Sludge Extracts Research Articles

Effect of dissolved organic matter on mobility and activation of chlorotoluron in soil and wheat

Chlorotoluron is a pesticide that is moderately absorbed and fairly mobile and leaching in soils. Dissolved organic matter (DOM) plays a critical role in affecting the environmental behavior of pesticides. In this study, we report the effect of DOM extracted from sludge (SL) and straw (ST) on chlorotoluron sorption/desorption and mobility using several techniques including batch experiment, soil column, soil thin-layer chromatography and bioefficacy estimation. Application of DOM (SL and ST) at 50 and 150 mg DOC L − 1 decreased the sorption of and increased desorption of chlorotoluron in soils. Freundlich constant K f values (sorption) of chlorotoluron for SL1 (50 mg DOC L − 1 sludge extract) and SL2 (150 mg DOC L − 1 sludge extract) treatments were 0.06 and 0.04, respectively, which were significantly lower than the value (0.29) for the control. The respective values for treatments of ST1 (50 mg DOC L − 1 straw extract) and ST2 (150 mg DOC L − 1 straw extract) were 0.04 and 0.02. Mobility of chlorotoluron was tested in packed soil columns and soil plate. Addition of DOM to both systems significantly increased the mobility of chlorotoluron and the total concentration of chlorotoluron in the leachate in columns. Biological analysis with wheat plant revealed that application of DOM reduced the chlorotoluron accumulation in tissues at lower concentration of chlorotoluron and increased its accumulation at higher level of chlorotoluron. Finally, we analyzed FT-IR spectral and fluorescence for DOMs and found that more unsaturated components and amine were present in DOM-ST than in DOM-SL. These results may help our understanding of the general role of DOMs in regulating the activation and mobility of organic chemicals ( e.g. herbicide and contaminants) in the ecosystem.

Protein extraction from activated sludge: An analytical approach

To investigate the efficiency of different methods on exopolymeric substance (EPS) extraction, mechanical and chemical treatments were applied on two activated sludges, regarding the yield of protein extraction as well as their compatibility with usual quantification methods. Mechanical disruption methods do not drastically affect protein measurements by both bicinchoninic acid (BCA) and modified Lowry methods. Chemical compounds such as cationic exchange resin and triton show high interference with modified Lowry method while the protein quantification by BCA method is not affected. In addition, inner sludge compounds were shown to interfere with both methods: BCA and modified Lowry measurement respectively overestimate and underestimate protein content. According to these data, BCA method was chosen in this study as the most appropriate protein quantification method in sludge extracts. Comparison of various extraction protocols, combining mechanical and/or chemical treatments, shows that efficiency can be increased by repeating the same method or by applying a prior mechanical treatment. Proteins are preferably extracted by triton treatments, indicating the importance of hydrophobic interactions linking proteins to the EPS matrix. The amount of extracted proteins reaches 182 and 148 mg eq. BSA g −1 VSS using triton/triton and ultraturax/triton extractions, respectively. Protease activity/extracted protein ratios vary widely depending on extraction protocols. Protease seemed to be preferably extracted by ultrasound and triton treatments (150–220 U mg −1 protein). This study underlines that the choice of a relevant coupled quantification/extraction method is of great importance for efficient EPS determination.

Glyphosate and AMPA Analysis in Sewage Sludge by LC-ESI-MS/MS after FMOC Derivatization on Strong Anion-Exchange Resin as Solid Support

An innovative analytical method has been developed for the determination of glyphosate and aminomethylphosphonic acid (AMPA), its major metabolite, in sewage sludge. This method involved an alkaline extraction from sludge and purification on a strong anion-exchange resin. While the analytes remained fixed by ionic interactions, an "on-solid support" derivatization by FMOC-Cl was carried out. This versatile approach allowed a 10 min reaction and simple elimination of the excess of reagent. The resulting derivatives remained retained by ionic and hydrophobic interactions with the resin until being eluted by a mixed NaCl water/acetonitrile, 70/30, v/v, solution. After an appropriate dilution and adjustment of the pH, the sample was concentrated on an Oasis HLB solid-phase cartridge. For quality analysis of traces in complex matrixes, LC-ESI-MS/MS in the multiple reaction monitoring positive mode was used fulfilling the European Union requirements (Decision 2002/657/CE). To overcome the matrix effects, stable isotopically labeled standards were added to the sludge extracts as internal standards and were thus derivatized during the procedure in parallel to the analytes. Mean recovery values were 70% +/- 7% for glyphosate and 63% +/- 3% for AMPA. Limits of detection (20 and 30 ppb dw) and limits of quantification (35 and 50 ppb dw) for glyphosate and AMPA, respectively, were sufficient to monitor samples taken from Ile-de-France wastewater treatment plants where contamination currently reached 0.1-3 ppm and 2-35 ppm dw for glyphosate and AMPA, respectively.

The Genotoxicity of Priority Polycyclic Aromatic Hydrocarbons (PAHs) Containing Sludge Samples

ABSTRACTIn this research work we developed in vitro tests utilizing mammalian cell cultures, which can rapidly assess effect of exposure of oily sludge-derived chemicals on human and ecological health. Many of these are hazardous to health and environment due to their toxicity and/or accumulation potential in sediments as well as in organisms. Petroleum refinery and petrochemical industry-derived oily sludges contain toxic polycyclic aromatic hydrocarbons (PAHs), some of which are lipophilic in nature. Risk assessment of environmental samples suffers from inadequate availability of toxicity data, lack of knowledge about behavior of genotoxic substances in complex matrices, paucity of information on synergistic and antagonistic interactions of mixture of components, etc.; the literature describing the behavior of genotoxic substances in complex mixtures is sparse and sometimes contradictory. The present study aims at assessing the genotoxic potential of oily sludges collected from an integrated petroleum refinery and petrochemical industry located in the southwestern part of India and a petrochemical industry located in the western part of India using a battery of genotoxicity assays such as DNA damage/strand break, chromosomal aberration, p53 protein induction, and apoptosis in CHO-K1 cell culture system.Exposure with different dose levels of sludge extracts (25, 50, 100 μL) in CHO-K1 cells could cause statistically significant level of (P < 0.001) DNA damage, chromosomal aberration, p53 protein induction, and apoptosis in comparison to negative control treatment groups, and the genotoxicity was attributed to PAHs present in the sludge as identified by GC-MS. This implies that the sludges are genotoxic in nature in mammalian cells tested, and the exposure to these may pose a potential genotoxic risk to human beings.

Dyeing, fastness, and deodorizing properties of cotton, silk, and wool fabrics dyed with coffee sludge (Coffea arabica L.) extract

AbstractA natural colorant was extracted from Coffea arabica L., using water as extractant at 90°C for 90 min. Studies have been made on the dyeing, color fastness, and deodorization properties of cotton, silk, and wool fabrics dyed with Coffea arabica L. extract solutions. The best mordants were found to be FeSO4, CuSO4, and SnSO4 for improving the color strength (K/S) of cotton, silk, and wool fabrics. Mordants MnSO4, ZnSO4, and NiSO4 for cotton (Rating 3), and all mordants except MnSO4 for silk (Rating 3), mordants CuSO4, FeSO4, CoSO4, Al2(SO4)3, and MnSO4 for wool (Rating 4) were the best mordants to improve the light fastness. It was found that FeSO4 and CuSO4 were the best mordants for the improvements of color strength (K/S) and light fastness for silk and wool fabrics. In addition, it was found that cotton, silk, and wool fabrics dyed with the Coffea arabica L. extract showed good deodorization performance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 251–257, 2007

The elimination of the endocrine disrupters 4-nonylphenol and bisphenol A during wastewater treatment - Comparison of conventional and membrane assisted biological wastewater treatment followed by an ozone treatment

A conventional biological wastewater treatment plant (BWWTP) and a membrane bio-reactor (MBR) were operated to treat municipal wastewater. The endocrine disrupting compounds (EDCs), 4-nonylphenol (4-NP) and bisphenol A (BPA; 2,2-bis-(4-hydroxyphenyl)-propane), were spiked into the feed. Additionally, the effluents were treated with ozone (O3). The elimination efficiencies of both treatment techniques and the advanced effluent treatment applying ozone were balanced over a three-week testing period by monitoring 4-NP and BPA concentrations in the feed, all effluents and excess sewage sludge. Reduction of Chemical Oxygen Demand (COD) was observed with 95 ± 2%. Substance specific analyses were performed by gas chromatography, coupled with mass spectrometry (GC-MS). Aqueous samples and sludge extracts after pressurised liquid extraction (PLE) were examined after derivatization using acetic anhydride. The spiking levels into the feed were adjusted to reach concentrations of 51.2 ± 10.1 µg/L (4-NP) and 50.7 ± 8.2 µg/L (BPA), while the effluent samples were fortified prior to ozone treatment by adding 48 µg/L or 49 µg/L of 4-NP and BPA. The elimination achieved without applying ozone were &amp;gt; 98 or 97.8 % for 4-NP and BPA in MBR treatment and &amp;gt; 98 and 91.6 % under conventional treatment. Balances proved biodegradation as the superior elimination mechanism for 4-NP and BPA in both treatment processes

Ecotoxicity, phytotoxicity and extractability of heavy metals from different stabilised sewage sludges

The presence of heavy metals in the sludges produced in wastewater treatment plants restricts their use for agricultural purposes. This study compares different types of sludges (aerobic, anaerobic, unstabilised and sludge from a waste stabilisation pond) in order to assess the extractability of heavy metals using simple extraction, water and DTPA. The stabilisation treatment undergone by the sludges influenced the heavy metals extractability. The least mineralised sludges (unstabilised and aerobic) showed higher metal extractability. The sewage sludges were subjected to chemical characterisation and toxicity testing (ecotoxicity and phytotoxicity assays) in absence of substrate, to provide a preliminary assessment of their suitability for land application. The ecotoxicity assays confirmed that no sludge constituted a hazardous waste. The sludge extracts had significant adverse effect on the germination index (GI) of barley ( Hordeum vulgare L.) and cress ( Lepidium sativum L.), a fact which indicates that some characteristics affected root growth.

Fractionation of heavy metals in sludge from anaerobic wastewater stabilization ponds in southern Spain

The analysis of heavy metals is a very important task to assess the potential environmental and health risk associated with the sludge coming from wastewater treatment plants (WWTPs). However, it is necessary to apply sequential extraction techniques to obtain suitable information about their bioavailability or toxicity. In this paper, a sequential extraction scheme according to the Standard, Measurements and Testing Programme of the European Commission was applied to sludge samples collected from ten anaerobic wastewater stabilization ponds (WSPs) located in southern Spain. Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Ti and Zn were determined in the sludge extracts by inductively coupled plasma atomic emission spectrometry. In relation to current international legislation for the use of sludge for agricultural purposes, none of the metal concentrations exceeded maximum permitted levels. Overall, heavy metals were mainly associated with the two less-available fractions (34% oxidizable metal and 55% residual metal). Only Mn and Zn showed the highest share of the available (exchangeable and reducible) fractions (25–48%).

해양생태독성평가를 위한 표준시험생물로서의 식물플랑크톤에 관한 연구

A series of experiments was conducted to identify the potential of five phytoplankton species as standard test species for marine ecotoxicological tests. The candidate phytoplankton species are Skeletonema costatum, Heterosigma akashiwo, Prorocentrum micans, Isochrysis galbana, and Tetraselmis suecica. Salinity tolerance and sensitivity on potassium dichromate as a reference material were identified. Toxicity of eleven ocean dumped sewage sludges and four red tide expellent extracts were estimated by the inhibition of population growth rates (PGR) of marine diatom S. costatum, While most species revealed relatively weak tolerance on salinity, T. suecica demonstrated the highest salinity tolerance ranged from <TEX>$5\~35$</TEX> psu and the others <TEX>$15\~35$</TEX> psu. H. akashiwo revealed the highest sensitivity as 72h <TEX>$IC_{50}$</TEX>=0.76mg/L and T. suecica the lowest as 72h <TEX>$IC_{50}$</TEX>=8.89mg/L on potassium dichromate. Sludge extracts from industrial waste, domestic sewage and livestock farm waste sludge showed high toxicity as 72h <TEX>$IC_{50}$</TEX><<TEX>$2\%$</TEX> and lowest toxicity from filtration bed sludge as 72h <TEX>$IC_{50}$</TEX>=<TEX>$30.50\%$</TEX> NOEC (No Observed Effective Concentration) of sludge extract ranged from <<TEX>$0.4\%$</TEX> to <TEX>$1.6\%$</TEX> and this indicated high phytotoxicity of ocean dumped sewage sludge. The test sensitivity of phytoplankton PGR inhibition was much higher than those of marine rotifer Brachionus plicatilis mortality test and bioluminescent inhibition test by marine bacteria Vibrio fischeri, and comparable with the sea urchin (Strongylocentrotus intermedius) fertilization test. As a result the phytotoxicity test using phytoplankton PGR inhibition (<TEX>$IC_{50}$</TEX>) must be a useful tool for marine phyto-toxicological evaluation of ocean dumped materials.

Determination of sixteen polycyclic aromatic hydrocarbons in aqueous and solid samples from an Italian wastewater treatment plant

A robust procedure for the determination of 16 US EPA PAHs in both aqueous (e.g. wastewaters, industrial discharges, treated effluents) and solid samples (e.g. suspended solids and sludge) from a wastewater treatment plant (WWTP) is presented. Recovery experiments using different percentages of organic modifier, sorbents and eluting solvent mixtures were carried out in Milli-Q water (1000 mL) spiked with a mixture of the PAH analytes (100 ng/L of each analyte). The solid phase extraction (SPE) procedures applied to spiked waste water samples (1000 mL; 100 ng/L spiking level) permitted simultaneous recovery of all the 16 PAHs with yields >70% (6–13% RSD). SPE clean up procedures applied to sewage and stabilized sludge extracts, showed percent recoveries in the range 73–92% (7–13% RSD) and 71–89% (7–12% RSD), respectively. The methods were used for the determination of PAHs in aqueous and solid samples from the WWTP of Fusina (Venice, Italy). Mean concentrations, as the sum of the 16 PAHs in aqueous and suspended solid samples, were found to be approx. in the 1.12–4.62 μg/L range. Sewage and stabilized sludge samples contained mean PAH concentrations, as sum of 16 compounds, in the concentration range of 1.44–1.26 mg/kg, respectively. Extraction and clean up procedures for sludge samples were validated using EPA certified reference material IRM-104 (CRM No. 912). Instrumental analyses were performed by coupling HPLC with UV-diode array detection (UV-DAD) and fluorescence detection (FLD).

Heavy metal speciation and phytotoxic effects of three representative sewage sludges for agricultural uses

The environmental impact of sewage sludges depends on the availability and phytotoxicity of their heavy metal. The influence of representative sludges (dewatered anaerobic, pelletization, and composted sludge) on the availability of heavy metals, and their effects on seed germination were compared. The total heavy metal concentrations were below the maximum permitted for land-applied waste and the differences among them were small. The DTPA-extracted metal concentrations were rather different. The sequential extraction of the compost showed a slight increase in Cd and Cu availability, and a decrease in the availability of Fe, Mn, Ni and Zn. Pelletization increased the availability of Ni and slightly reduced that of Cr. The dewatering sludge led to greater availability of Cr and Mn but reduced the concentration of Cd. The three different sludges also affected seed germination and root elongation in different ways. The most serious adverse effects were caused by the dewatered sludge extract.

Ecotoxicological evaluation of sewage sludge using bioluminescent marine bacteria and rotifer

Bioassay using the marine bacteria,Vibrio fischeri and rotifer,Brachionus plicatilis, and chemical analyses were conducted to assess the toxicity of the various sewage sludges, one of the major ocean dumped materials in the Yellow Sea of Korea. Sludge elutriates extracted by filtered seawater were used to estimate the ecotoxicity of the sludge. Chemical characterization included the analyses of organic contents, heavy metals, and persistent organic pollutants in sludge. Bacterial bioluminescent inhibition (15 min), rotifer mortality (24 hr) and rotifer population growth inhibition (48 hr) assay were conducted to estimate the sludge toxicity. EC50 15 min (inhibition concentration of bioluminescence after 15 minutes exposed) values by Microtox® bioassay clearly revealed different toxicity levels depending on the sludge sources. Highest toxicity for the bacteria was found with the sludge extract from dyeing waste and followed by industrial waste, livestock waste, and leather processing waste. Clear toxic effects on the bacteria were not found in the sludge extract from filtration bed sludge and rural sewage sludge. Consistent with Microtox® results, rotifer neonate mortality and population growth inhibition test also showed highest toxicity in dyeing waste and low in filtration bed and rural sewage sludge. High concentrations of persistent organic pollutants (POPs) and heavy metals were measured in the samples from the industrial wastes, leather processing plant waste sludge, and urban sewage sludge. However, there was no significant correlation between pollutant concentration levels and the toxicity values of the sludge. This suggests that the ecotoxicity in addition to the chemical analyses of various sludge samples must be estimated before release of potential harmful waste in the natural environment as part of an ecological risk assessment.

Long-term effects of metal-containing farmyard manure and sewage sludge on soil organic matter in a fluvisol

Our aim was to establish the long-term effects of repeated applications after 20 y of organic amendments (farmyard manure at 10 t ha −1 y −1, and urban sewage sludge at two different rates, 10 t ha −1 y −1 and 100 t ha −1 every 2 y) on the quality of a sandy and poorly buffered soil (Fluvisol, pH 6). Chemical characteristics and biodegradability of the labile organic matter, which is mainly derived from microbial biomass and biodegradation products of organic residues, were chosen as indicators for soil quality. The organic C content had reached a maximal value (30.6 g C kg −1 in the 100 t sludge-treated soil), i.e. about 2.5 times that in the control. Six years after the last application, the organic C content and the microbial biomass content remained higher in sludge-treated soils than in the control. In contrast, the proportion of labile organic matter was significantly lower in sludge-treated soils than in manure-treated and control soils. The labile organic matter of sludge extracts appeared less humified than that of manure-treated and control soils.

Application of solid-phase extraction to determination of polycyclic aromatic hydrocarbons in sewage sludge extracts

The study presents the efficiency of sewage sludge sample clean-up with the application of SPE columns with various types of adsorbents. Six columns were tested: C8-octyl, C18 PolarPlus, C18-octadecyl, silicagel (SG), phenyl, cyano. The highest efficiency of recovery was observed for C18-octadecyl. Then, using C18, the method was optimised by changing the following parameters: eluent type and volume, column drying and effect of washing of cartridge.

Optimization and validation of a new method of analysis for polycyclic aromatic hydrocarbons in sewage sludge by liquid chromatography after microwave assisted extraction

Characterization of sludge from waste water treatment plants which are destined to be spread on agricultural lands, is a priority need. Inorganic pollutants are regularly controlled but organic pollutants have received little attention up to now. In this paper, we have developed an analytical procedure using microwave-assisted extraction prior to liquid chromatography coupled with diode array (LC-DAD) or fluorescence (LC-FL) detectors for the determination of polycyclic aromatic hydrocarbons (PAHs) in sewage sludge. The main factors affecting the extraction efficiency (microwave power, irradiation time and extractant volume) were optimized. Clean-up of sewage sludge extracts was not found to be necessary. For adequate fluorescence detection of PAHs a temporal program of excitation and emission wavelengths was used. The optimized method was applied to the extraction of PAHs from various sludges from a waste water treatment plant (Jerez de la Frontera, Cadiz, Spain). The limits of detection were between 4 ng g −1 sewage sludge for benzo[b]fluoranthene and 12 ng g −1 sewage sludge for pyrene using LC-FL. When LC-DAD is used the limits of detection were between 13 ng g −1 for indeno[1,2,3-cd]pyrene and 62 ng g −1 for naphthalene. The relative standard deviations were found to be <10%. The validation of the proposed method was carried out by application to analysis for PAHs in a certified reference material (CRM) 088 dried sewage sludge of the Community Bureau of Reference (BCR). The recoveries were between 69% for benzo[k]fluoranthene and 110% for pyrene using LC-FL and between 52% for indeno[1,2,3-cd]pyrene and 104% for benzo[a]pyrene using LC-DAD of the certified values. These results are in a very good agreement with those given in the literature.

Phytotoxicity and heavy metals speciation of stabilised sewage sludges

The presence of heavy metals in the sludges produced in wastewater treatment restricts plants growth and hence their use for agricultural purposes. This study looks at different types of sludges (aerobic, anaerobic, unstabilised and sludge from a waste stabilisation pond) and compares the distribution of the heavy metals that they contain according to the treatment that they have undergone. The sewage sludges were subjected to chemical characterisation and phytotoxicity testing (in absence of substrate) to provide a preliminary assessment of their suitability for land application. In addition, the total quantity of metals (Cd, Cr, Cu, Ca, K, Fe, Mg, Ni, Na, Pb and Zn) was determined. The Community Bureau of Reference (BCR) method for heavy metal speciation was followed. It was confirmed that the total concentration of heavy metals did not exceed the limits set out by European legislation and that the stabilisation treatment undergone by the sludges strongly influenced the heavy metal distribution and the phases to which they were associated. The sludge extracts did not exert any significant adverse effect on the relative seed germination (RSG) of barley ( Hordeum vulgare L.) or cress ( Lepidium sativum L.), although the reduction in germination index (GI) indicates that some characteristics existed did have an adverse effect on root growth.

Activity of bacteria strains originaited from sewage sludge against some soil fungi

The potential biological activity of three bacterial strains against the four phytopathogens was examined. The bacterial strains were originated from sewage sludge water extract and from the humic acid solution obtained from the sewage sludge. The fresh bacteria cultures and filtered culture broth were used. The noncoated sugar beet seeds were coated by soaking for 15 min in the liquid culture of bacteria, then they were sown in the sterilized soil inoculated by one of the following types of soil fungus: Aphanomyces cochlioides L3, Phoma betas PH8, Pythium irregulare PIR4, Rhizoctonia solani Z10-2. The test proved that Bacillus amytoliquefaciens O1 / O3 and Flaviomonas oryzihabitans K1 / K2 showed antifungal activity on the artificial medium, but they were not able to effectively suppress fungal pathogens in the soil. The bacteria did not injure sugar beet roots, so they can be regarded as microorganisms that are not harmful to plants. It may be concluded that these bacteria have the potential to support antifungal activity of the humis acid and the sewage sludge extracts.

Estimation of polycyclic aromatic hydrocarbons emission from sewage sludge of sewerage treatment plants in Korea

Polycyclic aromatic hydrocarbons (PAHs) are an important group of organic contaminants present in sewage sludge, due to their persistence, toxic, bioaccumulative and long range transfer. These characters make themselves as Persistent Organic Pollutants(POPs) in Long Range Transboundary Air Pollutions convention(LRTAP) of Europe. A method of the gas chromatographicmass spectrometric (GCMS) determination of PAHs present in sewage sludge was developed and applied to analyzed samples from five sewerage treatment plants (SWTPs), having different treatment types. PAHs were extracted from freeze-dried samples by toluene 16 hours in a soxhlet extraction system. The sludge extracts were cleaned-up by an activated silica gel column chromatography. The sum of the 16 US Environmental Protection Agency PAHs sewage sludge samples varied from 2.44 to 4.82 /g. Concentration of emission carcinogen PAHs(PAHcarc), such as Benzo(a)anthracene, Benzo(b)f1uoranthene, Benzo(k)f1uoranthene, Benzo(a)pyrene, Dibenzo(a,h)anthracene and Indeno( 1,2,3-cd)pyrene ranged from 0.62 to 1.03 /g. The total amount of PAHs emission from sewage sludge in Korea was calculated as a top-down approach. PAHs and PAHcarc from sewage treatment plants had emitted to environment by several pathway. The highest amount of emission to the environment was remarked in the ocean dumping(PAHs and PAHcarc emissions were 1155.95 kg/year and 5040.32 kg/year, respectively).

Measurement of glutathione in activated sludges

Thermal, electric, mechanical or oxidative stress seem a promising way to reduce the production of excess activated sludge during biological wastewater treatment. However, the adaptation and the resistance of the sludge microbial ecosystem to stress conditions is a major question as it may definitively limit the effect of some treatments. Defence mechanisms developed by aerobic organisms, in particular, in response to oxidative stress involve various antioxidant activities and compounds such as glutathione. An HPLC method was developed for measuring reduced and total glutathione (GSH and GSHt) in perchloric acid sludge extracts. The method was sensitive, highly specific and validated for linearity, precision and recovery. Considering the extraction yield and the oxidation of GSH during extract storage, the measured GSH concentration was estimated to represent 60% of the GSH content from activated sludges. GSHt ranged from 0.32 to 3.34 μmol g −1 volatile solids and the GSH/GSHt ratio ranged from 32% to 91%. Measurements performed on sludges stressed in precise conditions selected to reach a reduction of sludge production showed a decrease of GSH and GSHt concentrations with thermal, mechanical, electric and ozone stress.

Identification of ubiquinones and menaquinones in activated sludge by liquid chromatography–atmospheric pressure chemical ionization mass spectrometry

A sensitive analytical method has been developed for identification of ubiquinones (UQ- n(H x )) and menaquinones (MK- n(H x )) in activated sludge by liquid chromatography–atmospheric pressure chemical ionization mass spectrometry in negative mode (LC-NI-APCI-MS). Extraction and clean-up of samples were carried out on Sep-Pak Plus Silica solid-phase extraction cartridges. Complete separation of quinones was achieved with an ODS analytical column and using isopropyl ether–methanol (17:83, v/v) as the mobile phase. The compositions of ubiquinones and menaquinones were determined directly using combined information on retention time, the molecular ion mass and fragment ion masses. The lowest instrument quantitative detection limits (LOD inst) for UQ-6, UQ-10, and Vitamin K1 were estimated to be 0.4, 4 and 0.12 ng ( S/ N=10) using LC-NI-APCI-MS in SIM mode, and the lowest method detection limits (LOD meth) achieved by spiking experiment were estimated to be 0.2, 2 and 0.06 μg/g for UQ-6, UQ-10 and Vitamin K1, respectively. On the other hand, the LOD inst for UQ-6, UQ-10, and Vitamin K1 were estimated to be 10, 100 and 2 ng ( S/ N=10) using LC-NI-APCI-MS in full-scan mode, and the LOD meth were estimated to be 7, 60 and 1.2 μg/g for UQ-6, UQ-10, and Vitamin K1, respectively. Both LC-NI-APCI-MS and LC–UV/DAD were applied in the analysis of an activated sludge extract. UQ- n ( n=6–10), MK- n ( n=6–10), MK- n(H 2) ( n=7–10), MK- n(H 4) ( n=8–9) and MK-8(H 6) were detected by LC-NI-APCI-MS, while UQ-6, UQ-7, MK-7(H 2), MK-9 and MK-10(H 2) were not found by LC–UV/DAD. These results suggest that LC-NI-APCI-MS is more sensitive than LC–UV/DAD for the analysis of quinones in environmental samples such as sediment, activated sludge and bio-film in biological processes and other aquatic environments.