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This review focuses on hazardous waste treatment technologies published in 2001 and consists of two main parts: (1) biological treatment and (2) physical and chemical treatment. BIOLOGICAL TREATMENT Aerobic Processes. Substrate interactions in benzene, toluene, ethyl benzene, and xylene (BTEX) and methyl tert-butyl ether (MTBE) mixtures by an MTBE-degrading isolate, PM1 were studied (Deeb et al., 2001). BTEX and MTBE degradation occurred primarily via two independent and inducible pathways. Severe inhibition of MTBE degradation by ethylbenzene and the xylenes and the partial inhibition by benzene and toluene were observed. Hatzinger et al. (2001) evaluated biodegradation of MTBE by the hydrogen-oxidizing bacterium Hydrogenophaga flava ENV735. Growth of ENV735 on MTBE or tert-butyl alcohol (TBA) as sole sources of carbon and energy was greatly enhanced by the addition of a small amount of yeast extract while the supplement of hydrogen gas (H 2 ) did not affect MTBE degradation by the strain. MTBE degradation activity was constitutively expressed in ENV735 and was not greatly affected by formaldehyde, carbon monoxide, allyl thiourea, or acetylene but was inhibited by 1amino benzotriazole and butadiene monoepoxide. Kane et al. (2001) studied the potential for aerobic MTBE degradation with microcosms containing aquifer sediment and groundwater from four MTBE-contaminated sites characterized by oxygen-limited in situ conditions. The effects of oxygen and water-soluble gasoline components on in situ MTBE degradation varied from site to site and phylogenetic analysis might be a promising predictor of MTBE biodegradation potential. Liu et al. (2001a) reported that Arthrobacter bacteria demonstrated MTBE degradation activity when grown on butane but not when grown on glucose, butanol, or tryptose phosphate broth. The presence of butane, tert-butyl alcohol, or acetylene had an adverse impact on the MTBE degradation rate. Neither Methylosinus trichosporium OB3b nor Streptomyces griseus was able to cometabolize MTBE. Pruden et al. (2001) developed five aerobic Literature Review 2002 3 examined (Fava and Di Gioia, 2001). A substantial decrease of soil ecotoxicity was observed in SL-supplemented microcosms and SL was found to be a good carbon source for both indigenous and ECO3 bacteria, as well as a product capable of enhancing the PCB bioavailability in the microcosms. Kim and Picardal (2001) isolated bacterial strains, SK-3 and SK-4, capable of aerobic growth on ortho-substituted dichlorobiphenyls as sole carbon and energy sources. During growth on 2,2'dichlorobiphenyl and 2,4'-dichlorobiphenyl strain SK-4 produced stoichiometric amounts of 2-chlorobenzoate and 4-chlorobenzoate which were not formed when strain SK-3 was grown on 2,4'-dichlorobiphenyl. Zhoa and Ward (2001) studied substrate selectivity of a 3-nitrophenol-induced metabolic system in Pseudomonas putida 2NP8 transforming nitroaromatic compounds into ammonia under aerobic conditions. All of the 30 monoor dinitroaromatic substrates except 4-nitrophenol, 2,4-dinit...

This review focuses on hazardous waste treatment technologies published in 2004 and consists of two main parts: (1) biological treatment and (2) physical and chemical treatment. BIOLOGICAL TREATMENT Aerobic Processes. Johnson et al. (2004) investigated the effects of methyl tertiary butyl ether (MTBE) on the MTBE oxidizing activity of Mycobacterium vaccae JOB5. MTBE enhanced MTBE oxidation in cells grown on organic acids, compounds that are commonly found in anaerobic, gasoline-contaminated environments. Maliyekkal et al. (2004) evaluated the performance of benzene, toluene, and xylene degradersunder substrate versatility conditions. The degree of degradation was in the following order: toluene > benzene > xylene. Nicholson and Fathepure (2004) examined the biodegradation of benzene by halophilic and halotolerant bacteria under aerobic conditions. The enrichment, which was dominated by Marinobacter spp., was able to mineralize benzene. Pruden and Suidan (2004) evaluated the effect of benzene, toluene, ethylbenzene, and xylene (BTEX) mixture on biodegradation MTBE and tertbutyl alcohol (TBA) by pure culture UC1. The BTEX mixture did not affect either the rate 2145 or the lag period of MTBE or TBA degradation, except that increases in the TBA degradation rate in the presence of BTEX were occasionally observed. Shi et al. (2004a) examined the biodegradation of natural and synthetic estrogens by nitrifying activated sludge and ammonia-oxidizing bacterium Nitrosomonas europaea. Significant degradation of estrone (E1), 17beta-estradiol (E2), estriol (E3), and ethynylestradiol (EE2) by both cultures was observed. Microbial degradation of estrogens using activated sludge and night soil-composting microorganisms was studied (Shi et al., 2004b). Both cultures almost completely degraded natural estrogens E1, E2, and E3 from initial concentrations of 20-25 mg L -1 , while synthetic estrogen, EE2, was not degraded. Yoshimoto et al. (2004) studied the degradation of estrogens by Rhodococcus zopfii and Rhodococcus equi isolates from activated sludge in wastewater treatment plants. Both isolates completely and rapidly degraded 100 mg of E1, E2, E3, and EE2 L -1 . Chang et al. (2004a) isolated two aerobic phthalic acid ester (PAE) degrading bacteria strains, DK4 and O18 from river sediment and petrochemical sludge, respectively. The two strains rapidly degraded PAE with shorter alkyl-chains while PAE with longer alkyl-chains was poorly degraded. Itrich and Federle (2004) conducted batch activated-sludge die-away studies to determine the effect of ethoxylate number and alkyl chain length on the kinetics of biodegradation of linear alcohol ethoxylates. Ethoxylate number had little effect on the first-order rates for primary biodegradation while alkyl chain length had a larger effect. Aerobic biodegradation of linear alkylbenzene sulfonates (LAS) and their degradation intermediates in seawater was examined (Leon et al., 2004).Fournier et al. (2004) studied the biodegradation of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) ...

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