Removal of some azo dyes used in textile industry via microgel reactor

Dyes are used in large quantity within industries such as pharmaceutical, cosmetic food, textile, printing and leather industries. Especially textile industry is one of the most important sectors for liquid effluent pollutants. In this industry, textile dyes of 280000 tonnes are discharged as waste effluent every year worldwide. Discharge of effluents into aquarius environment such lakes and rivers results into reduced dissolved oxygen concentration, thus creating anoxic conditions that are detrimental to resident organisms. More importantly they cause problem because they contain carcinogenic and toxic features. Reducing the concentration of such dyes before discharging them into natural water streams is essential. Traditional technologies are not always effective or may not be environmentally friendly to treat recalcitrant and toxic dyes. Thus, the use of microorganism is one of a promising alternative replacement or complement the current technologies for colour removal. Especially processes using immobilised growing cells are looking promising than those with free cells due to the immobilisation enables using the microbial cells repeatedly and continuously. Objective of this study was to evaluate the decolourisation of reactive azo dyes (R. Red 3, A. Orange 74, R. Yellow 42, R. Black 5, R. Blue 4) that were used for colouring denim from an aqueous environment by microbial processes. For this purpose of a fungus Aspergillus niger was used for dye removal from synthetic and waste effluent via entrapping of microbial cells into polymer. Waste water quality tests such as Chemical Oxygen Demand (COD), Biological Oxygen demand (BOD) total solids (TS) Total Dissolved Solids, Total organic carbon (TOC) were done as well as decolourisation test of textile effluents which was obtained after denim dye processes. Also various concentration of sucrose and dye were tested. Over %90 of decolourization was achieved over of period 24hours's reaction time in batch tests. Especially, the ratio of COD, and colour of textile effluents were decreased as 75% and 99,8% respectively via immobilised culture of Aspergillus niger.