Characterization of lighted upflow anaerobic sludge blanket (LUASB) methodunder sulfate-rich conditions

Growth of phototrophic bacteria was induced from granules in a lighted upfl ow anaerobic sludge blanket (LUASB) reactor supplied with an organic-acid-b ased medium containing 141.7 mg S l(-1) of SO42- under light conditions (10 0 muE .m(-2).s(-l)). We investigated the population dynamics of phototrophi c bacteria in the LUASB reactor and the performance of the LUASB reactor fo r wastewater treatment and poly-beta -hydroxybutyrate (PHB) production unde r anaerobic light and sulfate-rich conditions. In vivo absorption spectra a nd a colony count suggested that populations of Rhodopseudomonas palustris and Blastochloris sulfoviridis in the LUASB reactor supplied with a medium containing 574.4 mg S .l(-1) of SO42- under light conditions were lower tha n those supplied with a medium containing 1.0 or 141.7 mg S .l(-1) of SO42- under parallel conditions. Removal efficiencies of ammonium and phosphate in the LUASB reactor supplied with the medium containing 141.7 mg S .l(-1) of SO42- under light conditions were higher than those under parallel condi tions but without illumination. The difference in the results of runs under light or dark conditions suggested that the ammonium and phosphate ion rem oval efficiencies were improved by increasing the amount of phototrophic ba cterial biomass in the LUASB reactor under sulfate-rich conditions. The ave rage PHB production rates of the bacterial cells recovered from the effluen t of the LUASB reactor supplied with a medium containing 141.7, 283.5 or 57 4.4 mg S .l(-1) of SO42- were 1.0-2.9 mg .l(-1)-reactor d(-1) and the avera ge PHB content based on the dry bacterial biomass was 1.4-3.6%.