Bioflocculation coupled with inorganic salts in suspended solid removal in water

摘要

Generally FeCl3 and A1C3 can be used as inorganic flocculant.In order to remove the suspended solid in water(mainly kaoline particles,SS as high as 5g/L),the adding amount of FeCl3 or AlCl3 should be 100mg/L or higher,and if only bioflocculant is used alone.The needed amount of crude bioflocculant should be 3-5mL.This paper showed the study results on SS removing ability by the bioflocculant coupling with FeCl3 or AlCl3.The results showed that the bioflocculant effects can be reinforced by FeCl3 or AlCl3.When 72mg/L Ca2+ and 2mL crude bioflocculant produced by bacteria NII4 were added into 100mL water sample(SS=5g/L),the removing rate of SS is 92％.While 72mg/L Ca2+.0.5mL 5mg/L FeCl3 solution and 0.5mL the same crude bioflocculant as above were added into l00mL water sample(SS=5g/L),in 15min the water sample turn transparent,and the removing rate of SS is 95％.And the free Fe3+ left in supematant is 0.02～0.04mg/L,Ca2+ is about 67mg/L.Using 4mg/L AlCl3 instead of FeCl3,the needed amount of the same bioflocculant is 1.0mL,the removing rate of SS is almost the same.And the free Al3+ left in supernatant is 0.10-0.16mg/L.Ca2+ is about 65mg/L.Here the adding amount of FeCl3 or AICl3 is sO small(not more than 0.8mg/L)that it almost dose not increase the water treatment fee,but it can reduce the adding amount of bioflocculant about 3/4.And can low the water and wastewater treatment cost directly.Our biofloculant can enwrap and adsorb the kaoline particles to forill smaller enwrapped parcels which could act each other to form larger parcels.And finally to form the irregularin shaped flocs.