Study On Preparation And Application Of A Novel Environmentally Friendly Composite Flocculant

The shortage of water resource and water environment pollution have been the important factors of restricting national economic and social development of our country. Flocculation is a kind of method and technique of purifying water in common use,but the conventional flocculants such as polyaluminium chloride (PAC) and polyacrylamide (PAM) in water treatment are prone to produce secondary pollution, the aluminum ions that is produced from hydrolysis of PAC in water come into human body via feed water and cause various diseases such as anaemia, hair-losing and brain dementia etc., crylic acid and amine that are produced from hydrolysis of PAM would harm human health too. So how to prepare a kind of novel environmentally friendly flocculant which is of less pollution and better flocculating performance is a very important subject and an urgent task in water treatment field recently.In this paper a new composite flocculant (attained based on CF-PAC, bAl-pillared montmorillonite and chitosan) applied to treat with tap water and another new composite flocculant (attained based on CF-PAC, PAM and chitosan) applied to treat with papermaking wastewater have tested and investigated carefully and deeply, Inorganic flocculant CF-PAC, Al-pillared montmorillonite act as sorption mostly; Meanwhile organic flocculant chitosan and PAM act as the adsorption bridge mainly. Chitosan coagulates fine flocci together into lager, impact floccules and greatly strengthens the polymerization degree and coacervation force. The sedimentation rate and adsorption efficiency rise greatly. So the flocculation efficiency of this composite flocculant is superior to the single one. The course of studying can be divided into two parts.The first part is about the preparation of Al-pillared montmorillonite. The effect of preparation method of Al-pillared montmorillonite agent, montmorillonite suspending concentration, Al-pillared agent dosage, pillaring reacting temperature, pillaring reacting time are investigated, and the best craft condition has been ascertained. Then the capability has compared with the nature montmorillonite.and Al-pillared montmorillonite. The result shows: Compared with the nature montmorillonite and Al-pillared montmorillonite, the efficiency of eliminating CODcr is 11.5% and 1.8%, respectively, the efficiency of eliminating SS is 26% and 1.5 %, and the cost is reduced by 6.5 % and 3 % respectively.The second part focuses on the treatment research of the tap water using CF-PAC, Al-pillared montmorillonite / chitosan composite flocculant and the papermaking wastewater using CF-PAC, PAM/ chitosan composite flocculant. The optimal dosage and adding order for the tap water and the papermaking wastewater using the new composite flocculants are determined. The effect of pH value, reacting temperature, stirring speed and time, resting time are studied. The optimal dosages and flow are obtained too. The result shows that the new composite flocculant appears excellent flocculantion efficiency. Compared with the gathers the aluminum class flocculant of Wuhan Yu Jiatou tap water factory, the cloudiness and concentration of aluminum ion of exit water were respectively descended by 4.3% and 26%, the ton sewage medicament cost dropped 25 % .Achieving the aluminum ion content standard of our country tap water, making the tap water more safe.When compared with the composite flocculant using PAM/PAC of Wuhan ChenMIng paper industry, the efficiency of eliminating CODcr and SS respectively are enhanced by 27.7%and 10.8% The ton sewage medicament cost dropped 31.9%.So this novel flocculant is of obviously economical and the environmental benefits.