Washing Effluents Research Articles

Solar photocatalytic processes for treatment of soil washing wastewater

In the present work the use of a sequence of two solar photocatalytic processes was investigated for the removal of copper, iron, zinc and ethylenediaminedisuccinic acid (EDDS), used as chelating agent, from real soil washing effluents. Removal efficiencies of 93.5% (copper), 99.6% (iron), 99.4% (zinc), 97.2% (EDDS) and 80.7% (TOC) were achieved through outdoor solar photocatalytic treatments using parabolic trough collectors and carried out in Naples (Italy, N 40°50′, E 14°12′) in the period June–July 2015. These removal efficiencies were achieved for an incident UVA solar energy per unit volume (Qj,n) of 580kJ·L−1, calculated by taking into account the irradiated surface area of the photoreactor estimated in the present work (9.79×10−2m2) and the solar irradiance measurements collected during the experiments.The results suggest that the two-step solar process adopted can be proposed as a useful solution to the problem of heavy metals and chelating organic agents removals from soil washing.The ecotoxicological assessment, using different living organisms (Daphnia magna, Vibrio fischeri, Pseudokirchneriella subcapitata, Lepidium sativum and Caenorhabditis elegans), showed a noticeable decrease of the ecotoxicity of the soil washing effluents after the two-step photocatalytic process.

Photocatalytic processes assisted by artificial solar light for soil washing effluent treatment.

Contaminated soil has become a growing issue in recent years. The most common technique used to remove contaminants (such as metals) from the soil is the soil washing process. However, this process produces a final effluent containing chelating agents (i.e., ethylenediaminedisuccinic acid, also known as EDDS) and extracted metals (i.e., Cu, Fe, and Zn) at concentrations higher than discharge limits allowed by the Italian and Brazilian environmental law. Therefore, it is necessary to develop further treatments before its proper disposal or reuse. In the present study, soil washing tests were carried out through two sequential paths. Moreover, different artificial sunlight-driven photocatalytic treatments were used to remove Cu, Zn, Fe, and EDDS from soil washing effluents. Metal concentrations after the additional treatment were within the Brazilian and Italian regulatory limits for discharging in public sewers. The combined TiO2-photocatalytic processes applied were enough to decontaminate the effluents, allowing their reuse in soil washing treatment. Ecotoxicological assessment using different living organisms was carried out to assess the impact of the proposed two-step photocatalytic process on the effluent ecotoxicity. Graphical Abstract ᅟ.

Accelerated co-precipitation of lead, zinc and copper by carbon dioxide bubbling in alkaline municipal solid waste incinerator (MSWI) fly ash wash water

Co-precipitation of Pb, Zn and Cu with Fe and Al colloids and CaCO3 when CO2 is bubbled into the solution of MSWI fly ash water washing effluent, which has a high pH value, high Ca2+ content and high amphoteric heavy metal concentrations.

Impact of graphene oxide embedded polyethersulfone membranes for the effective treatment of distillery effluent

In the present study, treatment of spent wash from distilleries was studied using graphene oxide (GO) flakes incorporated in polyethersulfone (PES) mixed matrix membranes (MMMs). Two different additives such as polyacrylic acid (PAA) and lithium chloride (LiCl) were also used separately in the casting dope solution of PES/GO. GO TEM analysis revealed that particles are wrinkled sheets-like multilayer structure. Multilayer structures exhibit better intercalate with polymer matrix to produce hybrid nanocomposite membranes. The TGA analysis has shown that GO has good miscibility in PES membrane. Water flux has been improved progressively for the additive combined GO incorporated PES MMMs. Further, contact angle value of the neat PES membrane showed 70.8° which was significantly reduced up to 58.4° for PES/GO/PAA membrane. This ensures that membrane surface hydrophilicity was improved considerably due to the existence of both groups, GO and PAA. Moreover, the membrane performance was evaluated in terms of permeate flux, flux recovery ratio and color removal efficiency for synthetic melanoidin solution as well as distillery spent wash effluent. A maximum of 54% color removal was observed for distillery spent wash effluent.

Simultaneous removal of heavy metals from field-polluted soils and treatment of soil washing effluents through combined adsorption and artificial sunlight-driven photocatalytic processes

This paper proposes a process for reducing the content of copper and zinc in polluted soils and a combined photocatalytic-physical process for the treatment of the soil washing effluents. For this purpose, real soil samples were taken from the “Land of Fires”, a region in Southern Italy which is known for its high incidence of cancer mortality. Ethylenediamine-N,N′-disuccinic acid (EDDS) was used to extract the heavy metals from the contaminated soil. The soil washing effluents were treated through a sequence of photocatalytic and adsorption processes to lower the concentration values of metals (Cu, Zn, Fe and Mn) below the limits of national legislation for discharge in municipal sewers and to remove the EDDS from the soil washing solutions. Ecotoxicological tests, using different living organisms (Daphnia magna, Vibrio fischeri, Pseudokirchneriella subcapitata and Lepidium sativum), were performed on the soil washing effluents before and after the treatments to assess the effects of the proposed combined process on the ecotoxicity of the soil washing solutions.

Electro-fermentation of real-field acidogenic spent wash effluents for additional biohydrogen production with simultaneous treatment in a microbial electrolysis cell

Real-field acidogenic effluents rich in short chain carboxylic acids/volatile fatty acids (VFA) were obtained from biohydrogen (H2) producing reactor operated with spent wash as substrate. A single chambered microbial electrolysis cell (MEC) was designed to electro ferment the effluents towards additional H2 production with simultaneous treatment using acid pretreated biocatalyst. The effect of VFA concentration (4000mg/l and 8000mg/l) on biohydrogen production with simultaneous remediation was studied at 0.2V and 0.6V applied potential along with closed circuit (CC) and control operations. Maximum cumulative H2 production (CHP) and hydrogen production rate (HPR) of 39.35ml and 0.057mmol/h was observed at 0.6V. VFA utilization as substrate was high at 0.6V (68%) followed by 0.2V (45%), CC (39%) and control (19%). Dehydrogenase activity, pH profiles, low redox slopes (βa and βc) and polarization resistance (Rp) at 0.6V corroborated well with the H2 production at both the VFA concentrations operated. Additional H2 recovery utilizing VFA rich effluents demonstrates the sustainability of this integrated approach through electro fermentation in a single chamber MEC.

Spent wash decolourization using nano-Al2O3/kaolin photocatalyst: Taguchi and ANN approach

The intense colour of the spent wash effluent leads to crucial ecological issue when released untreated into the environment. The decolourization of distillery spent wash effluent is known to be a very challenging task. In this study, the degradation of organic pollutants in the form of colour was performed using nano photocatalyst prepared using aluminium oxide (Al2O3) nanoparticle and kaolin clay. As-synthesized nano-Al2O3/kaolin composites were used as photocatalyst for colour degradation of spent wash effluent. The process parameters such as dosage, pH, temperature and agitation were optimized to attain the maximum decolourization efficiency. The structural and the textural characteristics of the photocatalyst were analysed by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, High Resolution Scanning Electron Microscope (HRSEM) and Energy Dispersive X-ray (EDAX). Optimization of the process parameters using Taguchi Orthogonal Array (OA) design resulted in a maximum of 80% spent wash decolourization. Using Artificial Neural Network (ANN), a two layered feedforward backpropagation model resulted as the best performance and predictive model for spent wash decolourization. The experimental data were found to be in excellent agreement with the predicted results from the ANN model.

Decolorization of distillery spent wash effluent by electro oxidation (EC and EF) and Fenton processes: A comparative study

In this study, laboratory scale experiments were performed to degrade highly concentrated organic matter in the form of color in the distillery spent wash through batch oxidative methods such as electrocoagulation (EC), electrofenton (EF) and Fenton process. The effect of corresponding operating parameters, namely initial pH: 2–10; current intensity: 1–5A; electrolysis time: 0.5–4h; agitation speed: 100–500rpm; inter-electrode distance: 0.5–4cm and Fenton's reagent dosage: 5–40mg/L was employed for optimizing the process of spent wash color removal. The performance of all the three processes was compared and assessed in terms of percentage color removal. For EC, 79% color removal was achieved using iron electrodes arranged with 0.5cm of inter-electrode space and at optimum conditions of pH 7, 5A current intensity, 300rpm agitation speed and in 2h of electrolysis time. In EF, 44% spent wash decolorization was observed using carbon (graphite) electrodes with an optimum conditions of 0.5cm inter-electrode distance, pH 3, 4A current intensity, 20mg/L FeSO4 and agitation speed of 400rpm for 3h of electrolysis time. By Fenton process, 66% decolorization was attained by Fenton process at optimized conditions of pH 3, 40mg/L of Fenton's reagent and at 500rpm of agitation speed for 4h of treatment time.

Influence of bentonite in polymer membranes for effective treatment of car wash effluent to protect the ecosystem

In this study, modified polyethersulfone (PES) and cellulose acetate (CA) membranes were used in the treatment of car wash effluent using ultrafiltration. Hydrophilic sulfonated poly ether ether ketone (SPEEK) and bentonite as nanoclay were used as additives for the PES and CA membrane modification. Performances of modified membranes were compared with commercial PES membrane with 10kDa molecular weight cut off (MWCO). The influencing parameters like stirrer speed (250–750rpm) and transmembrane pressure (100–600kPa) (TMP) were varied and their effects were studied as a function of flux. In the treatment of car wash effluent, a higher permeate flux of 52.3L/m2h was obtained for modified CA membrane at TMP of 400kPa and stirrer speed of 750rpm. In comparison with modified PES membrane and commercial PES membrane, modified CA membranes showed better performance in terms of flux and flux recovery ratio. The highest COD removal (60%) was obtained for modified CA membrane and a lowest COD removal (47%) was observed for commercial PES membrane. The modified membranes were better at removing COD, turbidity and maintained more stable flux than commercial PES membrane, suggesting they will provide better economic performance in car wash effluent reclamation.

Remediation of Arsenic Contaminated Soils and Treatment of Washing Effluent Using Calcined Mn-Fe Layered Double Hydroxide

Arsenic contaminated soil is a serious worldwide problem nowadays, and soil washing technique is one of hottest topics in the area of remediating arsenic contaminated soils, while treatment of the washing effluent is still an urgent problem. In this study, in order to select the best washing extractants for arsenic contaminated soil of the Xiangxi Autonomous Prefecture, nine kinds of extractants (citric acid, oxalic acid, malic acid, tartaric acid, H3PO4, KH2PO4, KOH, NH4Ac and ultra-pure water) were studied. Innovatively, a new material (calcined Mn-Fe Layered double hydroxide) was firstly introduced and fully applied to the adsorption of arsenic washing effluents. Results showed citric acid, oxalic acid and KH2PO4 were the optimal extractants for arsenic contaminated soil, considering the extraction rate and environmental perspective. When the concentrations were 200, 300, 300 mmol/ L , solution soil ratios were 10, 10, 20 mL/g , extraction times were 12,12,12 h, the citric acid, oxalic acid and KH2PO4, respectively, achieved the maximum extraction rate of 39%, 65% and 29%. Calcined Mn-Fe LDH used in this work was characterized by SEM and FT-IR, indicating the unique structure and high phase purity of the synthetic samples. For the 28mg/L arsenic effluent washing by citric acid, calcined Mn-Fe LDH showed the most effective capacity as adsorbent under neutral or weak base condition as well as 2 h absorption time.

Selective removal of polycyclic aromatic hydrocarbons (PAHs) from soil washing effluents using biochars produced at different pyrolytic temperatures.

Wheat straw biochars produced at 400, 600 and 800°C (BC400, BC600 and BC800) were used to selectively adsorb PAHs from soil washing effluents. For soil washing effluents contained Phenanthrene (PHE), Fluoranthene (FLU), Pyrene (PYR) and Triton X-100 (TX100), biochars at 2 (for BC800) or 6 g L(-1) (for BC400 and BC600) can remove 71.8-98.6% of PAHs while recover more than 87% of TX100. PAH removals increase with increasing biochar dose. However, excess biochar is detrimental to the recovery of surfactant. For a specific biochar dose, PAH removal and TX100 loss increase with increasing pyrolytic temperature. For BC400 and BC600, PAH removal follows the order of PHE>FLU>PYR, while the order is reversed with PYR>FLU>PHE for BC800. Biochars have much higher sorption affinity for PAHs than for TX100. It is therefore suggested that biochar is a good alternative for selective adsorption of PAHs and recovery of TX100 in soil washing process.

Acidogenic spent wash valorization through polyhydroxyalkanoate (PHA) synthesis coupled with fermentative biohydrogen production

The production of polyhydroxyalkanoates (PHAs) by Bacillus tequilensis biocatalyst using spent wash effluents as substrate was evaluated to increase the versatility of the existing PHA production process and reduce production cost. In this study, spent wash was used as a substrate for biohydrogen (H2) production and the resulting acidogenic effluents were subsequently employed as substrate for PHA production. Maximum H2 production of 39.8L and maximum PHA accumulation of 40% dry cell weight was attained. Good substrate removal associated with decrement in acidification (53% to 15%) indicates that the VFA generated were effectively utilized for PHA production. The PHA composition showed presence of copolymer [P (3HB-co-3HV)] with varying contents of hydroxybutyrate and hydroxyvalerate. The results obtained suggest that the use of spent wash effluents as substrate can considerably reduce the production cost of PHA with simultaneous waste valorization. PHA synthesis with B. tequilensis and spent wash effluents is reported for the first time.

Study of PCP Photodegradation by TiO<sub>2</sub> Catalyst Based on Different Properties of Soil Washing Effluents

Remediation of hydrophobic organic contaminants (HOCs) in soils and groundwater has becoming an issue of extensive concern around the world. Surfactant enhanced remediation has been suggested as a promising technology for abating such contaminants, and the nonionic surfactants have often been employed based on their high solubilization capabilities and comparatively low critical micelle concentrations (CMCs). A major problem arises after soil washing because the collected surfactant-containing wastes must be properly disposed or treated. In this study, 13 different soil with different basic properties were artificially contaminated with pentachlorophenol (PCP) and washed with TX100, a widely used nonionic surfactant. The properites of the as-required 13 washing effluents were test, and photocatalystic degradation of PCP using commercial P25 TiO2 was carried out. The degradation curves were fitted to the pseudo-first-order kinetic law, and simple correlation coefficients were obtained between the first-order rate constants k and washing effluents properties. The results obtained indicated that the degradation rate of PCP mainly depended on the concentration of PCP and TX100 in the wasted effluents, while othe substances washed out from soil showed very limited impact on the photocatalysis procedure.

유해원소로 오염된 토양 세척 및 세척수의 처리

본 연구에서는 유해원소로 오염된 현장토양을 대상으로 물리적 및 화학적 토양세척공법을 적용하였을 경우, 유해원소의 처리효율과 더불어 토양세척공법에서 발생하는 폐수를 중화, 응집, 흡착 반응을 이용하여 처리할 경우를 고려하여 최적 토양세척공법의 선정방법을 평가하고자 하였다. 본 연구에서 사용한 토양에서 주된 유해원소인 비소제거에 수산화나트륨 수용액이 황산 수용액보다 효과적이었다. 반면, 폐수 처리의 경우 수산화나트륨 수용액으로 토양 세척 시 함께 추출되는 토양유기물로 인하여 폐수처리가 복잡하고 유해원소의 제거가 잘되지 않아 세척공정의 세척제로는 산을 이용하여 토양을 세척하는 것이 좋으며, 발생하는 세척액의 pH를 6.5 이상으로 중화시켜 대부분의 유해원소를 제거할 수 있었다. 흡착제로 GFO(Granular ferric oxide)를 이용하였을 경우 비소와 납의 제거율이 뛰어났으며, 중화공정과 결합하였을 경우 대부분의 유해원소를 제거할 수 있었다. 결과적으로, 토양세척 공법 적용 시 토양의 특성에 따라 유해원소의 제거율 및 세척액의 처리 및 재이용 방법이 차이가 있으므로, 세척효율 및 세척수 처리 공정을 고려한 체계적인 최적화를 진행하여야 할 것으로 판단된다. This study evaluated the optimal soil washing conditions for toxic metals considering the removal efficiency of toxic metals from contaminated soils as well as from soil washing effluents. In the contaminated soils, As was the major contaminant and extracted by sodium hydroxide solution better than by sulfuric acid. However, in the case of the treatment of soil washing effluents, sodium hydroxide was less effective extractant because soil organic matter extracted by sodium hydroxide prevented the solid-liquid phase separation and toxic metal removal. In the treatment of soil washing effluents with sulfuric acid, toxic metals in the effluents were mostly precipitated at the pH above 6.5. In addition, granular ferric oxide (GFO) as an adsorbent enhanced the removal of As and Pb indicating that toxic metals in the washing effluents can be removed almost completely by the use of combined adsorption-neutralization process. This study suggests that soil washing techniques for toxic metals should be optimized based on the physical and chemical properties of the contaminated soils, the nature of chemical extractant, and the removal efficiency and effectiveness of toxic metals from the soils as well as soil washing effluents.

Biotreatment of Melanoidin-Containing Distillery Spent Wash Effluent by Free and Immobilized Aspergillus oryzae MTCC 7691

A total of three fungal isolates from samples collected at spent wash disposal area were screened for their ability to degrade melanoidin. Distillery molasses spent wash was decolorized, and its chemical oxygen demand (COD) was reduced in immobilized fungal bioreactor (IFB) in the absence of carbon and nitrogen source using fungal mycelia of Aspergillus oryzae MTCC 7691. Fungal mycelia immobilized on baggase packed in a glass column under a batch-wise mode (1) effected removal of 75.71 ± 0.12 % color, 51.0 ± 0.13 % biological oxygen demand (BOD), 86.19 ± 2.56 % COD, and 49.0 ± 0.12 % phenolic pigments of distillery spent wash up to 25 days at 30 °C, while free fungal mycelia resulted in removal of 63.1 ± 0.16 % color, 27.74 ± 0.14 % BOD, 76.21 ± 1.62 % COD, and 37.32 ± 0.17 % phenolic pigments of distillery spent wash using shake flask, (2) manganese peroxidase (MnP) activity was highest (1.55 ± 0.01 U ml−1 min−1) in immobilized fungi, followed by lignin peroxidase (0.65 ± 0.01 U ml−1 min−1) and laccase activity (0.9 ± 0.01 CU ml−1 min−1), (3) accumulative MnP activity was highly correlated with (r = 0.9216) spent wash decolorization and (r = 0.7282) reduction of phenolic pigments, suggesting the presence of MnP activities in bioremediation of spent wash and (4) degradation of spent wash was confirmed by high-performance thin layer chromatography and gas chromatography–mass spectrometry analysis. Measurement of chlorophyll a content of Chlorella species cultivated on treated spent wash effluent obtained from immobilized fungal bioreactor was 5.16 ± 0.71 μg ml−1 compared with 1.306 ± 0.017 μg ml−1 obtained with untreated spent wash. Thus, this work may provide a reasonable alternative for cost-effective bioremediation of distillery spent wash using immobilized A. oryzae on baggase fibers.

Ozone Treatment of Defrost Water for In-Plant Reuse

Many fruit and vegetable processing operations are examining technologies to reduce effluent volume and encourage water recovery and reuse. Implementing technologies and programs to promote in-plant reuse and recycling of discharge water is cost-effective and may improve processing efficiency. The efficacy of ozonation of defrost water has been investigated to determine the appropriate treatment level for in-plant reuse at a fruit processing plant in Clovis, California. Treatments of 0.5 ppm and 1.0 ppm of aqueous ozone achieved water quality acceptable for in-plant reuse, while an ozone treatment of 1.0 ppm was needed to significantly (P < 0.05) reduced the microbial load of flume wash effluent.

Car wash industry in Malaysia: Treatment of car wash effluent using ultrafiltration and nanofiltration membranes

Three different types of commercial membranes, i.e. UF PVDF100 (MWCO 100kDa), UF PES30 (MWCO 30kDa) and NF270 were used to treat car wash effluent and were evaluated with respect to permeate flux, rejection of conductivity, total dissolved solid (TDS), chemical oxygen demand (COD) and turbidity. Results revealed that NF270 exhibited greater flux stability and higher flux recovery during treatment process compared to PVDF100 and PES30 membranes, indicating its higher resistance against fouling. With respect to turbidity removal, it is found that minimum rejection of 92% could be achieved irrespective of membrane properties and effluent characteristics. The performance of membrane in COD reduction was however dependent on its properties in which NF270 showed the highest retention rate (70.9–91.5%) followed by PES30 (54.9–83.9%) and PVDF100 (56.1–82.4%). Compared to NF270, both UF membranes were found ineffective in reducing conductivity and TDS of effluent. NF270 displayed at least 60% separation rate in conductivity and TDS removal compared to 13.6–35.4% reported in PVDF100 and PES30 membranes. The features demonstrated by NF270 in separating the pollutants from the car wash effluent coupled with stable water production make the membrane a good candidate to be employed and offer an environmentally sustainable option to car wash industry.

Studies on sorption of plutonium from carbonate medium on polyacrylhydroxamic acid resin

Polyacrylhydroxamic acid resin synthesized by functionalization of polyacrylamide with hydroxylamine has been investigated for the sorption of plutonium(IV) from carbonate medium, aiming at its application for the removal of plutonium from alkali wash effluent generated during purification of TBP in PUREX process. Batch experiments have been carried out to determine distribution coefficient of plutonium(IV) between this exchanger and various compositions of carbonate medium. Effect of the concentration of sodium carbonate, sodium bicarbonate and pH of the solution on the distribution coefficient have been studied to optimize the conditions for the uptake of Pu(IV) by this exchanger. Column experiments were carried out to determine the practical capacity of the exchanger for plutonium. Elution studies were also carried out to recover the loaded plutonium from the ion exchange column The exchanger displayed good exchange capacity for Pu(IV) from feed solution simulating the conditions of carbonate wash effluent generated in PUREX process. The exchanger also exhibited fast elution of Pu, suggesting the feasibility of using it for the recovery of Pu from carbonate based wash effluent.

Feasibility of dairy waste water (DWW) and distillery spent wash (DSW) effluents in increasing the yield potential of Pleurotusflabellatus (PF 1832) and Pleurotus sajor-caju (PS 1610) on bagasse

In the present investigation, feasibility of dairy waste water (DWW) and distillery spent wash (DSW) effluents in increasing the growth and yield of two species of oyster mushroom, Pleurotus flabellatus (PF 1832) and P. sajor-caju (PS 1610) on abundantly available agro-waste, bagasse, was evaluated. Three different levels of treatments were applied for each effluent. The effects of amendments on the result were observed in terms of yield, biological efficiency (BE) and substrate dry-matter loss. BE was found to be the highest (66.63 ± 1.0 %) for P. sajor-caju grown on bagasse amended with 10 % DWW and lowest for Pleurotus controls. While P. sajor-caju performed better on bagasse amended with DWW, P. flabellatus was more suited to grow on DSW amended bagasse. Degradation of complex molecules was in accordance with substrate dry-matter loss and the respective yields. The biochemical analysis of mushroom fruit bodies showed them to be a rich source of protein (maximum 36.40 %) and sugars (maximum 41.58 %). The study thus proved to be beneficial for effective management of the waste by employing higher order fungi as well as obtaining nutrient-rich delicacy for the mass.

Purification of IgG from Sera of Rabbit and Guinea Pig by Flow-Through Mode Ion-Exchange Chromatography using DEAE Sepharose Fast Flow Column

A one-step purification process using flow-through mode ion-exchange chromatography (Ft-IEC) was evaluated for the purification of Immunoglobulin G (IgG) from rabbit and guinea pig serum. A simple protein precipitation with saturated ammonium sulfate was used to pretreated plasma samples. Chromatographic separation was carried out on DEAE Sepharose Fast Flow (F.F.) column at a flow rate of 1 mL min−1. Ft-IEC using Tris–HCl buffer at pH 7.0 allowed the recovery of 22% of the loaded IgG with purity of 95% existed in flowthrough and washing effluents but not in elution effluents. To be compared, bind-elute mode IEC using Tris–HCl buffer at pH 8.5 based on the routine protocol showed that the recovery of 15% of the loaded IgG with purity of 80% existed in elution effluents. These results indicate that the Ft-IEC is an effective method for purifying IgG from sera of rabbit and guinea pig and may also be suitable for other animal sera by adjusting pH at equilibrium buffer for chromatography column.