The Preparation Of High-efficiency Green Bioflocculant Under Microwave Conditions And Its Application In Various Wastewater Treatment

Bioflocculants is a kind of safe, toxic-free, diverse and biodegradable green waterpurifying agent. However, its industrial development was greatly constrained by the highpreparation cost and lack of serialization, critical bottlenecks to get this product intomarket. Given this problem, the microwave synthesis of high efficiency greenbioflocculants (GBF) and the application of GBF in wastewate r treatment were studied inthis paper based on the utilization of low-cost biological resource and the use of lowenergy consumption technology. Main conclusions of this paper are as follows:Preliminary preparatory of the microwave synthesis of green bioflocculants: Firstly,by the comparison of raw materials, wood flour was chosen as bioflocculant synthesis ofraw materials. Secondly, by comparing the hydrothermal heating with microwave heatingmethods, it was found that microwave heating can shorten reaction time by2h; in additionthat the limit viscosity was increased by about30%, and synthesizing bioflocculant underthe microwave heating conditions was ultimately determined. Finally, preparation processtechnology of cationic green bioflocculant (CGBF), anionic green bioflocculant (AGBF)and amphoteric green bioflocculant (AMGBF) was determined.The microwave synthesis of bioflocculants：Choosing limit viscosity as a referenceindicator, single-factor experimental method was applied to investigate the effects ofdispersants, catalysts, catalysis time, etherification agents, power and time of microwaveon the performances of the prepared bio-flocculants. Meanwhile the GBF preparationconditions were optimized through orthogonal experiment, when primary and secondaryinfluence order of various factors on the pruducts’ performance were analyzed. In the end,three kinds of GBF, that is CGBF, AGBF and AMGBF, were prepared in the optimizedconditions, whose limit viscosity is respectively0.6803dL/g,0.4121dL/g and0.7229dL/g.The structures of the prepared GBF were verified by infrared absorption spectroscopyanalysis. Application of GBF in wastewater treatment： In this part, inorganic flocculants wasused compounding with CGBF, AGBF and AMGBF respectively in the treatment ofcoal-washing wastewater, kaolin wastewater, food industry wastewater as well as dyeingwastewater. The results showed that pH application scope of different compound agentsvaried, while the three composite reagents showed good settling effect for the coal-washingwastewater. The removal efficiency of SS to food industry wastewater and that of color todyeing wastewater are significant and reached more than90%; the removal efficiency ofammonia, sulfate, and COD in simulated ammonia wastewater, sulfate wastewater, andfood industry waste water was about40%. Remarkably, during the treatment processcomposite reagents can play the role of improving the quality of wastewater. Finally,Flocculation and Precipitation-Anaerobic-Aerobic combination process was used in thetreatment of hard-degradation dyeing wastewater, the COD removal efficiency of whichraised by10%compared with simply biological treatment; Water quality was greatlyimproved, and stably reached the discharge standard of water pollutants for dyeing andfinishing of textile industry (GB4287-92); And this method can play an important role inreducing the toxicity in sludge.