Oxidation by Fenton's reagent combined with biological treatment applied to a creosote-comtaminated soil.

In this study, we investigated the feasibility of using Fenton oxidation to remove sorbed polycyclic aromatic hydrocarbons (PAHs) in aged soil samples with creosote oil from a wood preserving site. The optimal dosage of reagents was determined by a statistical method, the central composite rotatable experimental design. The maximum PAH removal was 80% with a molar ratio of oxidant/catalyst equal to 90:1. In general low molecular weight PAHs (3 rings) were degraded more efficiently than higher molecular weight PAHs (4 and 5 rings). The hydrogen peroxide decomposition kinetic was studied in the presence of KH(2)PO(4) as stabilizer. The kinetic data were fitted to a simple model, the pseudo-first-order which describes the hydrogen peroxide decomposition. The PAH kinetic degradation was also studied, and demonstrated that non-stabilized hydrogen peroxide was consumed in less than 30 min, whilst PAH removal continued for up to 24h. In a second part of the work, a combined chemical and biological treatment of the soil was carried out and shown to be dependent on the pre-oxidation step. Different reagent doses (H(2)O(2):Fe) were used (10, 20, 40, 60:1) in the pre-treatment step. An excess of hydrogen peroxide resulted in a poor biological removal, thus the optimal molar ratio of H(2)O(2):Fe for the combined process was 20:1. The combined treatment resulted in a maximum total PAH removal of 75% with a 30% increase in removal due to the biodegradation step. The sample with highest PAH removal in the pre-oxidation step led to no further increase in removal by biological treatment. This suggests that the more aggressive chemical pre-oxidation does not favour biological treatment. The physico-chemical properties of the pollutants were an important factor in the PAH removal as they influenced chemical, biological and combined treatments.

Elimination of pharmaceuticals in sewage treatment plants in Finland.

The occurrence of eight pharmaceuticals (beta-blockers: acebutolol, atenolol, metoprolol and sotalol; antiepileptic: carbamazepine; fluoroquinolone antibiotics: ciprofloxacin, norfloxacin, ofloxacin) were assessed in the raw and treated sewage of 12 sewage treatment plants (STPs) in Finland. The average concentrations in the raw and treated sewage ranged from 100 to 1060 ng L(-1) and from <24 to 755 ng L(-1), respectively. The average daily loads ranged from 36 to 405 mg/1000 inh and from 2 to 302 mg/1000 inh, respectively. In the treatment plants, fluoroquinolones were eliminated by >80%. Carbamazepine was not eliminated during the treatment and in fact even higher concentrations were frequently found in the treated than in the raw sewages. The increase in concentration was shown to be most likely due to enzymatic cleavage of the glucuronic conjugate of carbamazepine and release of the parent compound in the treatment plant. The beta-blockers were eliminated in average by less than 65% and the elimination varied greatly between the treatment plants. Especially the dilution of raw sewage by rainwater and a consequent decrease in the hydraulic retention time of a treatment plant was found to deteriorate the elimination of the beta-blockers. The work shows that especially carbamazepine and the beta-blockers may reach the recipient waters and there is a need to enhance their elimination in the sewage treatment plants. In this attempt, a denitrifying biofilter as a tertiary treatment could be of minor importance since in this study it did not result in further elimination of the target compounds.

The role of ozonation and activated carbon filtration in the natural organic matter removal from drinking water.

Aquatic natural organic matter is one of the most important problems in the drinking water treatment process design and development. In this study, the removal of the natural organic matter was followed both in the full-scale drinking water treatment process and in the pilot-scale studies. The full-scale process consisted of coagulation, flocculation and flotation, sand filtration, ozonation, activated carbon filtration and disinfection. The aim of the pilot study was to investigate the influence of the dose and contact time of ozonation, and also the impact of activated carbon filtration, on the removal efficiency of organic matter. Several methods, including high-performance size-exclusion chromatography, total organic carbon content and assimilable organic carbon content measurements were used to characterize the behaviour of organic matter and its removal efficiency. On the full-scale process, total organic carbon was removed by over 90 %. According to size-exclusion measurements, chemical coagulation removed the high molar mass organic matter with an efficiency of 98%. The ozonation further removed the smaller molar mass fraction compounds by about 27%, while residual higher molar mass matter remained quite unaltered. Activated carbon filtration removed primarily intermediate and low molar mass organic matter. In the pilot-tests, conducted with sand filtered water from the full-scale process, it was noticed, that the ozonation removed primarily smaller organic compounds. The amount of assimilable organic carbon increased with increasing ozone dose, up to 0.4 mg l(-1) with the highest ozone dose of 4.0 mg 1(-1). The activated carbon filtration removed the assimilable organic carbon. Total organic carbon content was not reduced in ozonation.

Removal of pharmaceuticals in drinking water treatment: effect of chemical coagulation.

The removal of selected pharmaceuticals (diclofenac, ibuprofen, bezafibrate, carbamazepine and sulfamethoxazole) by chemical coagulation was studied. Jar test experiments were done in MilliQ water, in lake water and in commercial humic acid solutions using aluminium (pH 6) and ferric sulphate (pH 4.5). The concentrations of the pharmaceuticals in the studied water samples were determined by HPLC analysis and UV detection. In MilliQ water coagulation, the pharmaceuticals were poorly removed (< 10%) with the exception of diclofenac, which was removed up to 66% with ferric sulphate. This compound was also the only pharmaceutical removed (30%) during the lake water coagulation with ferric sulphate. In the presence of dissolved humic matter, diclofenac as well as ibuprofen and bezafibrate could be removed by ferric sulphate coagulation. The removal of diclofenac reached a maximum of 77%, while 50% of ibuprofen and 36% of bezafibrate were removed. Hence, a high amount of high-molecular-weight dissolved organic matter enhanced the removal of ionisable pharmaceuticals. The non-ionisable compounds, carbamazepine and sulfamethoxazole, were not affected by the coagulation processes studied. Although conditions such as high humic material content, low coagulation pH and ferric coagulant increase the removal of certain ionic pharmaceuticals, it can be concluded that by coagulation it is not possible to entirely remove pharmaceuticals from water.

Effect of modified Fenton's reaction on microbial activity and removal of PAHs in creosote oil contaminated soil.

This study describes the removal of polycyclic aromatic hydrocarbons (PAHs) from creosote oil contaminated soil by modified Fenton's reaction in laboratory-scale column experiments and subsequent aerobic biodegradation of PAHs by indigenous bacteria during incubation of the soil. The effect of hydrogen peroxide addition for 4 and 10 days and saturation of soil with H(2)O(2) on was studied. In both experiments the H(2)O(2) dosage was 0.4 g H(2)O(2)/g soil. In completely H(2)O(2)-saturated soil the removal of PAHs (44% within 4 days) by modified Fenton reaction was uniform over the entire soil column. In non-uniformly saturated soil, PAH removal was higher in completely saturated soil (52% in 10 days) compared to partially saturated soil, with only 25% in 10 days. The effect of the modified Fenton's reaction on the microbial activity in the soil was assessed based on toxicity tests towards Vibrio fischeri, enumeration of viable and dead cells, microbial extracellular enzyme activity, and oxygen consumption and carbon dioxide production during soil incubation. During the laboratory-scale column experiments, the toxicity of column leachate towards Vibrio fischeri increased as a result of the modified Fenton's reaction. The activities of the microbial extracellular enzymes acetate- and acidic phosphomono-esterase were lower in the incubated modified Fenton's treated soil compared to extracellular enzyme activities in untreated soil. Abundance of viable cells was lower in incubated modified Fenton treated soil than in untreated soil. Incubation of soil in serum bottles at 20 degrees C resulted in consumption of oxygen and formation of carbon dioxide, indicating aerobic biodegradation of organic compounds. In untreated soil 20-30% of the PAHs were biodegraded during 2 months of incubation. Incubation of chemically treated soil slightly increased PAH-removal compared to PAH-removal in untreated soil.

Comparison of the effiency of aluminium and ferric sulphate in the removal of natural organic matter during drinking water treatment process.

The removal of natural organic matter by coagulation in the drinking water treatment train was studied for a period of two years. In the middle of the study, the coagulation/flotation process was modified by replacing the aluminium sulphate by ferric sulphate. At the same time, the filtration unit was enhanced by adding a sand filter unit before the activated carbon filtration and by changing new carbons on to the activated carbon filters. A special aim was to compare the efficiency of the aluminium and ferric coagulants in the organic matter removal by several methods, including high-performance size-exclusion chromatography. A comparison of quantity and characteristics of organic matter in treated water before and after treatment process modification provided an insight into process performance. Approximately 95% of high molar mass organic substances were removed in the process with both coagulation agents. The greatest difference between the coagulants occurred in the removal of organic matter having molar masses of 1000-4000 g mol(-1). These intermediate molar mass organic compounds were removed 25% more efficiently with iron-based coagulant than with aluminium-based. Low molar mass material was poorly removed regardless of the coagulant. On average, only 10% of this fraction was removed. According to different measuring techniques used in the study, the ferric sulphate coagulation was 10% more efficient in the overall organic matter removal compared to the aluminium sulphate coagulation. Turbidity removal was more efficient with aluminium than with ferric sulphate. Turbidity even increased during winter in ferric sulphate coagulation. However, turbidity was effectively removed in filtrations.

Aged chlorophenol contaminated soil's integrated treatment by ozonation, soil washing and biological methods.

Traditionally soils contaminated by organic compounds have been treated by biological methods, but aged contaminated soils usually contain refractory and toxic compounds not any more responsive to biological treatment. By oxidation and soil washing the biodegradability and bioavailability of these otherwise recalcitrant compounds can be enhanced. The aim of the study was to optimize and integrate soil washing, ozonation (+ hydrogen peroxide) and biological treatment for the remediation of old saw mill soil contaminated by chlorophenols (CPs). The integration of different treatment train variables and the alternation of pHs (3, 7 and 10) and different ozone doses were studied in a laboratory scale. The soil was heavily contaminated aged soil (> 4000 mgCP kg(-1)), so more than 99% of removal should be attained in order to reach the Finnish guideline values. All the individual methods studied were able to degrade/transfer 25 - 95% of the CPs from the soil matrix. By biological treatment only 25% of the CPs were degraded. After soil washing, 40- 80% of the contaminants were transferred from the soil phase and by ozonation 35 - 95% decrease of CPs were achieved. All the methods studied successfully enhanced the biodegradability of the target compound. After biological treatment of ozonated and washed samples even 93 - 100% degradation of CPs was obtained. The most effective treatment was the combination of soil washing + ozonation (in pH 10) followed by biological treatment.

Enhancement of the natural organic matter removal from drinking water by nanofiltration.

Finnish surface waters are abundant in natural organic matter. Natural organic matter can be removed from drinking water in a water treatment process by coagulation and filtration. The standard treatment operations are not able to remove the smallest molar mass fraction of organic matter and the intermediate molar mass matter is only partly removed. The removal of residual natural organic matter from drinking water by nanofiltration was evalueted in this study. Three different nanofiltration membranes were compared in filtering six pre-treated surface waters. The total organic carbon content of the feed waters varied from 2.0 to 4.2 mg l(-1). Other water quality parameters measured were conductivity, alkalinity, hardness, UV-absorbance, SUVA, E2/E3 value and molecular size distribution by high-performance size-exclusion chromatography. The natural organic matter removal efficiencies of the membranes were good and varied between 100% and 49%, and between 85% and 47% according to molecular size distribution and total organic carbon measurements, respectively. Removal of different molecular size fractions varied from 100% to 56%, 100% to 54% and 88% to 19%, regarding high molar mass, intermediate molar mass and low molar mass organic matter, respectively. The Desal-5 DL membrane produced the highest natural organic matter removals.

Photodegradation of ethylenediaminetetraacetic acid (EDTA) and ethylenediamine disuccinic acid (EDDS) within natural UV radiation range.

The rate of photodegradation of two chelating agents, ethylenediaminetetraacetic acid (EDTA) and an isomeric mixture of ethylenediamine disuccinic acid (EDDS), was analysed in humic lake water and in distilled water using exposure to sunlight, and in the laboratory using lamps emitting UV radiation in the range 315-400 nm. Degradation was studied using Fe(III) complexes and sodium salts of chelates. Fe(III) complexes were illuminated at pH 3.1 and 6.5. The results demonstrated that the rate of photodegradation of Fe(III)-EDTA and Fe(III)-EDDS complexes seems to be pH dependent. In the laboratory experiments degradation occurred much faster when the original pH was 3.1 rather than 6.5. The photodegradation of the isomeric mixture of EDDS was markedly faster than the degradation of EDTA both in the laboratory and field experiments, and both in humic and distilled water. The results indicated that in natural waters photodegradation of EDDS is independent of initial speciation of EDDS, while degradation of EDTA is dependent on its existence as Fe(III)-EDTA species.

Use of olive oil for soil extraction and ultraviolet degradation of polychlorinated dibenzo-p-dioxins and dibenzofurans.

This paper represents a successful laboratory-scale photolysis of soil-bound tetra- to octachlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in olive oil. The irradiation source consisted of two blacklight lamps emitting light at a near-ultraviolet range. Samples used in the experiments included pure 1,2,3,4,6,7,8-heptachlorodibenzofuran, PCDD/F extract made of a wood preservative (chlorophenol product Ky 5), and soil that was highly contaminated with PCDD/Fs. Degradation of 1,2,3,4,6,7,8-heptachlorodibenzofuran dissolved in olive oil proceeded rapidlywith a first-order reaction half-life of 13 min. Irradiation of a soil sample resulted in an 84% reduction in PCDD/F toxicity equivalent (I-TEQ) in 17.5 h. A more complete degradation of soil-bound PCDD/Fs was achieved after extraction of the soil with olive oil. The oil was effective in solubilizing PCDD/Fs. After one extraction at room temperature, only 9% of I-TEQ remained in soil. Irradiation of the resulting extract reduced toxicity of the extract by 99%, and even the highly chlorinated congeners octachlorodibenzo-p-dioxin and octachlorodibenzofuran degraded easily (97 and 99% degradation, respectively). Photodegradation byproducts found included diphenyl ether and small amounts of dechlorination products, which were mainly nontoxic PCDD/Fs. Degradation was probably mediated by light absorption of unsaturated fatty acids and phenolic compounds in olive oil, leading to sensitized photolysis of PCDD/Fs.