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Olive mill wastewater (OMW) evaporation ponds management was investigated in five serial evaporation open-air multiponds of 50 ha located in Sfax (Tunisia). Physico-chemical parameters and microbial flora evolution were considered. Empirical models describing the OMW characteristic changes with the operation time were established and Principal Component Analysis (PCA) described the correlation between physico-chemical and biological parameters. COD, BOD, total solids, polyphenols and electrical conductivity exhibited first-order models. Four groups exhibited high correlations. The first included temperature, density, COD, TSS, TS, BOD, VS, TOC, TKN, polyphenols and minerals. The second group was made up of yeasts and moulds. The third group was established with phenolic compounds, total sugars, fats, total phosphorous, NH(4)(+) and pH. The fourth group was constituted by exclusively aerobic bacteria. Bacterial-growth toxic effect was exhibited by high organic load, ash content and polyphenols, whereas moulds and yeasts were more adapted to OMW. During the storage, all the third group parameter values decreased and were inversely related to the others. In the last pond, COD, BOD, TS and TSS rates were reduced by 40%, 50%, 50% and 75% respectively. The evaporation and the biological activity were the main processes acting, predicting the OMW behavior during evaporation in air-open ponds.
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PMID:Olive mill wastewater evaporation management using PCA method Case study of natural degradation in stabilization ponds (Sfax, Tunisia). 2003 54

A mixture of six phenolic acids, corresponding to an initial TOC of 370 mgC/L, was studied by Fenton's peroxidation aiming to improve the biodegradability of agro-industrial wastewaters. Input operating variables including the concentration of pollutants, iron and hydrogen peroxide as well as the reaction time were used to assess the mineralization degree through a factorial experimental methodology. A TOC removal in the range of 15.0-58.8% was attained within the operational conditions used. A reduced model was achieved using the statistically important independent factors and interactions to predict TOC degradation. On the hydrogen peroxide injection methodology, the results showed that the continuous introduction of small volumes is advantageous when compared with one single addition of the overall volume at the zero reaction time with a mineralization improvement of 11%. The use of FeSO(4).7H(2)O correspondent to a Fe(2+) load of 271 mg; [H(2)O(2)]=488.0 mM, injected in twelve aliquots each 30 min during 6h of reaction reached optimal efficiencies with the parent compounds (quantified by HPLC and the Folin-Ciocalteau method) quickly totally removed and TOC, COD and BOD(5) final values of 123 mgC/L, 180 mgO(2)/L and 146 mgO(2)/L, respectively. Toxicity assessment by Vibrio fischeri light inhibition revealed that Fenton's process reduces the effluent ecological impact related with the decomposition of the toxic phenolic acids. Indeed, EC(50) changed from 32.2% dilution to no-dilution needed. The analysis of BOD(5)/COD ratio pointed out a high improvement of the treated wastewater biodegradability from 0.30 to 0.80 meaning that the application of Fenton's oxidation as a pre-treatment enables a further application of an efficient post-biological technology which was also confirmed by respirometry.
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PMID:Fenton's oxidation process for phenolic wastewater remediation and biodegradability enhancement. 2047 38

This study investigates changes in waste microbial community composition and biomass during in situ aeration in laboratory-scale columns over 32 weeks. Microbial profiles were assessed in solid and leachate samples in relation to physical-chemical parameters using phospholipid ester linked fatty acid (PLFA) and phospholipid ether lipid (PLEL) analysis and parameters such as pH, EC, TC, TOC, TN, NO(3)(-), NH(4)(+), COD and the biochemical parameter BOD(5). Principal component analysis (PCA) of the individual PLFAs and PLELs indicated a change in community composition and biomass over the operation period, which could be differentiated in the three phases (i) anaerobic, (ii) aeration start and (iii) extended aeration. PCA revealed that aeration and pH values were the most influential parameters on microbial dynamics. There was a marked decrease of ubiquitous microorganisms, some Gram negative bacterial groups and methanogenic archaea, but a consecutive increase of Gram positive microbial groups along with a rapid reduction of organics after aeration start. Those in situ aeration effects on microbial community composition and C conversion were stable throughout the laboratory set-up of 32 weeks.
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PMID:Characterisation of microbial communities in relation to physical-chemical parameters during in situ aeration of waste material. 2048 79

The treatment of concentrated landfill leachate rejected from reverse osmosis (RO) with Fenton process was studied, and the system model was developed through the examination of reaction kinetics. The leachate is typically non-biodegradable with low BOD(5)/COD ratio 0.01. The oxidation reactions of Fenton process was found to be a two-stage process, where a fast initial reaction (H(2)O(2)/Fe(2+)) was followed by a much slower one (H(2)O(2)/Fe(3+)). A simple and more accurate mathematics model based on COD and TOC removals has been derived successfully to describe the two-stage reaction kinetics. The two corresponding parameters involved in this model have been identified as the initial reaction rate and the maximum oxidation removal efficiency, respectively. It was found to be very useful for evaluating the performance of Fenton system and/or for process design using the two parameters under different experimental conditions.
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PMID:Mathematical model analysis of Fenton oxidation of landfill leachate. 2094 66

Phytoremediation is a novel and promising approach for the treatment of pollutants. This study did explore the potential of Aster amellus Linn. to decolorize a sulfonated azo dye Remazol Red (RR), a mixture of dyes and a textile effluent. Induction in the activities of lignin peroxidase, tyrosinase, veratryl alcohol oxidase and riboflavin reductase was observed during RR decolorization, suggesting their involvement in the metabolism of RR. UV-Visible absorption spectrum, HPLC and FTIR analysis confirmed the degradation of RR. Four metabolites after the degradation of the dye were identified as 2-[(3-diazenylphenyl) sulfonyl] ethanesulfonate, 4-amino-5-hydroxynaphthalene-2,7-disulfonate, naphthalene-2-sulfonate and 3-(1,3,5-triazin-2-ylamino)benzenesulfonate by using GC/MS. Textile effluent and mixture of dyes showed 47% and 62% decrease respectively in American Dye Manufacturers Institute value. BOD of textile effluent and mixture of dyes were reduced by 75% and 48% respectively, COD of industrial effluent and mixture of dyes was reduced by 60% and 75% and TOC was reduced by 54% and 69% respectively after the treatment by A. amellus for 60 h; this indicated that the plant can be used for cleaning textile effluents. Toxicity study revealed the phytotransformation of RR into non-toxic products.
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PMID:The role of Aster amellus Linn. in the degradation of a sulfonated azo dye Remazol Red: a phytoremediation strategy. 2123 39

Little is known about the effect of anaerobic and anoxic stages on the protozoan community in the activated sludge process and how this subsequently affects performance. Using a laboratory-scale BNR system the effect of different periods of anoxia on both the protozoan community and performance efficiency have been examined. Four SBRs were operated at two cycles per day using a range of combined anoxic/anaerobic periods (0, 60, 120 and 200 min). Effluent quality (TOC, BOD, TP, TN, NH(4)-N, NO(3)-N and NO(2)-N), sludge settleability and ciliate community (species diversity and abundance) were analysed over a periods of up to 24 days of operation. The species richness and total abundance of ciliates were found to decrease with longer anoxic/anaerobic periods. Both, positive and negative significant correlations between the abundance of certain species and the period of anoxia was observed (e.g. Opercularia microdiscum, Epicarchesium granulatum), although other species (i.e. Acineria uncinata, Epistylis sp.) were unaffected by exposure to anoxia. In the laboratory-scale units, the 60 min anoxic/anaerobic period resulted in good process performance (TOC and BOD removal of 97-98% respectively), nitrification (80-90%), denitrification (52%) but poor levels of biological P-removal (12%); with the protozoan community moderately affected but still diverse with high abundances. Increasing the length of anoxia to up to 200 min did not enhance denitrification although P-removal rates increased to between 22 and 33%; however, ciliate species richness and total abundance both decreased and sludge settleability became poorer. The study shows that activated sludge ciliate protozoa display a range of tolerances to anoxia that result in altered ciliate communities depending on the length of combined anoxic/anaerobic periods within the treatment process. It is recommended that anoxic/anaerobic periods should be optimised to sustain the protozoan community while achieving maximum performance and nutrient removal.
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PMID:The effect of anoxia and anaerobia on ciliate community in biological nutrient removal systems using laboratory-scale sequencing batch reactors (SBRs). 2132 59

A novel bioelectrochemical reactor with anodic biooxidation coupled to cathodic bioelectro-Fenton was developed for the enhanced treatment of highly concentrated organic wastewater. Using swine wastewater as a model, the anode-cathode coupled system was demonstrated to be both efficient and energy-saving. Without any external energy supply to the system, BOD(5), COD, NH(3)-N and TOC in the wastewater could be greatly reduced at both 1.1g COD L(-1)d(-1) and 4.6g COD L(-1)d(-1) of OLR, with the overall removal rates ranging from 62.2% to 95.7%. Simultaneously, electricity was generated at around 3-8 Wm(-3) of maximum output power density. Based on electron balance calculation, 60-65% of all the electrons produced from anodic biooxidation were consumed in the cathodic bioelectro-Fenton process. This coupled system has a potential for enhanced treatment of high strength wastewater and provides a new way for efficient utilization of the electron generated from biooxidation of organic matters.
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PMID:Coupling of anodic biooxidation and cathodic bioelectro-Fenton for enhanced swine wastewater treatment. 2171 64

Fenton technologies for wastewater treatment have demonstrated their effectiveness in eliminating toxic compounds. This study examines how hydrogen peroxide concentration and ultraviolet (UV) light affects oxidation processes. However, total mineralization through these Fenton technologies is expensive compared with biological technologies. Therefore, partial chemical oxidation of toxic wastewaters with Fenton processes followed by biological units may increase the application range of Fenton technologies. Using 2,6-dimethylaniline (2,6-DMA) as the target compound, this study also investigates oxidation intermediates and their biodegradable efficiencies after treatment by Fenton, electro-Fenton and photoelectron-Fenton processes. Analytical results show that the UV light-promoting efficiency, r(PE-F)/r(E-F), was 2.02, 2.55 and 2.67 with initial hydrogen peroxide concentrations of 15, 20 and 25 mM, respectively. We conclude that UV irradiation promoted 2,6-DMA degradation significantly. The same tendency was observed for biochemical oxygen demand/total organic carbon (BOD(5)/TOC) ratios for each process, meaning that 2,6-DMA can be successfully detoxified using the electro-Fenton and photoelectro-Fenton processes. Some organic intermediates aminobenzene, nitrobenzene, 2,6-dimethylphenol, phenol and oxalic acid--were detected in different oxidation processes.
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PMID:Oxidation of 2,6-dimethylaniline by the Fenton, electro-Fenton and photoelectro-Fenton processes. 2180 52

The aim of this work was to evaluate the use of copper slag to catalyze phenol degradation in water by advanced oxidation processes (AOPs). Copper slag was tested in combination with H(2)O(2) (slag/H(2)O(2)) and H(2)O(2)/UV (slag/H(2)O(2)/UV). The studied methods promoted the complete photocatalytic degradation of phenol. Besides, they were able to reduce about 50% the TOC content in the samples. Slag/H(2)O(2)/UV and slag/H(2)O(2) treatments have favored biodegradability increment along the reaction time. Nevertheless, the irradiated method achieved higher values of the biodegradability indicator (BOD(5)/TOC). The toxicity assessment indicated the formation of more toxic compounds in both treatments. However, the control of the reaction time would minimize the environmental impact of the effluents.
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PMID:Evaluation of copper slag to catalyze advanced oxidation processes for the removal of phenol in water. 2237 Feb 1

In this work, Bi(4)Nb(x)Ta((1-x))O(8)I photocatalysts have been synthesized by solid state reaction method and characterized by powder X-ray diffraction, scanning electron microscope and UV-Vis near infrared diffuse reflectance spectroscopy. The photocatalytic activity of these photocatalysts was evaluated by the degradation of methyl orange (MO) in aqueous solutions under visible light, UV light and solar irradiation. The effects of catalyst dosage, initial pH and MO concentration on the removal efficiency were studied, and the photocatalytic reaction kinetics of MO degradation as well. The results indicated that Bi(4)Nb(x)Ta((1-x))O(8)I exhibited high photocatalytic activity for the removal of MO in aqueous solutions. For example, the removal efficiency of MO by Bi(4)Nb(0.1)Ta(0.9)O(8)I was as high as 92% within 12 h visible light irradiation under the optimal conditions: initial MO concentration of 5-10 mg L(-1), catalyst dosage of 6 g L(-1) and natural pH (6-8), the MO molecules could be completely degradated by Bi(4)Nb(0.1)Ta(0.9)O(8)I within 40 min under UV light irradiation, and the photodegradation efficiency reaches to 60% after 7 h solar irradiation. Furthermore, the photocatalytic degradation of Bisphenol A (BPA) was also investigated under visible light irradiation. It is found that 99% BPA could be mineralized by Bi(4)Nb(0.1)Ta(0.9)O(8)I after 16 h visible light irradiation. Through HPLC/MS, BOD, TOC, UV-Vis measurements, we determined possible degradation products of MO and BPA. The results indicated that MO was degradated into products which are easier to be biodegradable and innocuous treated, and BPA could be mineralized completely. Furthermore, the possibility for the photosensitization effect in the degradation process of MO under visible light irradiation has been excluded.
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PMID:Photocatalytic removal of organic pollutants in aqueous solution by Bi(4)Nb(x)Ta((1-x))O(8)I. 2238 58


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