Bozidar Santek

Removal of Cr, Mn, and Co from textile wastewater by horizontal rotating tubular bioreactor.

Environmental pollution by industrial wastewaters polluted with toxic heavy metals is of great concern. Various guidelines regulate the quality of water released from industrial plants and of surface waters. In wastewater treatment, bioreactors with microbial biofilms are widely used. A horizontal rotating tubular bioreactor (HRTB) is a combination of a thin layer and a biodisc reactor with an interior divided by O-ring shaped partition walls as carriers for microbial biomass. Using a biofilm of heavy metal resistant bacteria in combination with this special design provides various advantages for wastewater treatment proven in a pilot study. In the presented study, the applicability of HRTB for removing metals commonly present in textile wastewaters (chromium, manganese, cobalt) was investigated. Artificial wastewaters with a load of 125 mg/L of each metal underwent the bioreactor treatment. Different process parameters (inflow rate, rotation speed) were applied for optimizing the removal efficiency. Samples were drawn along the bioreactor length for monitoring the metal contents on site by UV-vis spectrometry. The metal uptake of the biomass was determined by ICP-MS after acidic microwave assisted digestion. The maximum removal rates obtained for chromium, manganese, and cobalt were: 100%, 94%, and 69%, respectively.

Production of paramylon, a β‐1,3‐glucan, by heterotrophic cultivation of Euglena gracilis on potato liquor

Euglena gracilis is shown to be able to grow on potato liquor as the main medium component leading to an interesting biotechnological product represented by paramylon – a β‐1,3‐glucan – and, at the same time, revaluating an otherwise annoying waste stream of the potato‐starch industry. Paramylon mass fractions of about 75% are obtained for biomass concentrations of 15 g/L during simple batch cultivation under heterotrophic conditions. Supplementation of the growth medium with glucose and the vitamins B1 and B12 are shown to improve growth rate as well as paramylon content. E. gracilis grows best at about 27.5°C without requiring pH control.