Enhanced coagulation for treating slightly polluted algae-containing raw water of the Pearl River combining ozone pre-oxidation with polyaluminum chloride (PAC)

The effects of raw diatomite on coagulation performance (CP) and the contents of residual aluminum (RAl) during the Pearl River water treatment with polyaluminum chloride (PAC) were investigated. Results demonstrated that the addition of raw diatomite could significantly improve the CP. The removal efficiencies (REs) of turbidity, dissolved organic carbon and UV254 could achieve 97.63%, 44.31% and 52.31%, respectively, at PAC dose of 20 mg/L and diatomite dose of 40 mg/L. Furthermore, adding appropriate dose of diatomite (less than 40 mg/L) could greatly reduce the RAl contents. The residual total aluminum and residual total dissolved aluminum both reached the lowest concentrations (0.185 mg/L and 0.06 mg/L, respectively) when the PAC dose was 15 mg/L and diatomite dose was 40 mg/L.

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Performance of PAC/PDM composite coagulants for removal of algae from Lake Taihu waters in summer

Water Science & Technology ◽

10.2166/wst.2010.292 ◽

2010 ◽

Vol 62 (2) ◽

pp. 330-339 ◽

Cited By ~ 19

Author(s):

Y. J. Zhang ◽

X. L. Zhao ◽

X. X. Li ◽

Ch. Liu ◽

L. L. Zhu

Keyword(s):

Water Quality ◽

Intrinsic Viscosity ◽

Removal Rate ◽

Lake Taihu ◽

Raw Water ◽

Removal Rates ◽

Polyaluminum Chloride ◽

Enhanced Coagulation ◽

Algae Removal ◽

Better Than

The enhanced coagulation of algae-rich raw water from Lake Taihu in summer was studied by use of composite coagulants. The composite coagulants were composed of polyaluminum chloride (PAC) and polydimethyldiallylammonium chloride (PDM) with various intrinsic viscosity values (0.55–3.99 dL/g) and different mass percentages (5–20%) in the formulation. For raw water with temperature of 28–29°C and algae content of 3.60 × 104–3.70 × 104 cells/ml, the algae-removal rates of 89.0% and 89.3–93.1% could be realized by using PAC and PAC/PDM (0.55/5%–3.99/20%) with dosages of 8.37 mg/L and 5.93–3.58 mg/L, respectively, when 2 NTU residual turbidity of treated water after sedimentation was required. Compared with using PAC only, the removal rate of CODMn using PAC/PDM increased at least 4.4% when the dosage was 8 mg/L, and increased at least 5.0% when the dosage was 10 mg/L. The composite coagulants could still function well when raw water quality deteriorated and algae content reached 8.00 × 104 cells/ml. The enhanced coagulation efficiency of PAC/PDM (0.55/5%) could be better than that of PAC combined with prechlorination process when the same dosages are used.

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The performance of enhanced coagulation for treating slightly polluted raw water combining polyaluminum chloride with variable charge soil

Water Science & Technology ◽

10.2166/wst.2014.423 ◽

2014 ◽

Vol 70 (12) ◽

pp. 1907-1912 ◽

Cited By ~ 2

Author(s):

Z. L. Zhang ◽

C. D. Wu ◽

Y. J. Wang ◽

J. C. Tang ◽

Y. P. Liu

Keyword(s):

Heavy Metals ◽

Main Mechanism ◽

Raw Water ◽

Polyaluminum Chloride ◽

Enhanced Coagulation ◽

Charge Neutralization ◽

Variable Charge ◽

Coagulation Performance ◽

Removal Efficiencies ◽

Variable Charge Soil

The feasibility and effectiveness of treating pollutants in slightly polluted raw water by variable charge soil and polyaluminum chloride (PAC) was investigated. Removal efficiencies of turbidity, phenol, aniline, algae and heavy metals (Cu2+, Zn2+ and Pb2+) were used to evaluate the coagulation performance. The results indicated that the addition of variable charge soil as a coagulant aid is advantageous due to the improvement of removal efficiencies. The tests also demonstrated that the presence of variable charge soil increased the removal of turbidity rather than adding residuary turbidity. The use of variable charge soil produced settleable flocs of greater density and bigger size. The main mechanism involved in the PAC coagulation was supposed to be sweep flocculation as well as charge-neutralization. Variable charge soil played a promoted aid role by adsorption in the enhanced coagulation process. It is concluded that the enhanced coagulation by PAC and variable charge soil, as coagulant and adsorbent, is more effective and efficient than traditional coagulation.

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