ZHOU Lu, PENG Biao
Journal of Tsinghua University(Science and Technology). 2015, 55(6): 653-659.
Wastewater from dyeing and printing factories is difficult to treat. Such wastewater is often treated using activated sludge process, but the removal efficiency is not good. Many micronutrients play important roles in the metabolic activity of microorganisms in the activated sludge; thus, the micronutrients can affect the treatment efficiency of dyeing printing wastewater. Experiments were conducted to evaluate the effects of single metal elements, such as Mo, Zn and Co, and combinations of these metal elements on the treatment efficiency of dyeing printing wastewater and the SOUR of activated sludge using a sequencing batch reactor. The results show that dyeing printing wastewater lacks the Mo, Zn, Fe, Al and Co which are important for the metabolic activity of the microorganisms in the activated sludge. The biological treatment of dyeing printing wastewater can be very different depending on the species, concentration and form of the metal elements. When adding single metal elements into the reactor, the optimum concentrations of Mo, Zn, Fe, Al and Co were 0.3 mg/L, 0.3 mg/L, 0.4 mg/L, 0.5 mg/L and 4 mg/L. The removal rate of CODCr, relative to the rate without any micronutrients is increased 5.82% by Mo, 12.85% by Zn, 5.26% by Fe, 8.28% by Al and 9.66% by Co and the SOUR of the microbial activity in the activated sludge is increased 68.51% by Mo, 74.87% by Zn, 6.15% by Fe, 21.70% by Al and 71.64% by Co. The microorganism metabolic activity was increased by adding Mo, Zn and Co which improved the treatment efficiency. The improved treatment efficiency with Al and Fe was mainly due to the enhanced coagulation with these elements. The interactions of different micronutrients is difficult to predict in microbial communities. The anions of the metal salts had no effect on the biological effects of the trace metals.
