Compounds In Industrial Effluents Research Articles

Photocatalytic Degradation of Methylene Blue Dye with Green Zinc Oxide Doped with Nitrogen

The non-biodegradability of organic pollutants and their adverse effects on plant and living organisms makes their removal from the environment vital for the preservation of the ecosystem. In this study, Photocatalysis (one of the advanced oxidation processes) was employed for the removal of methylene blue dye (MBD). Phyto-enhanced synthesized Zinc oxide (G.S ZnO) were precipitated from an aqueous solution of zinc nitrate hexahydrate and Papaya leaf extracts. The precipitates were dried at 100 oC for 24 hours, and doped hydrothermally with nitrogen from Urea at different doping ratios (10%, 5% and 2%). Preliminary degradation of MBD with the different compositions of Photocatalyst revealed that 5% G.S N-ZnO had superior photocatalytic capabilities than pure ZnO, 10% G.S N-ZnO, 2% G.S N-ZnO. The effects of solution pH, 5% G.S N-ZnO dosage and initial solution concentration on MBD degradation were studied. An optimum percentage degradation of 83% and 97.5% were observed for pure ZnO and G.S. N-ZnO photocatalyst at a solution pH of 9.0, MB solution concentration of 10 mg/L and photocatalyst of dosage of 100 mg. Scanning Electron Microscope (SEM), X-ray Diffraction (XRD), Brunauer-Emmett-Teller (BET) and Fourier Transform Infrared Spectroscopy (FTIR) were used to study morphology, structural properties, surface area and pore volume, and functional groups of Pure ZnO and 5% G.S N-ZnO. FTIR spectra of the 5% G.S N-ZnO was in the range of 4000-500cm-1, and the ZnO group of G.S N-ZnO was at a low wavenumber. The BET result revealed the surface area of 5% G.S N-ZnO to be 113.3cm2/g which was five times that of pure ZnO. The BET result showed an increase in pore volume and diameter (2.118nm and 0.055cm3/g) of 5% G.S N-ZnO against that of pure ZnO (1.452 nm and 0.010 cm3/g). The shift of the XRD pattern between pure ZnO and 5% G.S N-ZnO affirms the presence of dopants in the crystalline structure of ZnO. The average crystallite sizes of pure ZnO and 5% G.S N-ZnO were 34.7nm and 24.8nm, respectively. The findings from this research revealed that the simultaneous use of green synthesis and doping could further improve the degradation of methylene blue dye compounds in industrial effluents and ultimately increase the efficiency of wastewater treatment processes/systems.

Synthesis and characterization of activated carbon of Moringa oleifera Lam pod and evaluation of its performance in the removal of oils and greases

Produced water treatment is crucial since its improper disposal can result in ecological damage. A widespread and effective technology for removing organic compounds in industrial effluents is adsorption. Approaches to treating real produced water using activated carbon with different activating agents lack discussions in the literature. The present study aimed to investigate the influence of acids, salts, and bases on the structure development of three activated carbon and their performance to remove oil and greases content (OGC) in produced water from an oil field. Moringa oleifera Lam was used as precursor material, and the influence of activating agents such as zinc chloride (ZnCl2), phosphoric acid (H3PO4), and sodium hydroxide (NaOH) was investigated. The adsorbents were characterized by elemental analysis (CHN), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and textural properties. The kinetic study showed that the pseudo-second-order kinetic model better represented the adsorbents. Among the activating agents, H3PO4 proved to be the most appropriate for producing an adsorbent with a large BET surface area, 1356.29 m2/g, and reaching an adsorption capacity equal to 294.41 mg/g. In addition, its chemical balance was described by Langmuir isotherm, suggesting chemical adsorption, while Freundlich isotherm adjusted well to experimental data of activated carbon with zinc chloride. Results indicated activated carbon with phosphoric acid or zinc chloride as alternative adsorbents for removal OGC since both had a percentage of oil and grease removal greater than 93%.

Impact of Urea and Ammoniacal Nitrogen Wastewaters on Soil: Field Study in a Fertilizer Industry (Bahía Blanca, Argentina).

Nitrogen compounds in industrial effluents are considered a serious threat to the environment. The aim of this work is to identify the effect produced by nitrogen-rich wastewater on alkaline soils from industrial land. Two plots were irrigated with wastewater as ammoniacal nitrogen (31 to 53g N m-2) and urea (167-301g N m-2) sources named P1 and P2, respectively. Inorganic nitrogen (N) concentrations (N-NH3 + N-NH4, N-NO2, N-NO3), soil pH, and N-NH3 volatilization were monitored during a 2-year period. Variations in the fate of N compounds were distinguished according to the quantity and source of N applied to the soil. A higher N input in the form of urea was related to a greater concentration of nitrates and soil acidification in the topsoil (0-30cm). Otherwise, ammoniacal N wastewater showed greater relative ammonia losses due to volatilization. Ammonia losses were estimated as 24.2% and 7.43% of the total N applied in P1 and P2, respectively. Besides, in P1 ammoniacal N predominated over nitrate, unlike results obtained in P2. The correct management of nitrogen-rich wastewaters in fertilizer industries could greatly reduce soil and groundwater degradation.

Wastewater treatment and Mycoremediation by P. ostreatus mycelium

Wastewater from industries contains a considerable amount of chemicals and is characterized by high biological oxygen demand (BOD), heavy metals, intense color and are thus toxic to the environment. White-rot fungi such as Oyster mushrooms are comprised of high biomass and various degradative enzymes that add to another dimension of use, such as mycoremediation. The mushroom was maintained in vitro in mycelial form. Remazol Brilliant Blue R (RBBR), Methyl Red (M.R.), and Malachite Green (M.G.) dyes, which are recalcitrant dyes that are often used for the preparation of many polymeric dyes, and textile dyeing, were used to test the decolorization potential of natural isolates of oyster mushroom. Mycelium was grown in the presence of RBBR, MR, and M.G. at a concentration of 100μM. It was found to decolorize more than 70%, 95%, and 80% of RBBR, MR, and M.G. dye, respectively, within 6 days. Mushroom mycelium was also tested for its lead tolerance and heavy metal biosorption potential. Lead tolerance was studied up to 500mg/L, which shows species′ latent growth with fungal morphology changes. Biosorption ability was observed by the use of Inductively Coupled Plasma spectrometry, which shows lowered concentrations of heavy metals (Pb, Cr, Ni) after 5 days of mycelial growth in the presence of these metals. The isolated strain was also found to have significant decolorizing and degrading potential for synthetic dyes and phenolic compounds in industrial effluents. This study focuses on edible oyster mushrooms′ ability to develop environmentally less aggressive processes in the treatment of industrial effluents.

Organic ligands unexpectedly increase the toxicity of chromium(III) for luminescent bacteria

Organic ligands are commonly believed to decrease the toxicity of metal ions, but there is few experimental evidence, especially for chromium (Cr(III)), which often coexists with organic compounds in industrial effluents. Here, the complexation of Cr(III) with acetate, lactate, l-tartrate, biphthalate and oxalate was tested under the conditions of a toxicity test, with high ion strength, by spectroscopic techniques. The stability constants of the complexes were found to follow the order Cr(III) oxalate > Cr(III) lactate > Cr(III) biphthalate > Cr(III) L-tartrate > Cr(III) acetate. Then, aquatic toxicity of Cr(III) to Photobacterium phosphoreum for a 15-min exposure period was tested in the absence and presence of organic ligands. Results unexpectedly show that the complexation of Cr(III) with acetic, lactate, l-tartrate and biphthalate resulted in enhanced toxicity to luminescent bacteria, whereas the coordination of Cr(III) with oxalate sharply alleviated the toxicity of individual oxalate and inorganic Cr(III), which was further confirmed by the scanning electron microscopy (SEM). Our findings show thus that organics do not always mitigate the toxicity of Cr(III) in acidic water.

Efficient removal of p-nitrophenol from water using montmorillonite clay: insights into the adsorption mechanism, process optimization, and regeneration.

The present research highlights the use of a montmorillonite clay to remove p-nitrophenol (PNP) from aqueous solution. The montmorillonite clay was characterized using powder X-ray diffraction, Fourier-transformed infrared spectroscopy, scanning electron microscopy, X-ray fluorescence, Brunauer-Emmett-Teller analyses, and zero point charge in order to establish the adsorption behavior-properties relationship. The physiochemical parameters like pH, initial PNP concentration, and adsorbent dose as well as their binary interaction effects on the PNP adsorption yield were statistically optimized using response surface methodology. As a result, 99.5% removal of PNP was obtained under the optimal conditions of pH 2, adsorbent dose of 2 g/l, and PNP concentration of 20 mg/l. The interaction between adsorbent dose and initial concentration was the most influencing interaction on the PNP removal efficiency. The mass transfer of PNP at the solution/adsorbent interface was described using pseudo-first-order and intraparticle diffusion. Langmuir isotherm well fitted the experimental equilibrium data with a satisfactory maximum adsorption capacity of 122.09 mg/g. The PNP adsorption process was thermodynamically spontaneous and endothermic. The regeneration study showed that the montmorillonite clay exhibited an excellent recycling capability. Overall, the montmorillonite clay is very attractive as an efficient, low-cost, eco-friendly, and recyclable adsorbent for the remediation of hazardous phenolic compounds in industrial effluents.

Optimization of sono-Fenton degradation of Acid Blue 113 using iron vanadate nanoparticles

ABSTRACTIron vanadate (FeVO4) nanoparticles were synthesized by hydrothermal method and used as heterogeneous Fenton-like catalyst in ultrasound (US)-assisted degradation of Acid Blue 113. By using a quadratic response surface model, more than 99% color removal and 80% TOC reduction were obtained using low amounts of catalyst and H2O2 at short reaction time and circumneutral pH condition. The synthesized nanocatalyst also exhibited a good reusability under US irradiation. The results indicate that the proposed sono-Fenton-like process is efficient for the treatment of recalcitrant compounds in industrial effluents.

Decolouration of laboratory dyes by immobilized cells of <i>Pseudomonas aeruginosa</i> and <i>Bacillus subtilis</i> at different carbon sources

Dyes are indicated as one of the most problematic compounds in industrial effluents. This is due to their high solubility and low degradability. The aim of the study was to evaluate the effect of external carbon source on decolouration of bromothymol blue, crystal violet and methylene blue by alginate immobilized cells of Bacillus subtilis and Pseudomonas aeruginosa . A total of five carbon sources (fructose, sucrose, glucose, methanol, lactose and sodium acetate) were used for the study. The study revealed highest decolouration of the bromothymol blue occurring in media that contained sodium acetate as external carbon source. Decolouration rate of bromothymol blue was observed to increase from 25.49 % and 18.17 % (at 24 h incubation) to 51.49 % and 31.94 % (at 144 h incubation), in presence of the Bacillus subtilis and Pseudomonas aeruginosa immobilized cells. For decolouration of the crystal violet, glucose and sodium acetate were observed to be the most appropriate carbon sources. With glucose as carbon source in the media, decolouration rates of 57.48 % and 41.23 % at the end of incubation were observed for the crystal violet dyes in presence of the Bacillus subtilis and Pseudomonas aeruginosa cells, respectively. None of the carbon sources used for the investigation was found to enhance decolouration of the methylene blue by the test bacteria species. The study revealed the possible application of the immobilized cells in scale up studies for the remediation of textile effluents. Keywords: Decolouration,Dye,Immobilizedbacteria,Wastewater

Immobilization of Pseudomonas putida A (ATCC 12633) cells: A promising tool for effective degradation of quaternary ammonium compounds in industrial effluents

Pseudomonas putida A (ATCC 12633) were encapsulated in Ca-alginate and their ability to degrade the quaternary ammonium compounds (QACs) tetradecylbenzyldimethylammonium chloride (C14BDMA), hexadecylbenzyldimethylammonium chloride (C16BDMA) and benzalkonium chloride (BAC) (a mixture 1:1 of C14BDMA and C16BDMA), was tested and compared with the degradation of the same compounds by freely suspended cells. Degradation was carried out in pH 7.4 buffered medium, at 30 °C with agitation at 100 rpm. After 24 h of incubation immobilized cells degraded 90% of 35–315 mg l−1 of C14BDMA, C16BDMA and BAC, whereas free cells were unable to degrade concentrations above 35 mg l−1. Immobilized cells of P. putida removed 80% QACs of an industrial effluent in 48 h under both sterile and non-sterile conditions. Degradation of QACs carried out using the non-sterilized effluent showed that the beads could be reused up to four cycles without changing the degradation efficiency. The reduction in the QACs concentration after treatment with immobilized cells can be correlated with the reduction in the phytotoxicity to Lactuta sativa seed germination and root elongation. We conclude that immobilized QACs-degrading bacteria represent a promising tool for bioremediation of QACs in industrial wastewater systems.

Application Photocatalysis for Treatment of Industrial Waste Water—A Short Review

Occurrence of persistent organic compounds in industrial effluents and their efficient removal technique has emerged as a crucial problem to waste water treatment plants. This review aims to focus on the plight associated with the effluents from textile industry, agricultural and pharmaceutical effluents. The occurrence of dyes, pesticides and endocrine disrupting chemicals in aquatic ecosystems may cause chronic diseases, affect the human endocrine system and have appeared as crucial factor to consider for drinking and non-potable end uses of water. Extensive researches have been attempted to screen effective and safe method of contaminants removal by modifying conventional treatments as well as advanced processes by renowned authors. This paper aims to review different possible routes of effluent treatment emphasizing on complete mineralization of the targeted contaminants. With this purpose, a comprehensive review has been presented to deliver essential information about dealing with photocatalytic mineralization of pollutants.

Characterization of Ta-Doped Titanium Dioxide Nano Particles Produced by Sol-Gel Method

Titanium dioxide also known as titania is a ceramic material. It is probably the most investigated inorganic oxide in recent years because of its non toxic nature, chemical stability and its potential effectiveness for destruction of toxic organic compounds in industrial effluents. In the present study pure and Ta doped TiO2 nanosize particles were prepared by sol-gel method. Samples with doping concentrations varying from 0.50 to 1.50 at % Ta and calcinations temperatures from 300 to 900 oC were synthesized. Changes taken place in phase transformation of the samples doped with Ta and undoped TiO2 were investigated. The effect of dopant concentration, calcinations temperature and particles size on anatase to rutile phase transformation was studied in detail. The samples were analyzed by various standard analytical tools.

Removal of SiO2 nanoparticles from industry wastewaters and subsurface waters by ultrafiltration: Investigation of process efficiency, deposit properties and fouling mechanism

The novel properties of nanomaterials offer great promise of new technological breakthroughs. Consequently, their use in industry is expanding, and with it the risk of their being released in industrial effluents, and later in surface waters. This raises the problem of potential environmental hazards that are as yet unknown. The work presented in this paper evaluates the feasibility of membrane ultrafiltration for the removal of SiO2 nanoparticles (78nm mean hydrodynamic diameter) in suspension at 0.14wt% with the objective of treating them as pollutant compounds in industrial effluents. Regenerated cellulose membranes with two MWCOs of 10 and 100kDa were implemented. The influence of the membrane MWCO, the TMP and the stirring rate during filtration were examined. Stirred filtrations were performed at increasing TMP so as to characterise flux behaviour and retention rates. The feasibility of membrane ultrafiltration for this application was proved since the results of the 10kDa membrane showed the highest expectable retention rates (>99.6%) given the analytical methods used, and steady permeability results [30–40Lh−1m−2bar−1] independently of TMP and filtration course. Moreover, performance was shown to be sustainable as fouling was mostly reversible (>90%), being removable by simple membrane surface rinsing with ultrapure water. This was confirmed by the reconstruction of fouling mechanisms for both membranes. Unstirred and constant TMP 40, 80 and 200kPa filtration experiments were run to study fouling phenomena and the filtration cake characteristics (compressibility and porosity). Two distinct fouling mechanisms were highlighted: the 100kDa membrane underwent internal and sometimes irreversible fouling in the form of pore clogging before cake filtration, while the 10kDa membrane was characterised by filtration cake only. This work proposes solutions for the predicament of nanoparticle release into the environment and opens up perspectives for efficient wastewater treatment in the context of their industrial development.

Ecotoxicological and chemical evaluation of phenolic compounds in industrial effluents

The aim of this paper was to evaluate the ecotoxicological response of industrial effluents containing phenolic compounds. All complex effluents collected from a chemical plant and then after both a chemical–physical and biological treatment were characterised with chemical analysis, biodegradability tests and four ecotoxicological tests ( Daphnia magna, Artemia salina, Brachionus plicatilis and Vibrio fisheri with Microtox ®). The evaluation of the chemical and ecotoxicological data was useful for predicting the effect of the raw effluent on the treatment plant and the impact of the final treated effluent on the receiving water. Besides the toxicity of the effluent from the chemical plants, the acute toxicity of its main components was also determined. The results of the tests and toxicity data from literature were transformed in Toxic Units (TUs). Effluent toxicity was under- or over-estimated by calculating the sum of the TUs of the individual components, depending on which toxicity data and test organisms were used.

Effect of Hydraulic Retention Time on Nitrification in an AirLift Biological Reactor

The occurrence of nitrogenous compounds in industrial effluents at concentration levels above legal limits, is a well-known and serious pollution problem for the receiving body. The biological process for the removal of these substances, commonly referred to as ammoniacal nitrogen, is known as nitrification. Bacteria involved are mainly of the genuses Nitrosomonas and Nitrobacter. The aim of the present work was to study the effect of the hydraulic retention time (HRT) on the efficiency of ammonia removal from a petroleum refinery effluent using activated carbon particles as a biofilm support in an airlift bioreactor. The experiments were carried out using HRTs, equal to six, eight and ten hours. The results show that HRT equal to 8 and 10 hours were enough to reduce ammoniacal nitrogen concentration to levels below permited legal limits (5mg/L NH3-N). The reactor nitrifying performance was maximized at 85% removal of ammoniacal nitrogen, for a HRT equal to 10 hours.

Comparison of two strategies for assessing ecotoxicological aspects of complex wastewater from a chemical-pharmaceutical plant

The potential environmental impact of wastewater from a chemical-pharmaceutical plant was evaluated by two different characterization strategies. The aim of the first strategy was to characterize the complex effluent before and after degradation by activated sludge. Chemical analyses (AOX, EOX, DOC, TOC, BOD, CODCr, N-total, N-NH4, N-NO2, N-NO3, P-total, and P-PO4) were performed on the undegraded and the degraded sample. Ecotoxicological tests were performed on the undegraded sample (acute toxicity, Microtox®, inhibition of respiration of activated sludge, inhibition of nitrification of activated sludge) and on the degraded sample (acute toxicity, Microtox). Moreover, the concentration of potentially bioaccu-mulating substances was determined in the degraded sample. The tests were done according to the STORK Project (characterization of persistent organic compounds in industrial effluents) initiated by the Swedish Environmental Protection Agency. The second characterization strategy was concentrated on single substances in the effluent. The amount of all discharged chemicals was estimated using mass-balance calculations or by chemical analysis of the water phase. Ecotoxicological data for several of the substances were drawn from the reference literature. For those without any ecotoxicological information, a limited set of tests was performed (Microtox, octanol/water partition coefficient, biodegradation). All substances were classified on the basis of environmental effects using acute toxicity, biodegradation, and bioaccumulation criteria. The two different characterization strategies were useful when predicting environmental effects of wastewater from a chemical-pharmaceutical plant. From a practical and economical point of view, a stepwise approach including elements from both of the above strategies is recommended. A chemical-oriented strategy (discharged amount and ecotoxicological data for each compound) may be useful as a primary step for sorting out hazardous water phases from harmless ones. For less defined water phases, an extensive characterization program, including chemical analyses, acute toxicity testing, and ecotoxicological parameters, may give valuable information about environmental risks.

The effect of withdrawal of morpholine from the influent and its reinstatement on the performance and microbial ecology of a model activated sludge plant treating a morpholine‐containing influent

An activated sludge plant was established which was capable of treating an influent containing morpholine. When this compound was deleted from the influent the ability of the activated sludge to degrade morpholine was reduced. This reduction took the form of an increase in the length of the lag period before morpholine degradation was detected in a die‐away test from 0 to ca 1000 h. The decreased ability of the activated sludge to degrade morpholine was accounted for by a decline in the specific population of morpholine‐degrading microbes. In this activated sludge all morpholine degraders were Mycobacterium spp. In the absence of morpholine in the influent most mycobacteria in the activated sludge retained their morpholine‐degrading phenotypes. This is despite the fact that some of these organisms can lose this phenotype when grown under non‐selective conditions. These results are discussed in relation to other work on the degradation of morpholine and to problems in the treatment of xenobiotic compounds in industrial effluents.

Gas chromatographic determination of trace amounts of sulfur compounds in industrial effluents.

A method is described for the trace determination of hydrogen sulfide, mercaptans, sulfides, and disulfides in industrial effluents which is based on a combination of head-space analysis with microcoulometry. This method increases the analytical sensitivity 10/sup 2/-10/sup 3/ times without any preliminary concentration of the sample. The factors affecting the precision and sensitivity of the analysis are studied. A simple device is developed permitting injection and gas chromatographic analysis of samples of the solution under study without losses of the compound of interest.