Fate Of Pentachlorophenol Research Articles

Successive rapid reductive dehalogenation and mineralization of pentachlorophenol by the indigenous microflora of farmyard manure compost.

To determine whether composting with animal manure can be used to effectively remediate soil from a pentachlorophenol (PCP)-contaminated site, and to establish the fate of the degraded xenobiotic. Contaminated soil from a sawmill site was mixed with farm animal manure and composted in a 0.5 m3 silo under fully aerobic conditions. The disappearance and fate of PCP was monitored by gas chromatography (GC-ECD) and extensive mineralization confirmed in experiments with 14C-radiolabelled PCP. The disappearance of PCP was rapid and virtually complete within 6 days, prior to the onset of thermophilic conditions. Dechlorination of the PCP was found to be both reductive and sequential. PCP removal from contaminated soil by aerobic composting with animal manure is efficient and proceeds via reductive dechlorination to virtually complete mineralization. This contrasts with other chlorophenol composting regimes in which mineralization is achieved but dechlorination intermediates do not accumulate to detectable levels. The results of this study demonstrate that anaerobic reductive dechlorination can proceed in an aerobic composting environment and contribute to efficient pentachlorophenol removal. Farmyard manure composts may represent a rapid, low-cost, low-technology option for treatment of chlorophenol-contaminated soils.

Fate of Pentachlorophenol (PCP) in an Anaerobic Digester

To investigate the potential use of an anaerobic digester for treating pentachlorophenol (PCP) wastes in wastewater treatment plants (WWTPs), the fate of PCP in a digester was examined. In this study, two laboratory‐scale anaerobic digesters were operated in parallel. One was dosed with PCP; the other was not and served as a control. Before any PCP addition, the digesters were seeded and fed with digested and raw sludges, respectively, from a local WWTP, then went through a lengthy startup period. When the digesters became stable, their overall performances were similar to the full‐scale digesters located at the WWTP. The fate study of PCP was conducted under steady‐state conditions using two methods: (a) using radioactively labeled 14C PCP and (b) studying mass conservation of added PCP. Steady state was assumed as the similarity of pH, daily digester gas production, and solids data between the PCP‐acclimated and control digesters. The 14C radioactivity, PCP, and chlorophenols were measured in the aqueous, solid, and gaseous phases. From the radioactively labeled PCP study, results showed that approximately 19.5% of 14C PCP was recovered from the aqueous phase, 78% from the solid phase, and 2.5% from gaseous phase. From the mass‐balance study, results indicated that chlorophenols present in the digester effluent contained 95% (molar basis) of 3‐monochlorophenol (16.8% in the aqueous phase), 4.5% of 3,4‐dichlorophenol (0.3%), and 0.5% of 3,5‐dichlorophenol (0.1%). No chlorophenols were detected in the gaseous phase.

Toxicity and fate of pentachlorophenol in anaerobic acidogenic systems

Toxic effects of organic pollutants and their fate in anaerobic acidogenic systems have not been studied extensively despite the potential of acidogenic treatment to be an efficient and economical pretreatment process. The objective of this paper was to study the toxicity and fate of pentachlorophenol (PCP) in an acidogenic, glucose-degrading anaerobic enrichment system. Chemostat cultures (1.5-day SRT) were acclimated to 21–59μM (6–17mg/l) PCP for 159–261days. Up to 121μM (35mg/l) PCP allowed greater than 99.5% influent glucose removal in chemostats, but serum bottle experiments showed that these PCP concentrations partially inhibited glucose degradation. In contrast to the control, the test chemostats with PCP showed formation of lactate and ethanol with lower acetate concentrations. Hydrogen-utilizing methanogens were inhibited by 21–121μM (6–35mg/l) PCP. No biodegradation of PCP was observed even in acclimated cultures. Even with significant removal of PCP in both and serum bottles, chlorophenol intermediates were not found, and batch experiments showed that such chlorophenol intermediates, if formed, would have undergone little degradation. Extraction of PCP in serum bottles showed sorption to biomass was the dominant mechanism for PCP removal in acidogenic cultures. Hence, contrary to expectations, the usefulness of anaerobic acidogenic cultures for degradation of PCP could not be substantiated. Further research on factors stimulating PCP degradation by nonmethanogenic anaerobes is necessary.

Mineralization and conversion of pentachlorophenol (PCP) in soil inoculated with the white-rot fungus Trametes versicolor

The fate of pentachlorophenol (PCP) in autoclaved soil supplemented with straw and inoculated with the white-rot fungus Trametes versicolor was investigated. Inoculated flasks were incubated for 0 to 42 d and control flasks for 0 to 28 d. Mineralization and volatilization of PCP and its transformation products were measured using 14C-labelled PCP for radiorespirometry and extraction analysis, and non-labelled PCP to monitor by use of gas chromatography transformation products of PCP. After incubation soil was extracted with water, dioxane, alkali (KOH–methanol) and the residue was combusted. PCP was analyzed from all extracts and its transformation products were analyzed from both water and dioxane fractions. During 42 d of incubation T. versicolor mineralized 29% of the PCP. The concentration of non-labelled PCP decreased to 4% of its original value during the incubation period. Only trace amounts of anisoles such as pentachloroanisole (PCA) and 2,3,4,6-tetrachloroanisole (2,3,4,6-TeCA) were formed during incubation. Part of the 14C-label was alkali-extractable, indicating that it was bound to humic substances, but this part was apparently later attacked and mineralized by the fungus. Results suggest that the treatment of PCP polluted soils with T. versicolor is a possibility.

Degradation of pentachlorophenol in soil by streptomyces rochei 303

The fate of pentachlorophenol (PCP) in soil under natural conditions was investigated. It was revealed that the total amount of PCP significantly decreased when soil was inoculated by Streptomyces rochei 303, a strain‐destructor of chlorophenols. The products of PCP transformation, such as tetra‐ and trichlorophenols, pentachloro‐benzene, chlorinated dioxins, were identified after the first month of the experiment. Their quantity was less in the variant with the introduced strain compared to control.

Hycrest crested wheatgrass accelerates the degradation of pentachlorophenol in soil.

We investigated the effects of vegetation on the fate of pentachlorophenol (PCP) in soil using a novel high-flow sealed test system. Pentachlorophenol has been widely used as a wood preservative, and this highly toxic biocide contaminates soil and ground water at many sites. Although plants are known to accelerate the rates of degradation of certain soil contaminants, this approach has not been thoroughly investigated for PCP. The fate of [14C]PCP, added to soil at a concentration of 100 mg/kg, was compared in three unplanted and three planted systems. The plant used was Hycrest, a perennial, drought-tolerant cultivar of crested wheatgrass [Agropyron desertorum (Fischer ex Link) Schultes]. The flow-through test system allowed us to maintain a budget for 14C-label as well as monitor mineralization (breakdown to 14CO2) and volatilization of the test compound in a 155-d trial. In the unplanted systems, an average of 88% of the total radiolabel remained in the soil and leachate and only 6% was mineralized. In the planted system, 33% of the radiolabel remained in the soil plus leachate, 22% was mineralized, and 36% was associated with plant tissue (21% with the root fraction and 15% with shoots). Mineralization rates were 23.1 mg PCP mineralized kg-1 soil in 20 wk in the planted system, and for the unplanted system 6.6 mg PCP kg-1 soil for the same time period. Similar amounts of volatile organic material were generated in the two systems (1.5%). Results indicated that establishing crested wheatgrass on PCP-contaminated surface soils may accelerate the removal of the contaminant.

The pH dependent accumulation of PCP in aquatic microcosms with sediment

The fate of pentachlorophenol in aquatic microcosms, consisting of three trophic levels and held under varying conditions of pH and sediment type, was assessed. The pH was set at 4, 6, or 8, with an organic sediment (3% organic carbon) or an inorganic sediment (0% organic carbon) as a substrate. The distribution of PCP in the microcosm media and organisms varied significantly as environmental conditions changed. There was significantly more PCP (or phenate ion) in the water at pH 8 than pH 6 or 4 in both the organic and inorganic systems. However, accumulation of PCP in most of the microcosm organisms was significantly greater at pH 4, followed by 6 and then 8. Partitioning of PCP into organic sediment followed the same trend with the highest amounts of PCP appearing in sediment at pH 4. The organic carbon content of sediment was important in determining partitioning into sediment; the 3% organic carbon sediment sorbed significantly more PCP than the 0% organic carbon sediment. In addition, the organisms in the 3% organic carbon sediment microcosms accumulated significantly less PCP then did those in the 0% organic carbon systems. The 3% organic carbon sediment also appeared to facilitate the breakdown of PCP in sediment and water. Among others these data indicate that hazard assessments should not be based on aqueous levels of PCP unless pH is considered.

Fate of pentachlorophenol (PCP) in sterile soils inoculated with the white-rot basidiomycete Phanerochaete chrysosporium: Mineralization, volatilization and depletion of PCP

The fate of pentachlorophenol (PCP) in three sterile soils inoculated with a white-rot basidiomycete, Phanerocaete chrysosporium, was investigated. Mineralization and volatilization of PCP and its transformation products and residual PCP concentration were measured for 2-months from soil microcosms inoculated with P. chrysosporium or left non-inoculated. There was a dramatic decrease (ave. decrease 98%) in the cxtractable PCP concentration in inoculated soils compared to that in non-inoculated soils (ave. decrease 43%). In the three inoculated soils, the greatest loss of PCP was during the first week. Initial rates of PCP depletion varied by soil. Differences among these soils in quantities of soil nutrients available for fungal growth, particularly carbon and nitrogen, may have been indirectly responsible for the differences by influencing the rates of soil colonization. Pentachlorophenol mineralized or evolved as volatile products was slight in the three soils. Our results suggest that P. chrysosporium removes PCP per se from soils primarily by converting it to non-volatile products. The nature of the products, whether they arc cxtractable or soil-bound, is greatly influenced by soil type.

Fate and effects of pentachlorophenol in hard- and soft-water microcosms

The influence of hard water and soft water on the fate and effects of pentachlorophenol (PCP) was investigated in small microcosms. Minor differences in the fate of PCP and minor changes in microcosm structure were noted between the hard- and soft-water systems. Definite differences between hard-and soft-water systems were detected in dissolved oxygen production and dissolved silica concentration at an exposure concentration of 4 mg 1−1 PCP.

Pentachlorophenol biodegradation—II: Anaerobic

The fate of pentachlorophenol (PCP) during anaerobic digestion of sewage sludge solids was tested in a three phase protocol. Phase I involved acclimation; Phase II investigated biodegradation in semicontinuous-flow, stirred-tank reactors at solids retention times of 10, 20 and 40 days; phase III assessed the importance of nonbiological removal mechanisms and collected additional data concerning the extent of biodegradation. PCP was found to inhibit methanogenesis in unacclimated cultures at concentrations in excess of 200 μg l −1 and thus acclimation of the digesters to PCP required very gradual increases in the influent concentration thereby allowing enrichment of organisms capable of degrading PCP. Once acclimation was achieved, digesters receiving influent containing 5.0 mg l −1 PCP achieved stable operation with effluent PCP concentrations below 5 μg l −1 at all retention times studied. Sorption was shown to be unimportant in PCP removal. Volatilization was considered to be unimportant based upon results obtained in forced aeration studies. This suggested that PCP was subject to at least primary biodegradation. Other evidence collected during the study indicated that more complete biodegradation probably was occurring.

The Fate of Pentachlorophenol in the Bay of Quinte, Lake Ontario

Unfiltered water, surface film, sediment, and biota samples were collected from the Bay of Quinte between May and September 1978 and analyzed for chlorophenols (CPs). Sectioned sediment cores were dated using 210Pb and 137Cs analyses. Pentachlorophenol (PCP) was found at high concentrations adjacent to a point source and was detected in all compartments examined throughout the bay (a bioaccumulation factor of 10 4 was observed for PCP in fish). The ratio of 2,3,4,6- and 2,3,5,6-tetrachlorophenols (TTCPs) to PCP increased with distance from the source in the water column and surface film. Photochemical reduction was proposed to account for the phenomenon. CP concentrations in sectioned cores suggested that settling particles adsorb CPs in similar proportion to that observed in the water column and little further change occurs after burial.

Fate of pentachlorophenol in cotton

Fate of pentachlorophenol in cotton