC reaction was promoted due the RCS generation in E-HOC. The interaction between •OH and Cl^-/ClO^- also contributed to enhanced Cl•/ClO• production. Consequently, synergy of chlorine, coagulants and ozone enhanced reactive species generation which contributed to favorable organics and NH₄⁺-N removal. Enhanced •OH and RCS are also attributed to conversion of bio-refractory organics like polyphenol, polycyclic aromatics and S-containing to biodegradable ones, e.g., aliphatic compounds and CHO. This study provides an easily operating strategy for leachate treatment with high content organics and NH₄⁺-N.

Enhanced removal of tetracycline via advanced oxidation of sodium persulfate and biochar adsorption

Advanced oxidation of antibiotic tetracycline (TC) is becoming an accessible and efficient technology. The removal of TC from the complex wastewater needs to be lucubrated. In this study, a TC removal system involving degradation and adsorption was established. TC degradation was accomplished by enhanced advanced oxidation via the addition of sodium persulfate (SP) and biochar into simulated wastewater containing Mn²⁺ and TC wastewater. The adsorption of TC and its derivatives was removed by biochar. The results indicate that the optimized reaction parameters were 3.0 g/L of biochar prepared at 600 °C (B600) and 400 mg/L of SP under acidic condition, and the removal percentage of TC was 87.48%, including 74.23% of degradation and 13.28% of adsorption; the anions Cl^-, NO₃^-, and H₂PO₄^- had negligible effects on the removal of TC in this Mn²⁺/B600/SP system. The system also functioned well with an aqueous solution with a high chemical oxygen demand (COD) concentration. Electron paramagnetic resonance (EPR) analysis indicated that ·OH and SO₄^- free radicals were present in the Mn²⁺/B600/SP system. Based on the testing and analysis results, a removal mechanism and potential TC degradation pathway for this system were proposed. TC can be degraded by ·OH and SO₄^- via three degradation pathways. Mn²⁺ can be precipitated as MnO₂, and a part of the TC and its derivatives can be adsorbed on the biochar surface. The Mn²⁺/B600/SP system also performed satisfactorily for a complex aqueous solution with various cations and antibiotics.

Experimental Study on the Treatment of Landfill Leachate by Electro-Assisted ZVI/UV Synergistic Activated Persulfate System

To solve the problem of the poor treatment of high concentration landfill leachate, an electro-assisted ultraviolet (UV)/zero-valent iron (ZVI) synergic activated persulfate (PS) system was used to treat landfill leachate. The effects of PS and ZVI dosage, initial pH value, and current density on the removal efficiency of COD and NH3-N in landfill leachate were investigated. The treatment effects of single PS, single electrochemical, UV/PS, electro-assisted ZVI activated PS, and electro-assisted ZVI/UV co-activated PS were compared. At the same time, UV-visible and three-dimensional fluorescence spectroscopy were performed on the landfill leachate before and after treatment. The results show that under the optimal conditions of initial pH = 3, the dosage of PS/12COD = 1, ZVI = 1.5 g/L, current density 62.5 mA/cm2, and t = 6 h, most of the macromolecular organic substances such as humic acid and fulvic acid were removed. Removal efficiencies of COD, NH3-N, and Chroma reached 81.99%, 89.90%, and 99.75%, respectively. The BOD5/COD value increased from 0.23 to 0.46. In addition, the radical identification results showed that the degradation of COD was due to the combined action of sulfate radicals (SO4•−) and hydroxyl radicals (•OH) and that SO4•− was dominant. The combined means of synergistic activation of PS for landfill leachate treatment was significantly better than that of single means of PS activation, confirming that electrically assisted ZVI/UV synergistic activation of PS is a promising method for landfill leachate treatment.

Advanced oxidation process based on hydroxyl and sulfate radicals to degrade refractory organic pollutants in landfill leachate

As a special type of wastewater produced in the landfill, leachate is mainly composed of organic pollutants, inorganic salts, ammonia nitrogen and heavy metals, and featured by high pollutants concentration, complex composition and large fluctuations in water quality and volume. Biological, chemical and physical methods have been proposed to treat landfill leachate, but much attention has been paid to the advanced oxidation processes (AOPs), due to their high adaptability and organic degradation efficiency. This paper summarizes the recent findings on the AOPs based on hydroxyl radical (OH) (e.g., ozonation and catalyzed ozone oxidations, Fenton and Fenton-like oxidations) and sulfate radical (SO₄^-) (e.g., activated and catalyzed persulfate oxidations), especially the production routes of free radicals and mechanisms of action. When dealing with some special landfill leachates, it is difficult for a single advanced oxidation technology to achieve the expected results, but the synergistic combination with biological or physical methods can produce satisfactory outcomes. Therefore, this paper has summarized the application of these combined treatment technologies on landfill leachate.

Thermal activation significantly improves the organic pollutant removal rate of low-grade manganese ore in a peroxymonosulfate system

Low-cost, eco-friendly and effective catalysts are essential for activating peroxymonosulfate (PMS) to purify water. Hence, we investigated using thermal activation natural low-grade manganese ore (CNMO) as an effective catalyst to activate PMS for the removal of Acid Orange 7 (AO7), a harmful azo dye. CNMO exhibited a more effective activation ability than either the pure component substances alone or natural manganese ore (NMO), owing to its increased charge transfer, pore size and acidic sites. The activation mechanism of PMS was elucidated, and the degradation of AO7 was noted to have been caused by singlet oxygen (¹O₂), and increased electron transfer. Moreover, the outstanding degradation of AO7 in actual water indicated that the CNMO/PMS system was highly resistant to surrounding organic and inorganic compounds, and the CNMO exhibited extraordinarily high stability and recyclability. Thus, this study provides not only a new choice of PMS activator that offers low cost, and excellent and stable performance, but also a novel direction for the efficient utilization of low-grade manganese ore.

Thermally activated natural low-grade manganese ore was used as an efficient and stable catalyst for enhancing the activation of PMS through increased charge transfer, pore size and acidic sites.

Influence of humic substances on the landfill leachate biodegradability with a focus on temporal seasonality

The high resilience to biological treatments from the landfill leachate is generally associated with the presence of humic substances (HS). The brown color characteristic of this effluent is also related to these substances. Landfill leachate with low biodegradability can make biological treatments unfeasible, which can drive up the cost for the treatment of large leachate volumes. In this context, this research aimed to characterize the leachate in different seasonal periods, and verify the influence of HS species on the biodegradability of the effluent to assist in the selection of adequate treatment techniques. The HS quantification was performed using the modified Lowry method and speciation through fractionation according to the molar masses of the HS species. The tropical regions can be the precursor for the rapid stabilization of biodegradable organic matter. The warmer climate contributed to a reduced BOD/COD ratio (0.03) and the predominance of compounds of lower mass (e.g.: fulvic acids). The tests showed an HS concentration of 26.9% of the total COD in the raw leachate in the rainy season, which increased to 37.3% in the dry season. Approximately 70% of HS species refer to fulvic acids, a fraction identified as having the highest biologic treatment resilience.

Optimization of heterogeneous Fenton-like process with Cu-Fe@CTS as catalyst for degradation of organic matter in leachate concentrate and degradation mechanism research

The heterogeneous Fenton-like process with bimetallic chelated magnetic chitosan aerogel (Cu-Fe@CTS) as catalyst was applied to treat pre-coagulated leachate nanofiltration concentrate. The process conditions were optimized by Box-Behnken Design (BBD) and the maximum UV₂₅₄ removal reached 96.06% under the conditions of temperature 87.62 °C, oxidant dosage 0.2395 mol/L and catalyst dosage 1 g/L. The TOC concentration was reduced from 847.5 to 99.7 mg/L and COD concentration was reduced from 1625 to 464 mg/L. The three-dimensional (3D) fluorescence analysis showed that most of Fulvic acid-like (FA-like) was removed. The adsorption experiment showed that the catalyst reached the adsorption balanced after 60 min and the corresponding FA adsorption removal reached 14.1%. The addition of Tert-butanol (TBA) reduced the FA removal by 59.4%, indicating that the hydroxyl radicals (OH) was the main active species. Experiments of the OH capture at different pH showed that the Fenton-like system produced more OH at pH of 4, at which the maximum FA removal was 96.61%, while the FA removal still reached 94.26% at pH of 7. The OH capture at different temperature showed that the Fenton-like system produced more OH at 90 °C. KI and TBA shielding experiments showed that OH was produced on the catalyst surface rather than being produced by catalysis of free metal ions in the solution.

Application of ultrasound irradiation in landfill leachate treatment

Landfilling is known to be the most widely used method in municipal solid waste management in many countries. Landfill leachate containing different recalcitrant compounds are recognized to contaminate the soil and water and accordingly threat both the human health and environment. A variety of chemical and biological methods have recently been employed for landfill leachate treatment, one of which is the ultrasonic process. In this review, the efficiency of the ultrasound-assisted method for leachate treatment, factors influencing the treatment process are studied by defining a search protocol. The results showed that ultrasound can reduce pollutants by creating cavitation, microstreaming, and microturbulence. Increasing turbidity in initial of irradiation time and increasing the cost of treatment are the disadvantages of using ultrasonic in leachate treatment. Moreover, ultrasound-assisted method leads to improve the leachate quality, especially the COD/BOD. Therefore, ultrasound can be considered a good pretreatment for biological processes. Although, the application of this process in combination with other treatment processes such as biological processes and advanced oxidation increases the efficiency of leachate treatment, its efficiency depends on several factors such as exploitation features and leachate quality.

Electrochemical activation of peroxides for treatment of contaminated water with landfill leachate: Efficacy, toxicity and biodegradability evaluation

Contaminated water with landfill leachate (CWLL) with high salinity and high organic content (total organic carbon (TOC) = 649 mg/L and Chemical Oxygen Demand (COD) = 1175 mg/L) is a toxic and non-biodegradable effluent. The present research aimed to assess the treatment effectiveness of CWLL by electrocoagulation (EC)/oxidant process. The ferrous ions generated during the process were employed as coagulant and catalyst for the activation of different oxidants such as peroxymonosulfate (PMS), peroxydisulfate (PDS), hydrogen peroxide (HP), and percarbonate (PC) to decrease TOC in CWLL. Removal of ammonia, color, phosphorous, and chemical oxygen demand (COD) from CWLL effluent was explored at various processes. EC/HP had the best performance (∼73%) in mineralization of organic pollutants compared to others under the condition of pH 6.8, applied current of 200 mA, oxidant dosage of 6 mM, and time of 80 min. The oxidation priority was to follow this order: EC/HP > EC/PMS > EC/PDS > EC/PC. These processes enhanced the biodegradability of CWLL based on the average oxidation state and biochemical oxygen demand (BOD)/COD ratio. SUVA₂₅₄ and E₂/E₃ indices were also investigated on obtained effluents. The phytotoxicity evaluation was carried out based on the germination index, indicating that the electro-activated oxidant was an effective system to reduce the toxicity of polluted waters. EC/HP showed supremacy compared to others in terms of efficiency, cost, and detoxification. Therefore, the electro-activated oxidant system is a good means for removing organic pollutants from real wastewater.

Kinetics of the Organic Compounds and Ammonium Nitrogen Electrochemical Oxidation in Landfill Leachates at Boron-Doped Diamond Anodes

Electrochemical oxidation (EO) of organic compounds and ammonium in the complex matrix of landfill leachates (LLs) was investigated using three different boron-doped diamond electrodes produced on silicon substrate (BDD/Si)(levels of boron doping [B]/[C] = 500, 10,000, and 15,000 ppm—0.5 k; 10 k, and 15 k, respectively) during 8-h tests. The LLs were collected from an old landfill in the Pomerania region (Northern Poland) and were characterized by a high concentration of N-NH₄⁺ (2069 ± 103 mg·L⁻¹), chemical oxygen demand (COD) (3608 ± 123 mg·L⁻¹), high salinity (2690 ± 70 mg Cl⁻·L⁻¹, 1353 ± 70 mg SO₄²⁻·L⁻¹), and poor biodegradability. The experiments revealed that electrochemical oxidation of LLs using BDD 0.5 k and current density (j) = 100 mA·cm⁻² was the most effective amongst those tested (C_8h/C₀: COD = 0.09 ± 0.14 mg·L⁻¹, N-NH₄⁺ = 0.39 ± 0.05 mg·L⁻¹). COD removal fits the model of pseudo-first-order reactions and N-NH₄⁺ removal in most cases follows second-order kinetics. The double increase in biodegradability index—to 0.22 ± 0.05 (BDD 0.5 k, j = 50 mA·cm⁻²) shows the potential application of EO prior biological treatment. Despite EO still being an energy consuming process, optimum conditions (COD removal > 70%) might be achieved after 4 h of treatment with an energy consumption of 200 kW·m⁻³ (BDD 0.5 k, j = 100 mA·cm⁻²).

Ibuprofen elimination from water and wastewater using sonication/ultraviolet/hydrogen peroxide/zeolite-titanate photocatalyst system

The present investigation was designed to remove ibuprofen from aqueous solutions and wastewater by activating hydrogen peroxide using ultrasonication (US)/ultraviolet (UV) radiation/zeolite-titanium. The physical-chemical properties of the photocatalyst were determined using BET, FTIR, XRD, FESEM, and EDX-mapping techniques. The titanium oxide crystal size and the catalyst BET were determined to be 4.97 nm and 39.88 m²/g, respectively. Tests were performed in a reactor (with a volume of 316 mL) located in an ultrasonic bath to intensify reactions. The synergistic impact of the components of the UV/US/H₂O₂/Photocatalyst system was explored. The maximum efficiency (99.58%) was obtained at H₂O₂ concentration of 0.05 mM, pH 5, UV power of 6 W, photo-catalyst dose of 1 g/L, and contact time of 100 min. The pH variable was more effective than the other parameters. Ions of NO₃^-, Cl^-, and SO₄^2- had a slightly negative effect on contaminant removal efficiency. The ibuprofen removal (based on COD) from urban water and hospital wastewater was attained 77.82% and 66.24%, respectively. The ibuprofen removal by the developed system followed the first-order kinetic. The results show that the system has high efficiency and reasonable costs (with treatment cost of 6.25 €/m³) for ibuprofen decontamination.