Improvement of biodegradability of industrial wastewaters by radiation treatment

Summary In order to evaluate the use of gamma-ray treatment as a pretreatment to conventional biological methods, the effects of gamma-irradiation on biodegradability (BOD₅/COD) of textile and pulp wastewaters were investigated. For all wastewaters studied in this work, the efficiency of treatment based on TOC removal was insignificant even at an absorbed dose of 20 kGy. However, the change of biodegradability was noticeable and largely dependent on the chemical property of wastewaters and the absorbed dose of gamma-rays. For textile wastewaters, gamma-ray treatment increased the biodegradability of desizing effluent due to degradation of polymeric sizing agents such as polyvinyl alcohol. Interestingly, the weight-loss showed the highest value of 0.97 at a relatively low dose of 1 kGy. This may be caused by the degradation of less biodegradable ethylene glycol prior to terephthalic acid decomposition. For pulp wastewater, the gamma-ray treatment did not improve the biodegradability of cooking and bleaching of C/D effluents. However, the biodegradability of bleaching E1 and final effluents was abruptly increased up to 5 kGy then slowly decreased as the absorbed dose was increased. The initial increase of biodegradability may be induced by the decomposition of refractory organic compounds such as chlorophenols, which are known to be the main components of bleaching C/D and final effluents.     

Analysis and anaerobic degradation of wool scouring and olive oil mill wastewaters

Summary Two types of fatty industrial wastewaters, wool scouring effluents (WSE) and olive oil mill effluents (OME) were analysed (lipids, phenols and COD), and were then treated anaerobically in laboratory-scale fixed bed filters. Approximately 50% of the organic compounds in both wastewaters was degraded at two days of hydraulic residence time. A higher biogas production was obtained when using OME rather than WSE. This experimental study confirmed that anaerobic digestion can be considered as a roughing treatment in a multi-step process for industrial fatty wastewaters.     

Electrochemical treatment of slaughterhouse and dairy wastewater: Toward making a sustainable process

The industrial processing of meat and dairy production uses large amounts of fresh water, therefore, generates a significant volume of wastewaters. The treatment of these effluents has been performed using different technologies from biological to electrochemical advanced oxidation processes. Under the circular economy concept, the lack of available freshwater resources has increased the interest in reusing wastewater from slaughterhouses, and even in the recovering of by-products.This article reviews the application of electrochemical treatments to slaughterhouse and dairy wastewaters. In addition, an overview of added-value products and energy recovery from these industrial wastewaters is also presented with future perspectives.     

Determination of Trace Levels of Mercury in Effluents and Wastewaters

Concern about mercury pollution of the environment and the inapplicability of natural water methods necessitated development of a procedure for determining parts per billion mercury in effluents and wastewaters containing large amounts of organic matter. The sample is digested with sulfuric and nitric acids to destroy the organic matter, and the ionic mercury is reduced to the elemental state by stannous ion. Then the digestate is aerated with a stream of air to carry the mercury vapor through a heated line into a quartz cell positioned in an atomic absorption spectrophotometer for measurement. Analyses of effluents and aqueous samples gave good recoveries of added mercury. Effluents, wastewaters, water supplies, and aqueous samples secured within manufacturing plants have been analyzed. With minor modification, the procedure has been applied to manufacturing materials such as vinylpyridine, latex, sizing, dyes, caustic, and hydro.     

Determination of Trace Levels of Mercury in Effluents and Wastewaters

Abstract

Concern about mercury pollution of the environment and the inapplicability of natural water methods necessitated development of a procedure for determining parts per billion mercury in effluents and wastewaters containing large amounts of organic matter. The sample is digested with sulfuric and nitric acids to destroy the organic matter, and the ionic mercury is reduced to the elemental state by stannous ion. Then the digestate is aerated with a stream of air to carry the mercury vapor through a heated line into a quartz cell positioned in an atomic absorption spectrophotometer for measurement. Analyses of effluents and aqueous samples gave good recoveries of added mercury. Effluents, wastewaters, water supplies and aqueous samples secured within manufacturing plants have been analyzed. With minor modification, the procedure has been applied to manufacturing materials such as vinylpyri-dine, latex, sizing, dyes, caustic, and hydro.     

Use of nanoparticles for dye adsorption: Review

A very serious problem nowadays is the colored waters and especially the wastewaters from dyeing industries. Many techniques were already applied in order to treat those effluents, but one of the most simple, low-cost, effective, and successful is adsorption. A very promising class of materials used for this purpose is nanoparticles. This review summarizes some very important works of the last years regarding the use of nanoparticles as potential adsorbent materials for dye adsorption (mainly wastewaters). Widely-used models are described and analyzed for finding the best theoretical adsorption capacity (Langmuir, Freundlich, etc.), as well as some kinetic (pseudo-first, -second order, etc.), thermodynamic (free energy Gibbs, enthalpy, entropy), and desorption/regeneration studies are also discussed in details. Moreover, significant factors such as pH, agitation time, temperature, adsorbent dosage, and initial dye concentration are also reported extensively. Based on thermodynamic studies, meta-data analysis was carried out and commented.     

Nanomaterials for electrochemical detection of pollutants in water: A review

The survival of living beings, including humanity, depends on a continuous supply of clean water. However, due to the development of industry, agriculture, and population growth, an increasing number of wastewaters is discarded, and the negative effects of such actions are clear. The first step in solving this situation is the collection and monitoring of pollutants in water bodies to subsequently facilitate their treatment. Nonetheless, traditional sensing techniques are typically laboratory-based, leading to potential diminishment in analysis quality. In this paper, the most recent developments in micro- and nano-electrochemical devices for pollutant detection in wastewater are reviewed. The devices reviewed are based on a variety of electrodes and the sensing of three different categories of pollutants: nutrients and phenolic compounds, heavy metals, and organic matter. From these electrodes, Cu, Co, and Bi showed promise as versatile materials to detect a grand variety of contaminants. Also, the most commonly used material is glassy carbon, present in the detection of all reviewed analytes.     

Preparation and characterization of Sb2O5-doped Ti/RuO2-ZrO2 for dye decolorization by means of active chlorine

Textile industry is one of the major generators of wastewaters containing recalcitrant compounds such as dyes that jeopardize public health and environment. Electro-oxidation is an alternative method for treating recalcitrant compounds, and the key element for efficient degradation is the adequate use of dimensionally stable anode (DSA) electrodes to efficiently generate active chlorine, which degrades dyes contained in effluents into more environment-friendly compounds. This work is thereby aimed at preparing a novel DSA electrode for efficient generation of active chlorine. Two different dimensionally stable anodes (Ti/RuO₂ and Sb₂O₅-doped Ti/RuO₂-ZrO₂) were prepared and then characterized by grazing incidence X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy, which corroborated the presence of RuO₂, ZrO₂, and Sb₂O₅. The comparison of electroactive areas, assessed by chronoamperometry, showed that Zr helps increase the area of the ternary electrode facilitating the formation of active chlorine. Active chlorine formation was further studied by cyclic voltammetry that revealed a reduction peak attributed to chlorine (product of chloride oxidation). Additionally, decolorization of model solutions that simulate textile effluents containing indigo carmine and reactive black 5 in media with and without chlorides was performed. In the chloride-containing medium, decolorization occurred at a faster rate than in the presence of sulfates. Decolorization of carmine indigo and reactive black 5 in the chloride-containing medium took 40 min and 2 h, respectively. In conclusion, the DSA electrode made of Sb₂O₅-doped Ti/RuO₂-ZrO₂ can efficiently generate the active chlorine for degradation of recalcitrant compounds.     

Assessment of the acute toxicity of triclosan and methyl triclosan in wastewater based on the bioluminescence inhibition of Vibrio fischeri

In this work, the contributions of triclosan and its metabolite methyl triclosan to the overall acute toxicity of wastewater were studied using Vibrio fischeri. The protocol used in this paper involved various steps. First, the aquatic toxicities of triclosan and methyl triclosan were determined for standard substances, and the 50% effective concentrations (EC₅₀) were determined for these compounds. Second, the toxic responses to different mixtures of triclosan, methyl triclosan, and surfactants were studied in different water matrices, i.e., Milli-Q water, groundwater and wastewater, in order to evaluate (i) the antagonistic or synergistic effects, and (ii) the influence of the water matrices. Finally, chemical analysis was used in conjunction with the toxicity results in order to assess the aquatic toxicities of triclosan and its derivative in wastewaters. In this study, the toxicities of 45 real samples corresponding to the influents and effluents from eight wastewater treatment works (WWTW) were analyzed. Thirty-one samples were from a wastewater treatment plant (WWTP) equipped with two pilot-scale membrane bioreactors (MBR), and the influent and the effluent samples after various treatments were characterized via different chromatographic approaches, including solid-phase extraction (SPE), liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS), and SPE coupled to gas chromatography–mass spectrometry (GC–MS). The toxicity was determined by measuring the bioluminescence inhibition of Vibrio fischeri. In order to complete the study and to extrapolate the results to different WWTPs, the toxicity to V. fischeri of samples from seven more plants was analyzed, as were their triclosan and methyl triclosan concentrations. Good agreement was established between the overall toxicity values and concentrations of the biocides, indicating that triclosan is one of the major toxic organic pollutants currently found in domestic wastewaters.     

Identification and removal of sulfhydryl groups from wastewaters

Thiols represent a source of environmental pollution especially wastewater. This work proposed to study the elaboration of cellulose acetate polymer-based membranes for their application in the removal of a sulfhydryl groups of real biological treated wastewaters. The addition of nanoparticles to membranes improves the water purification capacity by promoting a good separation of sulfur, more particularly by ZnO-NPs. We used ultrafiltration membrane-assisted ZnO and TiO₂ NPs application on real effluents from different biological treatment plants. We identified the hydrosulfite (thiol) group in wastewater and we used membrane processes ultrafiltration technique for sulfur removal. We evaluated the degradation of sulfur in biological treatment plants in Tunisia: The urban wastewater treatment plant or the conventional plant of Rades Malienne is a secondary biological wastewater treatment plant noted STEP1. The rural wastewater treatment plant based vertical flow planted with Phragmites australis from the Grombalia region noted STEP2 and rural wastewater treatment plant based horizontal flow planted with Phragmites australis from the Grombalia region noted STEP3. STEP1 is found to be more loaded with sulfur. Application of AC-ZnO membrane gives 99.07% and 99.55% of sulfur removal from wastewater of STEP1 and STEP3. STEP3 is 50 times less charged on sulfur than STEP1. We suggested that when the sulfur content is high, this leads to an increase in mineral elements. This could be explained by the interactions between thiols and the major elements that cause mineral pollution.     

Occurrence of cytostatic compounds in hospital effluents and wastewaters,determined by liquid chromatography coupled to high-resolution mass spectrometry

The occurrence of 26 commonly used cytostatic compounds in wastewaters was evaluated using an automated solid-phase extraction (SPE) method with liquid chromatography–high-resolution mass spectrometry (LC–HRMS). Detection was optimized using Oasis HLB SPE cartridges at pH 2. Two hospital effluents and their two receiving wastewater treatment plants were sampled over five days. In hospital effluents, eight cytostatics were detected at levels up to 86.2 μg L^?1 for ifosfamide, 4.72 μg L^?1 for cyclophosphamide, and 0.73 μg L^?1 for irinotecan, the three most relevant compounds identified. Cyclophosphamide and megestrol acetate were found in wastewaters at concentrations up to 0.22 μg L^?1 for the latter. The predicted environmental concentrations (PEC) in sewage effluents of ifosfamide (2.4–4.3 ng L^?1), capecitabine (11.5–14.2 ng L^?1), and irinotecan (0.4–0.6 ng L^?1), calculated from consumption data in each hospital, published excretion values for the target compounds, and wastewater elimination rates, were in agreement with experimental values.     

Comparative studies of the leachate of an industrial landfill by gas chromatography-mass spectrometry, liquid chromatography-nuclear magnetic resonance and liquid chromatography-mass spectrometry

Nowadays, the need to have a realistic characterization of industrial effluents in the environment has become more and more recognized. A palette of different analytical methods both for sample extraction and instrumental analysis are available today, some older, others introduced more recently. The aim of this research is to compare a number of these techniques. To do this we studied a real leachate from an industrial landfill and carried out chemical analyses for organic pollutants, using different extraction methods based on solid-phase extraction and solid-phase microextraction and different instrumental techniques such as GC-MS, LC-MS, NMR and LC-NMR. Results show the performances of the different techniques, which are complementary.     

Ti/TiO2 indicator electrodes formed by plasma electrolytic oxidation for potentiometric analysis

Ti/TiO₂ indicator electrodes were prepared by plasma electrolytic oxidation (PEO) method in the tetraborate electrolyte and were used for potentiometric indication of chemical reactions of different types and for analysis of surface and industrial wastewaters on the example of potentiometric determination of alkalinity and chloride. The electrodes formed at current densities of 0.05, 0.1, 0.15 and 0.2 A/cm² are different in composition, surface morphology and electroanalytical properties. The electrodes formed at a current density of 0.05 A/cm² exhibit the highest pH-sensitivity and generate the highest analytical signal at the equivalence point in the acid–base and precipitation titrations. The maximum analytical signal at the equivalence point, exceeding in magnitude the analytical signal, obtained by classical Pt electrode in oxidation–reduction and complexometric titrations generates PEO layers formed at a current density of 0.05 A/cm² and a platinum-modified nanoparticles. The results of the potentiometric titration of the surface and technogenic waters using as indicator Ti/TiO₂ electrodes are comparable with the conventionally used glass electrode (to determine alkalinity) and Ag electrode (to the determine chloride) and the results of visual titration. The advantage of the obtained metal oxide systems is the ability to determine two hydrochemical parameters due to their multifunctionality and opportunity to work with a single electrode. In addition, these sensors offer some analytical characteristics such as sensitivity, good reproducibility, high mechanical stability and a simple preparation procedure.     

Electrochemical regeneration of sulfur loaded electrodes

Electrochemical oxidation of sulfide is a promising technique for its removal from wastewaters. Generally, the main product of this oxidation reaction is elemental sulfur. The latter deposits as a solid on the electrode and deactivates it. Therefore, an efficient and effective regeneration technique of sulfur loaded electrodes is required for the practical implementation of this technology. Here we demonstrate a method for in situ reduction of electrodeposited sulfur on carbon fibre electrodes to sulfide/polysulfides, at low energy input. The intermediary coulombic efficiency (CE) values strongly depend on pH and buffer capacity of the solution. These values were recorded up to 435 ± 5% due to simultaneous chemical dissolution of sulfur to polysulfides under alkaline conditions. This process demonstrates the potential for continuously removing dissolved sulfide from wastewaters at an anode as sulfur and recovering the deposited sulfur based on regular switching between anodic sulfide oxidation and cathodic sulfur reduction.     

Screen-printed multienzyme arrays for use in amperometric batch and flow systems

Screen-printing technology for electrode fabrication enables construction of amperometric devices suitable for combination of several enzyme electrodes. To develop a biosensor array for characterisation of wastewaters, tyrosinase and horseradish peroxidase (HRP) or cholinesterase-modified electrodes were combined on the same array. The behaviour of the tyrosinase-modified electrode in the presence of hydrogen peroxide (required co-substrate for the HRP-modified electrode) and acetylthiocholine chloride (required co-substrate for cholinesterase) was studied. Performance of bi-enzyme biosensor arrays in the batch mode and in the flow-injection system are discussed.     

Applicability of nanofiltration and reverse osmosis for the treatment of wastewater of different origin

Membrane separations are finding greater use in wastewater treatment because of their efficiency. In order to prove the effectiveness of membrane filtration an applicability study is carried out. Nanofiltration and reverse osmosis membranes are tested under quite different conditions to reduce the chemical oxygen demands (COD) of wastewaters to meet the Council Directive 76/464/EEC release limit. Two kinds of real wastewaters were selected for the investigation. The wastewaters represent extreme different circumstances since the difference between their COD is two orders of magnitude. All of the membranes tested can be applied either to the treatment of wastewater of high COD (pharmaceutical wastewater) or wastewater of low COD (dumpsite leachate), since the different conditions do not change the membrane characteristics. The experimental data show that none of the membranes can decrease the COD to the release limit in one step. However, if two-stage filtrations (nanofiltration followed by reverse osmosis) are accomplished for both of the wastewaters, a total COD reduction of 94% can be achieved. With the application of the two-stage filtration the COD of the wastewater of low COD can be decreased below the release limit but in case of wastewater of the high COD further treatment will be required.      

Biotreatment of tannin-rich beer-factory wastewater with white-rot basidiomycete Coriolopsis gallica monitored by pyrolysis/gas chromatography/mass spectrometry

Some fractions of beer-factory wastewaters represent an important environmental concern owing to their high content of polyphenols and dark-brown color. The capacity of Coriolopsis gallica to preferentially degrade lignin has been successfully applied in our laboratory to the biotreatment and decolorization of paper-industry effluents. In this work, the ability of this white-rot fungus to degrade high-tannin-containing wastewaters is evaluated. Under all the conditions studied, effluent decolorization and chemical oxygen demand reduction achieved by C. gallica at day 12 of incubation were close to 50 and 65%, respectively. No adhesion of dark color to the fungal mycelium was observed suggesting that decolorization could be ascribed to C. gallica degradation systems. Mycelium dry-weight values showed that C. gallica is tolerant to relatively high tannin content present in the effluent samples. In the sample containing the highest effluent concentration (60% v/v), dry-weight values suggested an inhibition of fungal growth at day 6 of incubation and a further adaptation of the fungus to the stressing tannin effect at day 12 of fungal treatment. Pyrolysis/gas chromatography/mass spectrometry results showed a decrease of polyphenols pyrolysis products, mainly phenol and guaiacol, with the incubation time. All these results indicate the potential use of C. gallica in bioremediation of tannin-containing industrial wastewaters and in other applications where a reduction in polyphenols content is required.     

Stereoisomer quantification of the beta-blocker drugs atenolol, metoprolol, and propranolol in wastewaters by chiral high-performance liquid chromatography-tandem mass spectrometry

A chiral liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) method was developed and validated for measuring individual enantiomers of three beta-blocker drugs (atenolol, metoprolol, and propranolol) in wastewater treatment plant (WWTP) influents and effluents. Mean recoveries of the pharmaceuticals ranged from 67 to 106%, and the limits of detection of the analytes were 2-17 ng/L in wastewater effluents. The method was demonstrated by measuring, for the first time, the stereoisomer composition of target analytes in raw and treated wastewaters of two Canadian WWTPs. In these trials, racemic amounts of the three drugs were observed in influent of one wastewater treatment plant, but nonracemic amounts were observed in another. Effluents of the two plants contained nonracemic amounts of the drugs. These results indicate that biologically-mediated stereoselective processes that differ among WWTPs had occurred to eliminate individual enantiomers of the target analytes.     

Direct Electrooxidation of Ascorbic Acid at the Nanocrystaline Graphite‐like Pyrolytic Carbon Film Electrode

Pyrolytic carbon films (PCFs) were prepared by chemical vapor deposition (CVD) at different deposition temperatures. As an example of using PCF electrode in electroanalysis, the direct electrooxidation of ascorbic acid (AA) at the PCF electrode was investigated and compared with common carbon‐based electrodes such as glassy carbon (GC), edge plane pyrolytic graphite (EPPG), and basal plane pyrolytic graphite (BPPG) electrodes. It was found that the PCF electrodes prepared under deposition temperatures higher than 1050 °C showed a higher sensitivity and lower overpotential compared to the other carbon electrodes. The electrode was successfully applied for determination of AA in real samples.     

Functional stability of a mixed microbial consortium producing PHA from waste carbon sources

Polyhydroxyalkanoates (PHAs) represent an environmentally effective alternative to synthetic thermoplastics; however, current production practices are not sustainable. In this study, PHA production was accomplished in sequencing batch bioreactors utilizing real wastewaters and mixed microbial consortia from municipal activated sludge as inoculum. Polymer production reached 85, 53, and 10% of the cell dry weight from methanol-enriched pulp and paper mill foul condensate, fermented municipal primary solids, and biodiesel wastewater, respectively. Using denaturing gradient gel electrophoresis of 16S-rDNA from polymerase chain reaction-amplified DNA extracts, distinctly different communities were observed between and within wastewaters following enrichment. Most importantly, functional stability was maintained despite differing and contrasting microbial populations.