Textile wastewater bioremediation using immobilized Chlorella sp. Wu-G23 with continuous culture

Abstract

Immobilized microalga Chlorella sp. Wu-G23 (G23) was entrapped inside a polymer matrix or appended on the surface of a strong solid carrier. Alginates then formed a microalgae/polymeric matrix granule within the cross-linking solution. The textile wastewater bioremediation technology using immobilized G23 in textile wastewater effectively removed chemical oxygen demand (COD), ammonium nitrogen (NH4+-N) and color after 7 days of cultivation. Batch model results show that the optimal cultivation parameters for simultaneously removing textile wastewater pollutants and accumulating lipids were initial pH 10 with extra urea 1 g/L and K2HPO4 8 mg/L added without aeration. A bioreactor cultivated the immobilized G23 at hydraulic retention time of 48 h with continuously fed textile wastewater for 440 h. Peak removal efficiencies of NH4+-N 80.2%, COD 70.8% and color 77.9% with fatty acid methyl esters 10% were achieved. The color removal occurred through the biosorption mechanism using nonviable suspended and immobilized microalgae biomass. The NH4+-N and COD could be degraded in the cell-free, nonviable microalgae because the microorganism in the textile wastewater could utilize them as a nutrient source.