Youssef Touhami

Ecological clarification of cheese whey prior to anaerobic digestion in upflow anaerobic filter.

Anaerobic digestion of cheese whey wastewaters (CW) was investigated in a system consisting of an ecological pretreatment followed by upflow anaerobic filter (UAF). The pretreatment was conducted to solve the inhibition problems during anaerobic treatment of CW caused by the amounts of fats, proteins and carbohydrates and to avoid the major problems of clogging in the reactor. The optimized ecological pretreatment of diluted CW induce removal yields of 50% of chemical oxygen demand (COD) and 60% of total suspended solids (TSS) after acidification by Lactobacillus paracasei at 32 degrees C during 20 h and neutralization with lime. The pretreated CW was used to feed UAF (35 degrees C). The effects of organic loading rate (OLR) and hydraulic retention time (HRT) on the pretreated CW anaerobic degradation were examined. The average total COD removals achieved was 80-90%. The performance of the reactor was depressed by increasing the COD concentration to 20 g/l (OLR = 4 gCOD/ld) and the COD removal efficiency was reduced to 72%. Significant methane yield (280 l/kg COD removal) was obtained at an HRT of 2 days.

Effect of nitrogen and carbon sources on Indigo and Congo red decolourization by Aspergillus alliaceus strain 121C.

The decolourizing ability of Aspergillus alliaceus 121C was investigated on solid medium. The effects of nitrogen (N), carbon (C) sources and supplements on the decolourization of Indigo and Congo red dyes were studied. It has been shown that both the nature and the quantity of available N- and C-sources exert an influence on growth and decolourization. For the six N-sources (NH(4)Cl, Diammonium Tartrate, urea, malt extract, peptone and yeast extract) tested for Congo red decolourization, 8mM yeast extract provided the higher decolourized zone diameter (80 mm) and colony diameter (80 mm). 12 mM urea provided the higher decolourized zone diameter (76+/-2mm) and colony diameter (80 mm) for Indigo decolourization. For the C-sources tested (glucose, starch, glycerol and lactose), above 12.5mM of glucose and 62.5mM of starch provided the higher decolourized zones diameters of 80 mm and 77+/-3mm for Indigo and Congo red, respectively. When the fungi was grown in liquid medium containing optimum carbon and nitrogen sources supplemented with oak sawdust and wheat bran, more than 98.6% and 98% of colour removal are obtained for Indigo and Congo red dyes, respectively. The detection of ligninolytic enzymes proved that laccase and lignine-peroxidase (LiP) are the two enzymes responsible of the decolourization of the two dyes.

Bacterial monitoring by molecular tools of a continuous stirred tank reactor treating textile wastewater.

This study was performed to examine the effect of the bacterial diversity changes on the performances of a continuously stirred tank reactor (CSTR) treating textile wastewater. The molecular fingerprint established using polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) methods showed that bacterial community profiles changed simultaneously with the increase of the wastewater loading rates (WLR). For the two WLR of 0.28 g l(-1)d(-1) and 0.37 g l(-1)d(-1), the reactor maintained good performances, suggesting that the large bacterial community present a high specific activity. The increase of the WLR from 0.37 to 1.12 g l(-1)d(-1) decreased the colour and the chemical oxygen demand (COD) removal efficiencies from 90% to 55% and from 85% to 30%, respectively, explained by the decrease of the bacterial diversity and activity. The changes of the bacterial dominance had no affect on the reactor performances. However, the decrease of the bacterial diversity significantly affected the colour and the COD removal efficiencies. It should conclude that indigo dye-containing textile wastewater treatment required the concerted activity of multiple bacterial populations.

Exploring bioaugmentation strategies for the decolourization of textile wastewater using a two species consortium (Bacillus cereus and Bacillus pumilus) and characterization of produced metabolites

Abstract Two bacterial strains, Bacillus cereus and Bacillus pumilus, were isolated from the sludge of an aerobic reactor treating textile wastewater containing indigo dye. These strains were chosen as augmented decolourizers which were mixed in various ratios with the activated sludge and the effect of their concerted metabolism on the decolourization and the biodegradation efficiencies were studied. Results showed that there was an equilibrated ratio between the bioaugmented bacteria and the other microorganisms of the activated sludge. However, the best yields were observed for the combination 33% activated sludge, 33% Bacillus cereus and 33% Bacillus pumilus, with a colour and carbon oxygen demand (COD) removal of 98% and 99% respectively, obtained after 48 h of incubation. The high performance liquid chromatography (HPLC), Proton Nuclear Magnetic Resonance (1H NMR) analysis of the produced metabolites after the biodegradation of the dye by the bioaugmented consortium showed the presence of protons on...