Pilot-scale Synthesis And Application Evaluation Of The Cellulose-based Green Flocculating Material

Flocculation is the most widely used wastewater treatment method,but also the most effective and economical method of wastewater treatment.Flocculation has a great effect in the treatment of the wastewaters with heavy metal ions,suspended colloidal particles or dyes.The chemical agent used in flocculation is called flocculant.Currently,it is generally divided into four categories as inorganic,synthetic organic polymer,modified natural polymer and microbial flocculants.The synthetic organic polymer flocculant has the advantages of excellent flocculation effect and low dosage,but holds the disadvantage of secondary pollution.The modified natural polymer flocculant also has excellent flocculation performance.It inherites the advantages of natural polymer compounds such as no biological toxicity and biodegradation due to its natural polymer compound segment,and reduces the secondary pollution of synthetic organic polymer flocculant.Therefore,the modified natural polymer flocculant has been one of the hotspots in the field of flocculants synthesis.In this work,the pilot-scale cellulose-based green flocculating material product was prepared by grafting polyacrylamide onto the bamboo pulp cellulose.A series of characterization of the cellulose-based green flocculating material was carried out.Its flocculation performance to kaolin suspension and actual industrial wastewater was evaluated.The cellulose-based green flocculating material products were applied in the treatment processes of different types of actual industrial wastewater.The flocculation performance of the product,the overall cost of the treatment and the application prospects of the cellulose-based green flocculating material were also evaluated.The preparation and research of a novel cellulose-based green flocculating material which is environment-friendly and biodegradable were completed.The specific research contents and conclusions are as follows:1.Pilot-scale synthesis and flocculation performance evaluation of the cellulose-based flocculantIn pilot scale,the bamboo pulp was used as raw material.A novel green cellulose-based flocculating material was prepared by grafting polyacrylamide onto the backbone of bamboo pulp cellulose through free radical initiation.Through the fine-tuning of experimental process,the optimal preparation process(1 ton)was obtained as: reaction temperature at 50℃,initiator at 10 kg,bamboo pulp at 40 kg,polyacrylamide at 40 kg,the reaction time at 1 h.The turbidity removal rate of kaolin suspension reached 98.9%.The turbidity removal rate of papermaking wastewater reached 99.9%,and CODCr removal rate reached 73.5%.The above results showed that the product prepared by pilot scale had excellent flocculation performance.2.Evaluation of pilot-scale application of cellulose-based green flocculating meterialOptimum flocculation process by flocculation experiment of dyeing wastewater and mechanical processing wastewater was applied to the actual wastewater treatment process.The turbidity removal rate of dyeing wastewater reached 94.62%,CODCr removal rate reached 93.21%,and BOD5 removal rate reached 93.21%.The turbidity removal rate of mechanical processing wastewater reached 97.7%,CODCr removal rate reached 57.1%,and BOD5 removal rate reached 38.5%.In view of these results,the obtained cellulose-based green flocculating meterial has a great market prospects.