TY - JOUR
T1 - Coupled photocatalytic-biodegradation of 2,4,5-trichlorophenol
T2 - Effects of photolytic and photocatalytic effluent composition on bioreactor process performance, community diversity, and resistance and resilience to perturbation
AU - Marsolek, Michael D.
AU - Kirisits, Mary Jo
AU - Gray, Kimberly A.
AU - Rittmann, Bruce E.
N1 - Funding Information:
The authors acknowledge Mwende Munyasya for her work identifying the ideal photocatalytic reactor conditions, and John Kelly for guidance with DGGE and equipment support. The work was supported by the EMSI program of the National Science Foundation and the Department of Energy, through the Northwestern Institute of Environmental Catalysis ( CHE-9810378 ).
PY - 2014/3/1
Y1 - 2014/3/1
N2 - Sequentially coupled advanced oxidation-biodegradation systems have proven effective for treating a variety of wastewaters, but in several cases the pretreatment did not improve, or even hindered, subsequent biodegradation. Therefore, investigating the relationship between advanced oxidation pretreated effluent and subsequent bioreactor performance can help to optimize these systems. Here, a photocatalytic reactor was used to produce four unique effluents from 2,4,5-trichlorophenol (TCP) by varying light wavelength, catalyst presence, and reaction time, demonstrating that the conditions of photocatalytic pretreatment can be tuned to achieve a variety of treatment objectives. The photocatalytic effluents were characterized for chemical oxygen demand (COD), chloride release, aromaticity, and residual TCP concentration. The four effluents were normalized to 40mg COD/L, combined with biological medium components, and fed to continuous bioreactors. Bioreactors were assayed for COD removal, TCP removal, optical density (OD), and microbial diversity via denaturing gradient gel electrophoresis. In general COD removal in the bioreactors increased as aromatic character of the photoeffluent decreased, but the least aromatic effluent performed poorly indicating the nuanced relationship between photoreactor effluent composition and bioreactor performance. While neither indicator of community diversity, richness nor evenness, correlated with COD removal or biomass accumulation, each effluent produced a unique community as indicated through similarity indices. All conditions demonstrated strong overall TCP removal. After two weeks at steady state, the reactors were perturbed with a 120-μM spike of TCP. Overall the most aromatic photoeffluent produced the most resistant community to the perturbation, while the optimum effluents at steady state produced communities with poor resistance in terms of biomass accumulation and COD removal. These results highlight the tradeoffs between steady state performance and resistance to perturbation that are necessary to optimize a combined advanced oxidation-biodegradation treatment strategy.
AB - Sequentially coupled advanced oxidation-biodegradation systems have proven effective for treating a variety of wastewaters, but in several cases the pretreatment did not improve, or even hindered, subsequent biodegradation. Therefore, investigating the relationship between advanced oxidation pretreated effluent and subsequent bioreactor performance can help to optimize these systems. Here, a photocatalytic reactor was used to produce four unique effluents from 2,4,5-trichlorophenol (TCP) by varying light wavelength, catalyst presence, and reaction time, demonstrating that the conditions of photocatalytic pretreatment can be tuned to achieve a variety of treatment objectives. The photocatalytic effluents were characterized for chemical oxygen demand (COD), chloride release, aromaticity, and residual TCP concentration. The four effluents were normalized to 40mg COD/L, combined with biological medium components, and fed to continuous bioreactors. Bioreactors were assayed for COD removal, TCP removal, optical density (OD), and microbial diversity via denaturing gradient gel electrophoresis. In general COD removal in the bioreactors increased as aromatic character of the photoeffluent decreased, but the least aromatic effluent performed poorly indicating the nuanced relationship between photoreactor effluent composition and bioreactor performance. While neither indicator of community diversity, richness nor evenness, correlated with COD removal or biomass accumulation, each effluent produced a unique community as indicated through similarity indices. All conditions demonstrated strong overall TCP removal. After two weeks at steady state, the reactors were perturbed with a 120-μM spike of TCP. Overall the most aromatic photoeffluent produced the most resistant community to the perturbation, while the optimum effluents at steady state produced communities with poor resistance in terms of biomass accumulation and COD removal. These results highlight the tradeoffs between steady state performance and resistance to perturbation that are necessary to optimize a combined advanced oxidation-biodegradation treatment strategy.
KW - 2,4,5-Trichlorophenol
KW - Biodegradation
KW - Diversity
KW - Photocatalysis
KW - Resilience
KW - Resistance
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U2 - 10.1016/j.watres.2013.11.043
DO - 10.1016/j.watres.2013.11.043
M3 - Article
C2 - 24361703
AN - SCOPUS:84890839303
SN - 0043-1354
VL - 50
SP - 59
EP - 69
JO - Water Research
JF - Water Research
ER -