Polycyclic Aromatic Hydrocarbons In Sludge Research Articles

Enhancement of PAHs biodegradation in biosurfactant/phenol system by increasing the bioavailability of PAHs

The poor bioavailability of polycyclic aromatic hydrocarbons (PAHs) is the main limiting factor for their biodegradation in contaminated sites. The addition of biosurfactant is an effective method for enhancing the bioavailability of PAHs. Suitable low molecular weight (LMW) organic matters have been shown to increase the bioavailability of PAHs. Therefore, we investigated the effect of phenol, which often co-exists with PAHs, on the biodegradation of PAHs in biosurfactant solution. The results show that the critical micelle concentration (CMC) of the biosurfactant decreased after phenol was added. The formation of mixed micelles resulted in enhancement of PAHs dissolution. The weight solubilization ratio (WSR) values of biosurfactant for Phe, Pyr and BaP in phenol solution are approximately 1.34, 1.40 and 1.67 times that of the control group, respectively. Phenol, therefore, can assist biosurfactant to increase the availability of PAHs by microbes. The bioavailability of PAHs in sludge increased from 27.7% to 43.1% after the biosurfactant was added, and reached a maximum of 49.2%, following the simultaneous addition of phenol and biosurfactant. Phenol also improved the degradation of PAHs by Stenotrophomonas sp. N5 in biosurfactant solution.

Determination of Polycyclic Aromatic Hydrocarbons in Sludge from Water and Wastewater Treatment Plants by GC-MS.

The qualitative and quantitative analysis of 16 polycyclic aromatic hydrocarbons (PAHs) in sludge samples from drinking water treatment plants (DWTP) and wastewater treatment plants (WWTP) were established using gas chromatography–mass spectrometry (GC-MS). The method was suitable to quantify PAHs in the sludge of DWTP and WWTP and it was confirmed by the relevant quality assurance/quality control (QA/QC) procedures. The recovery of individual PAHs in the spiked samples ranged from 74.3% to 108.7%. Detection limits of the analytical procedure were 0.0010–0.0046 mg/kg dw for individual PAHs. This method was used to determine the concentration of PAHs in the selected two DWTP and four WWTP sludge samples. The results showed that the total PAHs (∑PAHs) were in low levels which ranged from 0.0668 to 0.1357 mg/kg dw, and 0.5342–1.0666 mg/kg dw for DWTP and WWTP respectively. The 3- & 4-ring PAHs were predominant in DWTP sludge, ranging from 77.4% to 82.7%; the 4-ring PAHs were predominant in WWTP sludge, ranging from 40.7% to 47.6%. The PAHs of DWTP sludge are mainly composed of 3-ring phenanthrene and anthracene and 4-ring pyrene, and chrysene. The PAHs of WWTP sludge are dominated by 4-ring fluoranthene, pyrene, and chrysene. The detected PAHs concentration should be undoubtedly considered for agriculture in sludge applications based on the limits of the EU regulations. The results of this study can be used for regular monitoring to establish a reference for sludge management and application to agriculture.

Profile of polycyclic aromatic hydrocarbons in digested sewage sludge

ABSTRACTOne of the methods of sludge disposal in cities is its use as an amendment in adjoining agricultural soil. Contaminants in sludge can, however, nullify the benefits. Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent organic pollutants, if present, can pose health risks by virtue of their carcinogenic potential and persistence in soil. The present study deals with profile analysis of PAHs in digested sewage sludge of a megacity, Delhi. Mean concentration of the sum of 16 PAHs in the sludge from 5 sewage treatment plants (STPs) was 20.67 ± 4.14 mg/kg, dry weight (dw). Carcinogenic PAHs represented ∼47% of the total PAHs. Benzo[g,h,i]perylene recorded the highest mean concentration followed by dibenzo[a,h]anthracene. Low molecular weight PAHs and high molecular weight PAHs contributed 19% and 81% to total PAHs content respectively. Principal component analysis identified the major sources of PAHs in sludge as coal and natural gas combustion. Wood combustion, oil and oil derivatives are the other identified sources. The observed PAH levels in sludge from selected STPs of Delhi were found to violate the limit values proposed by the European Union and the US legislation for application in agriculture.

Organic Contaminants in Chinese Sewage Sludge: A Meta-Analysis of the Literature of the Past 30 Years.

The production of sewage sludge is increasing in China but with unsafe disposal practices, causing potential risk to human health and the environment. Using literature from the past 30 years (N = 159), we conducted a meta-analysis of organic contaminants (OCs) in Chinese sludge. Most data were available from developed and populated regions, and no data were found for Tibet. Since 1987, 35 classes of chemicals consisting of 749 individual compounds and 1 mixture have been analyzed, in which antibiotics and polycyclic aromatic hydrocarbons (PAHs) were the most targeted analytes. For 13 classes of principal OCs (defined as chemicals detected in over five studies) in sludge, the median (expressed in nanograms per gram dry weight) was the highest for phthalate esters (27 900), followed by alkylphenol polyethoxylates (12 000), synthetic musks (5800), antibiotics (4240), PAHs (3490), ultraviolet stabilizers (670), bisphenol analogs (160), organochlorine pesticides (110), polybrominated diphenyl ethers (100), pharmaceuticals (84), hormones (69), perfluorinated compounds (21), and polychlorinated biphenyls (15). Concentrations of PAHs in sludges collected between 1998 and 2012 showed a decreasing trend. Study findings suggest the need for a Chinese national sewage sludge survey to identify and regulate toxic OCs, ideally employing both targeted as well as nontargeted screening approaches.

S189 Effects of Two kinds of Herbage Crops on the Removal of High Molecular Weight Polycyclic Aromatic Hydrocarbons in Sludge

The purpose of this study was to compare the effects of two herbage crops (awnless brome and alfalfa) on the removal of high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) in sludge, including 9 PAHs. The results showed that Awnless brome and alfalfa had similar removal percentages for the total Σ9 HMWPAHs in the sludge, which were 85.75% and 85.08%, respectively. However, these two plants were different in the removal percentages of individual PAHs, for example, awnless brome had higher removal percentages for the 4-ring compounds (Pyr, BaA, Chry, BbF and BKF), while alfalfa showed higher removal percentages for the 5-ring and 6-ring compounds (BaP, DbA, Bghip and InP). The activities of catalase and polyphenol oxidase in the sludge planted with alfalfa were significantly higher than those in the sludge with awnless brome, while the activities of dehydrogenase in these two kinds of sludge were opposite. In conclusion, awnless brome and alfalfa could be directly used for the remediation of HMW-PAHs-polluted sludge, and awnless brome inclined to degrade the HMW-PAHs with 4 rings, while alfalfa tended to degrade the HMW-PAHs with 5 and 6 rings.

Effects of Two kinds of Herbage Crops on the Removal of High Molecular Weight Polycyclic Aromatic Hydrocarbons in Sludge

Effects of Two kinds of Herbage Crops on the Removal of High Molecular Weight Polycyclic Aromatic Hydrocarbons in Sludge

Heavy metals and polycyclic aromatic hydrocarbons in sludge from three industrial wastewater treatment plants of the industrial parks of Isfahan province

Aims: In this study, the characterization of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) were investigated in three different industrial sewage sludges in industrial parks of Isfahan province, Isfahan, Iran. Materials and Methods: Sludge samples were collected from three dry bed wastewater treatment plants (WWTPs) within the province during of four seasons of 2011-2012. Gas chromatography-mass spectrometry and inductively coupled plasma were used to measure PAHs and HMs contents in sludge. Results: The average concentrations of Cd, Cr, Cu, Mo, Ni, Pb, As, Hg, and Se in sewage sludge were 305.67, 514, 1019, 6.46, 102.33, 1181.33, 277.33, 226.83, and 6.35 mg/kg dry weight (d.w.), respectively. The concentrations of HMs in most of the sludge samples were above the regulatory limits for the sludge class 1 and 2 to be used in agriculture in Iran. The levels of ∑8 PAHs varied from 92.33 μg/ the to 257.87 μg/kg d.w. in the sludge, that lower than the limitation value (6 mg/kg) recommended by the Europe Union and US Environmental Protection Agency for land application. Phenanthrene, pyrene, and fluorene were predominant isomers of PAH in sludge samples. The highest value was found in the Morchekhort WWTP. Conclusion: The concentration and composition of PAHs and HMs in sewage sludge varied and depended mainly on the quantity and type of industrial wastewater accepted by the WWTPs. There is a pyrene in sewage samples that is a carcinogenic. The concentration of HMs in sewage sludge was above of standard levels. Finally, we are not recommended the using of industrial sewage sludge in agriculture because of the high value of HMs was found in samples.

Investigation into the distribution of polycyclic aromatic hydrocarbons (PAHs) in wastewater sewage sludge and its resulting pyrolysis bio-oils

This study firstly investigated the distributions of 16 US EPA priority controlled polycyclic aromatic hydrocarbons (PAHs) in seven kinds of different wastewater sewage sludges and bio-oils from the sludge pyrolysis. A lab-scale tube furnace was used to simulate sludge pyrolysis and retrieve condensed oils. PAH determination was conducted with the extraction, concentration, and purification of PAHs in sludge samples and the resulting bio-oils, and then GC-MS analysis. Then, the factors influencing the distributions of different rings of PAHs in pyrolysis bio-oil, such as the chemical characteristics of raw sewage sludge and pyrolysis condition, were analyzed. It was noted that the total amount of PAHs in raw sludge is evidently varied with the sludge resource, with values ranging between 9.19 and 23.68mg/kg. The middle molar weight (MMW) PAH distribution is dominant. PAH concentrations in sludge pyrolysis bio-oil were ranged from 13.72 to 48.9mg/kg. The most abundant PAHs were the low molar weight (LMW) PAHs. It could be found that the concentration of LMW PAHs in bio-oil is correlated with MMW PAHs in raw sewage sludge at best, which the correlation coefficient is 0.607. For MMW and HMW (high molar weight) PAHs, they are significantly correlated with HMW PAHs in raw sewage sludge, which the correlation coefficients are 0.672 and 0.580, respectively. The concentration of LMW PAHs in bio-oil is also relatively significant and correlated with the volatile matter content of raw sludge. In addition, it was proved that final temperature and residence time have important influences on PAH generations during the pyrolysis of sewage sludge.

Migration of polycyclic aromatic hydrocarbons (PAHs) in urban treatment sludge to the air during PAH removal applications

In the present study, the amounts of polycylic aromatic hydrocarbons (PAHs) penetrating into air during PAH removal applications from the urban treatment sludge were investigated. The effects of the temperature, photocatalyst type, and dose on the PAH removal efficiencies and PAH evaporation were explained. The sludge samples were taken from an urban wastewater treatment plant located in the city of Bursa, with 585,000 equivalent population. The ultraviolet C (UV-C) light of 254 nm wavelength was used within the UV applications performed on a specially designed setup. Internal air of the setup was vacuumed through polyurethane foam (PUF) columns in order to collect the evaporated PAHs from the sludge during the PAH removal applications. All experiments were performed with three repetitions. The PAH concentrations were measured by gas chromatography–mass spectrometry (GC-MS). It was observed that the amounts of PAHs penetrating into the air were increased with increase of temperature, and more than 80% of PAHs migrated to the air consisted of 3-ring compounds during the UV and UV-diethylamine (DEA) experiments at 38 and 53 °C. It was determined that 40% decrease was ensured in Σ12 (total of 12) PAH amounts with UV application and 13% of PAHs in sludge penetrated into the air. In the UV-TiO2 applications, a maximum 80% of Σ12 PAH removal was obtained by adding 0.5% TiO2 of dry weight of sludge. The quantity of PAH penetrating into air did not exceed 15%. UV-TiO2 applications ensured high levels of PAH removal in the sludge and also reduced the quantity of PAH penetrating into the air. Within the scope of the samples added with DEA, there was no increase in PAH removal efficiencies and the penetration of PAHs into air was not decreased. In light of these data, it was concluded that UV-TiO2 application is the most suitable PAH removal alternative that restricts the convection of PAH pollution.Implications: Polycyclic aromatic hydrocarbon (PAH) evaporation rates from sludge samples obtained from an urban wastewater treatment plant were investigated here for the first time by employing removal applications. TiO2 and diethylamine were used as photocatalysts in this study. A special device was designed and successfully used in this study. Treatment sludge can be a significant source of PAHs for the atmosphere. The data highlight the need for removal of PAHs in treatment sludge via methods limiting their evaporation to the air. It was observed that UV-TiO2 application was the most suitable PAH removal alternative that restricts the convection of PAH pollution.

Occurrence of polycyclic aromatic hydrocarbons in sludges from different stages of a wastewater treatment plant in Italy

The occurrence of polycyclic aromatic hydrocarbons (PAHs) in various sludge types from a moderate-big wastewater treatment plant in the Lombardy region, Italy, was studied. Pyrene was continuously the most abundant PAH, whereas anthracene was the PAH with the lowest concentrations. Average ΣPAH concentrations ranged between 2405 ng/g (dry weight) in the secondary sludge and 2645 ng/g (dry weight) in the final sludge. A mass balance estimation between the various sludges showed no evident degradation of PAHs. The final sludge PAH concentrations were constantly at around half of the maximum permissible limit set by the European Union for use of sewage sludge in agriculture (6 mg/kg). The highest PAH concentrations were observed during the summer periods. Finally, two approaches were used to estimate the raw wastewater concentrations based on the sludge PAH concentrations. The values obtained did not differ much from the average concentrations measured at the influent wastewaters.

The Effect of pH Value on the Polycyclic Aromatic Hydrocarbons Degradation in Sludge during Biological Aerobic Fermentation Process

The degradation of polycyclic aromatic hydrocarbons in sludge in aerobic fermentation process is affected by many factors, and the pile body pH value is one of the important factors. Through the test of mixing lime pile body regulating pH value (7.7, 8.2, 9), the polycyclic aromatic hydrocarbon degradation effect was researched under the different pH conditions and the same of the other aerobic fermentation conditions. The results showed that, pH=7.7 test device (not mixing lime ) on PAHs degradation effect was best, worst was the pH=8.2 test device, the sludge degradation of the polycyclic aromatic hydrocarbons effect is negative effect.

Levels and distribution of synthetic musks and polycyclic aromatic hydrocarbons in sludge collected from Guangdong Province

The levels and distribution of six polycyclic musks, three nitromusks and 15 polycyclic aromatic hydrocarbons (PAHs) were investigated in sludge collected from 19 municipal wastewater treatment plants (WWTPs) in six cities in Guangdong Province, China. PAHs were detected in all of the sludge samples, and the levels of the total 15 PAHs ranged from 177.2–4421.8 μg/kg dry weight (dw). Four polycyclic musks, 4-acetyl-1,1-dimethyl-6-tert-butylindan (ADBI), 6-acetyl-1,1,2,3,3,5-hexamethylindan (AHMI), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta (g) -2-benzopyran (HHCB) and 7-acetyl -1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydro naphthalene (AHTN), were found in these samples. The total concentrations of polycyclic musks varied from 794.4–12960.3 μg/kg dw, with HHCB and AHTN being the main components. Of the three nitromusks, 2,6-dinitro-3-methoxy-4-tert- butyl - toluene (MA) was only found in one sludge sample at the limit of detection (LOD) level, while 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (Musk xylene, MX) and 4-acetyl-1-tert-butyl-3,5-dimethyl-2,6-dinitrobenzene (Musk ketone, MK) were found at levels ranging from the LOD to 65.8 μg/kg dw and LOD to 172.7 μg/kg dw, respectively, in most of the sludge samples. The PAHs, polycyclic musks and nitro musks were also shown to have various distribution patterns, possibly due to their different wastewater sources and wastewater treatment technology.

Heavy Metals and PAHs in Sewage Sludge from Twelve Wastewater Treatment Plants in Zhejiang Province

To investigate the heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in sludge of twelve wastewater treatment plants (WWTPs) in Zhejiang province of China, and to assess their potential for land application. Sludge was collected from 12 WWTPs within the province. GC-MS and AAS were used to measure PAHs and HMs contents in sludge. Concentrations of HMs in most of the sludge samples were below the regulatory limits for the sludge to be used in agriculture in China with the exception of Zn in 2 sludge samples and Cd in 1 sample. All 16 PAHs, targeted by the USEPA agency, were found in the sludge from the twelve plants with a total concentration ranging from 33.73 mg kg(-1) to 82.58 mg kg(-1) (dry weight, d.w.). The levels of Sigma9 PAHs varied from 13.87 mg kg(-1) to 61.86 mg kg(-1) (d.w.) in the sludge, far exceeding the limitation value recommended by the Europe Union. The concentration and composition of PAHs in sewage sludge varied and depended mainly on the quantity and type of industrial wastewater accepted by the WWTPs. A significant relationship between the proportion of industrial wastewater received by WWTPs and the total content of 16 PAHs in the sludge was observed. PAHs have become one of the primary pollutants in sludge of Zhejiang WWTPs instead of HMs. It is, therefore, essential to reduce the contents of PAHs before the sludge can be used in agriculture through proper treatment.

Effect of Composting on Polycyclic Aromatic Hydrocarbons Removal in Sewage Sludge

Changes in the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) identified by the US Environmental Protection Agency as priority pollutants were investigated during the composting process of sewage sludge mixed with rapeseed marc (9:1, weight base). Results showed that total PAHs concentrations of the sludge sampled in different seasons had far exceeded the accepted Europe Union cut-off limits for land application. Phenanthrene, fluorene and dibenz(a, h) anthracene were dominant PAHs in the sludge, accounting for 62.8~69.6% of the total amount of the 16 PAHs. Composting appeared to be an effective method for the removal of PAHs in sewage sludge. After 50 days of composting, a significant reduction of concentration of the total PAHs was detected as compared with the initial concentration in composting material. The significant relationship between the biodegradation of organic matter and the losses of Σ16 PAHs during composting indicated that microbial degradation was the key process responsible for the efficient removal of PAHs from the sludge. Among all tested PAHs, fluorene was the most recalcitrant and became the primary residual PAH in the composted material. The lower removal rate of fluorene during composting was a limiting factor for the potential land application of the sludge. Further studies are needed to enhance the removal of fluorene in order to achieve a safe utilization of this sludge.

Contamination of PAHs in Sludge Samples from the Yangtze River Delta Area

To ascertain the contaminated conditions of polycyclic aromatic hydrocarbons (PAHs) in sludge and to evaluate the risk of application of this sludge for agricultural purposes, 44 sludge samples obtained from 15 cities in the Yangtze River Delta area of China were investigated using capillary gas chromatography/mass spectrometry (GC/MS) after ultrasonic extraction and silica gel cleanup. PAHs' contents ranged from 0.0167 to 15.4860 mg kg −1 (dry weight, DW) and averaged 1.376 mg kg −1, with most samples containing < 1.5 mg kg −1. Pyrene (PY), fluoranthene (FL), benzo[b]fluoranthene (BbF), indeno[1,2,3-cd]pyrene (IND), benzo[a]pyrene (B[a]P), and benzo[g,h,i]perylene (BghiP) were the most dominant compounds, ranging from 0.1582 to 0.2518 mg kg −1. Single PAH, such as naphthalene (NAP, 2-benzene rings), phenan-threne (PA, 3-benzene rings), PY (4-benzene rings), and FL (3-benzene rings), had high detection rates (76.1%–93.5%). The distribution patterns of PAHs were found to vary with the sludge samples; however, the patterns showed that a few compounds with 2- and 3-benzene rings were commonly found in the samples, whereas those with 4-, 5-, and 6-benzene rings were usually less commonly found. All the 44 sludge samples were within the B[a]P concentration limit for sludge applied to agricultural land in China (< 3.0 mg kg −1). The probable sources of PAH contamination in the sludge samples were petroleum, petroleum products, and combustion of liquid and solid fuel. The concentrations and distributions of the 16 PAHs in sludge were related to sludge type, source, and treatment technology, together with the physicochemical properties.

Biodegradation of polycyclic aromatic hydrocarbons in sludge.

Biodegradation of polycyclic aromatic hydrocarbons in sludge.

Determination of petroleum hydrocarbons and polycyclic aromatic hydrocarbons in sludge from wastewater treatment basins.

Screening by gas chromatography with flame ionization detection and gas chromatography-mass spectrometry has been carried out on sludge extracts of wastewater treatment basins. Soxhlet extraction with trichlorotrifluoroethane was applied. The yields for petroleum hydrocarbons and PAH recovery were high, usually in excess of 90%. The proposed investigations permit a quick assessment of petroleum pollutants in the environment.