Treatment of wine distillery wastewater by high rate anaerobic digestion.

Wine distillery wastewaters (WDW) are acidic and have a high content of potential organic pollutants. This causes high chemical oxygen demand (COD) values. Polyphenols constitute a significant portion of this COD, and limit the efficiency of biological treatment of WDWs. WDW starting parameters were as follows: pH 3.83, 4,185 mg/l soluble COD (COD(s)) and 674.6 mg/l of phenols. During operation, amendments of CaCO3 and K2HPO4, individually or in combination, were required for buffering the digester. Volatile fatty acid concentrations were < 300 mg/l throughout the study, indicating degradation of organic acids present. Mean COD(s) removal efficiency for the 130 day study was 87%, while the mean polyphenol, removal efficiency was 63%. Addition of 50 mg/l Fe(3+) between days 86 and 92 increased the removal efficiencies of COD(s) to 97% and of polyphenols to 65%. Addition of Co(3+) improved removal efficiencies to 97% for COD(s) and 92% for polyphenols. Optimization of anaerobic treatment was achieved at 30% WDW feed strength. Removal efficiencies of 92% and 84% were recorded at increased feed strength from days 108 to 130. High removal efficiencies of COD(s) and polyphenols after day 82 were attributed to the addition of macronutrients and micronutrients that caused pH stability and thus stimulated microbial activity.

The enzymology of sludge solubilisation utilising sulphate reducing systems: the role of lipases.

The first stage in the degradation and recycling of particulate organic matter is the solubilisation and enhanced hydrolysis of complex polymeric organic carbon structures associated with the sulphidogenic environment. An investigation into the enzymology of these processes has shown that lipase enzyme activities were found predominantly associated with the organic particulate matter of the sewage sludge. Sonication of the sludge gave an increase in enzyme activity as the enzymes were released into the supernatant. pH and temperature optimisation studies showed optima at between 6.5 and 8 and 50-60 degrees C, respectively. All the lipase enzymes from the methanogenic bioreactors indicated extensive stability for at least an hour at their respective optimum temperatures and pH; sulphidogenic lipases reflected limited stability at these temperatures and pH during this time period. Though sulphate showed inhibitory properties towards lipases both sulphide and sulphite appeared to enhance the activity of the enzymes. It is argued that these sulphur species, liberated at different times during the sulphate reduction process, disrupt the integrity of the organic particulate floc by neutralising acidic components on the surface. The release of further entrapped enzymes from the organic particulate matter results in a subsequent enhancement of hydrolysis of polymeric material.

The enzymology of sludge solubilisation utilising sulphate-reducing systems: the properties of lipases.

The first stage in the degradation and recycling of particulate organic matter is the solubilisation and enhanced hydrolysis of complex polymeric organic carbon structures associated with the sulphidogenic environment. An investigation into the enzymology of these processes has shown that lipase enzyme activities were found predominantly associated with the organic particulate matter of the sewage sludge. Sonication of the sludge gave an increase in enzyme activity as the enzymes were released into the supernatant. pH and temperature optimisation studies showed optima between 6.5 and 8 and 50-60 degrees C, respectively. All the lipase enzymes from the methanogenic bioreactors indicated extensive stability for at least an hour at their respective optimum temperatures and pH; sulphidogenic lipases reflected limited stability at these temperatures and pH during this time period. Though sulphate showed inhibitory properties towards lipases both sulphide and sulphite appeared to enhance the activity of the enzymes. It is argued that these sulphur species, liberated at different times during the sulphate reduction process, disrupt the integrity of the organic particulate floc by neutralising acidic components on the surface. The release of further entrapped enzymes from the organic particulate matter result in a subsequent enhancement of hydrolysis of polymeric material.