Study on contrast test of PPC pre-oxidation and coagulation for algae removal and deodorization

The effect of treating algae-bearing water and induced odor by use of permanganate potassium composite （PPC） pre-oxidation was investigated, and was compared with the effect of treatments by pre-chlorination, permanganate petassium pre-oxidation and simple coagulation. The results showed that simple coagulation and pre-chlorination were less effective in removing algae and its odor, whereas PPC pre-oxidation was the most effective in algae removal and deodorization. Upon oxidation with PPC, the cells of Oscillatoria agardhic were inactivated and some intra-cellular and extra-cellular components were released into the water, which may help the coagulation by their bridging effect. The efficient removal of algae by PPC pre-oxidation is believed to be the joint contribution of several mechanisms.

Alga-lysing bioreactor and dominant bacteria strain

Alga-lysing bacteria have been paid much attention to in recent years. In this study, the alga-lysing strain P05 which was isolated from an immobilizing biosystem was immobilized by coke and elastic filler, forming two biological reactors. The removal efficiencies of algae, NH4^＋-N and organic matter using the two reactors were studied. The results showed that strain P05 was an ideal algal-lysing bacteria strain because it was easy to be immobilized by coke and elastic filler which are of cheap, low biodegradability and the simple immobilization procedure. After 7 d filming, the biological film could be formed and the reactors were used to treat the eutrophic water. These two reactors were of stability and high effect with low cost and easy operation. The optimal hydraulic retention time （HRT） of each reactor was 4 h. The algae removal rates were 80.38% and 82.1% （in term of Chl-α） of coke reactor and filler reactor, respectively. And that of NH4^＋-N were 52.3% and 52.7%. The removal rates of CODMn were 39.03% and 39.64%. The strain P05 was identified as Bacillus sp. by PCR amplification of the 16S rRNA gene, BLAST analysis, and comparison with sequences in the GenBank nucleotide database.

Efficient removal of algae and turbidity from water by a composite coagulant composed of a cationic starch and attapulgite

Algae and suspended colloidal particles produced high turbidity in water,weakened water purification,and threatened the safety of the water supply.In this study,a series of composite coagulants(atp-st-CTA)composed of a cationic starch(st-CTA)and attapulgite(ATP)with different fed mass ratios were fabricated by a simple method to coagulate kaolin suspension with initial turbidity of 80.0 NTU and Chlorella suspension with 0.25 mg/L of chlorophyll a(chla),respectively.Fourier transform infrared spectroscopy and scanning electron microscopy investigated the structural characteristics of atp-st-CTA.The maximum turbidity and chla removal rates of atp-st-CTA were 92.2%and 100.0%,respectively,at natural pH conditions.The effects of the fed mass ratio of st-CTA to ATP in the composites,dose,pH,and coexisting humic acid on the coagulation performance of atp-st-CTA were comprehensively investigated.Based on the apparent coagulation behaviors,the zeta potentials of the supernatants after coagulation,and the flocs properties,the coagulation mechanisms of atp-st-CTA were discussed in detail.The complete charge neutralization due to st-CTA and the enhanced sedimentation by ATP synergistically removed turbidity and algae from the water efficiently.In short,atp-st-CTA as a talented material has a notable prospect in applications of water treatment owing to its advantages of environmental friendliness,low cost,and high efficiency.

Preparation of floating BiOCl_(0.6)I_(0.4)/ZnO photocatalyst and its inactivation of Microcystis aeruginosa under visible light

Frequent occurrence of harmful algal blooms has already threatened aquatic life and human health.In the present study,floating BiOCl_(0.6)I_(0.4)/ZnO photocatalyst was synthesized in situ by water bath method,and and applied in inactivation of Microcystis aeruginosa under visible light.The composition,morphology,chemical states,optical properties of the photocatalyst were also characterized.The results showed that BiOCl_(0.6)I_(0.4)exhibited laminated nanosheet structure with regular shape,and the light response range of the composite BZ/EP-3 (BiOCl_(0.6)I_(0.4)/ZnO/EP-3) was tuned from 582 to 638 nm.The results of photocatalytic experiments indicated that BZ/EP-3 composite had stronger photocatalytic activity than a single BiOCl_(0.6)I_(0.4)and ZnO,and the removal rate of chlorophyll a was 89.28%after 6 hr of photocatalytic reaction.The photosynthetic system was destroyed and cell membrane of algae ruptured under photocatalysis,resulting in the decrease of phycobiliprotein components and the release of a large number of ions (K^(+),Ca^(2+)and Mg^(2+)).Furthermore,active species trapping experiment determined that holes (h+) and superoxide radicals (·O_(2)-) were the main active substance for the inactivation of algae,and the p-n mechanism of photocatalyst was proposed.Overall,BZ/EP-3 showed excellent algal removal ability under visible light,providing fundamental theories for practical algae pollution control.