The Experimental Study On The Treatment To Mine Wastewater Contained High Concentration Of Manganese With Nano-composite

Mine waste water contained high concentration of manganese which is the main source of its pollution on water, has gradually bring serious hazard to water resources and human health with the increasing sewage disposal. The porous composite material which was compounded by nano-molecular sieve, diatomite and kaolin reasonably, and then added by the complex mixing of flocculants was studied in the manganese removal test in mine wastewater. The static and dynamic tests was used in the experiments.The manganese removal capability and conditions for activation of nano-molecular sieve, diatomite and kaolin, as well as the appropriate way to compound was tested in static experiments. The porous composite material was prepared after mixing compound flocculants. Different effect factors on manganese removal were investigated, such as adsorption time, dosage and the pH, Mn²⁺ concentration of the wastewater, and the effect of Fe³⁺ and SS were also investigated. Then the composite were compared with the nano-molecular sieve in the actual waste water treatment. The results show that: (1) the manganese removal was up to 62.6% by using nano-molecular sieve, but the effluent water was with a high pH after treatment, while the largest manganese removal can only be 50.0% by using diatomite or kaolin; (2) the best conditions for activation of nano-molecular sieve is calcined in 400℃for 1.5 h, and for diatomite is calcined in 600℃for 2 h; (3) the tests'results of the influence of the method for preparing composite material on manganese removal indicated that composite materials prepared by high-energy ball milling method has higher manganese removal performance and lower nano-molecular sieve usage than by grinding method. The proper method is that the proportion of nano-molecular sieve to CD10 is 3 to 1, milling 30 min and then calcining in 600℃for 3 h; (4) the proportion of PAC to PAM is 1 to 1, adding 3 mg/L; (5) when the influent density of Mn²⁺ was 20 mg/L, the optimized adsorption time is 10 min, the composite materials dose is 0.6 g/L, pH is about 8; the removal rate reduced while the adsorption capacity improved as Mn2+ concentration increased; the existence of Fe³⁺ in wastewater is unfavorable to manganese removal while the existence of SS has no significant impact; the effluent turbidity is lower and much more economical by the treatment to actual mine wastewater with nano-composite than with the nano-molecular sieve.Different effect factors on manganese removal were investigated in dynamic experiments, such as sediment time, height of sediment column, dosage and the inflow to determine the best technological parameters and compare the differents of composite and nano-molecular sieve in manganese removal. The results showed that: (1) when the inflow was 100 L, nano-composite dose was 45 g, while when the inflow was 200 L, and nano-composite dose was 80 g. After stirring for 10 min, pumping the water into column for sedimentation, the effluent reached the discharge standard. The turbidity was the smallest where the height of sediment column was 100 cm after standing for 45 min; (2) the ratio of nano-composite dose to water volume is not a fixed value, but decreased with the increase of water volume; (3) compared with the use of nano-molecular sieve, the weight of nano-molecular sieve used is decreased after compounding. Besides, turbidity in effluent was reduced. The nano-composite was characterized by XRD and IR. Through XRD analysisthe structure of nano-composite mainly were SiO₂, Na(x)Al(y Si(z)·nH₂O, amorphous SiO₂ and quartz; Through IR analysis, the bonds of nano-molecular sieve and diatomite occurred chemical reaction in the time of compounding and there were some new structures generated.