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

2014 ◽  
Vol 70 (12) ◽  
pp. 1907-1912 ◽  
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.

Effects of raw diatomite on coagulation performance and residual aluminum during the micropolluted raw water treatment with polyaluminum chloride

2015 ◽  
Vol 15 (5) ◽  
pp. 918-923 ◽  
Author(s):  
W. C. Hu ◽  
C. D. Wu ◽  
L. G. Liu
Keyword(s):  
Water Treatment ◽  
Organic Carbon ◽  
Pearl River ◽  
Raw Water ◽  
Polyaluminum Chloride ◽  
Coagulation Performance ◽  
Residual Aluminum ◽  
Dissolved Aluminum ◽  
Removal Efficiencies ◽  
The Pearl River

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.

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

2010 ◽  
Vol 62 (2) ◽  
pp. 330-339 ◽  
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.

Coagulation performance and floc properties of Microcystis aeruginosa in the presence of humic acid

2014 ◽  
Vol 15 (2) ◽  
pp. 339-347
Author(s):  
Peixia Cheng ◽  
Fei Ge ◽  
Xingwang Liu ◽  
Xiaoshuang Zeng ◽  
Biao Chen
Keyword(s):  
Humic Acid ◽  
Microcystis Aeruginosa ◽  
Removal Efficiency ◽  
High Concentration ◽  
Polyaluminum Chloride ◽  
Charge Neutralization ◽  
Low Concentration ◽  
Chl A ◽  
Coagulation Performance ◽  
Floc Properties

Coagulation removal of algae in raw water could be significantly affected by humic acid (HA). A series of jar-tests were conducted to investigate the coagulation performance with polyaluminum chloride and floc properties of Microcystis aeruginosa, a unicellular cyanobacteria, in the presence of HA. Meanwhile the coagulation mechanism was explored through the measurement of zeta potential of the supernatant. The results showed that an optimal removal efficiency of chlorophyll-a (Chl-a) was obtained at pH 8.0 with a low concentration of HA (2 mg/L) and at pH 6.0 with a high concentration of HA (8 mg/L). The floc structure was more compact and bigger-sized and the calculated fractal dimension (Df) was larger at maximum coagulation efficiency. The variation of Df was consistent with that of Chl-a removal efficiency under the same coagulation conditions. Charge neutralization was inferred to be the dominant mechanism to remove algal cells with low concentration of HA, while charge neutralization, gathering and the bridging process worked together to remove algal cells with a high concentration of HA. These results provide insight on how to achieve an optimal removal efficiency of algae in the presence of different concentrations of HA in water treatment.

A Study of Reclamation of Sewage for Industrial Waters

1991 ◽  
Vol 23 (10-12) ◽  
pp. 2181-2187 ◽  
Author(s):  
Kee Kean Chin ◽  
Say Leong Ong
Keyword(s):  
Heavy Metals ◽  
Reverse Osmosis ◽  
Cellulose Acetate Membrane ◽  
Water Reclamation ◽  
Raw Water ◽  
Sand Filtration ◽  
Carbon Adsorption ◽  
Activated Sludge System ◽  
Coagulation And Flocculation ◽  
Treatment Train

The performance of a 480 cubic metres per day water reclamation plant was evaluated. The treatment train of this plant was sand filtration or carbon adsorption −0.45 µm cartridge filtration - reverse osmosis desalting - zeolite ion exchange deionisation. The raw water used was reclaimed sewage which had been treated by the activated sludge system and polished by chemical coagulation and flocculation, multimedia sand filtration and chlorination. After the reverse osmosis step using the spiral wound cellulose acetate membrane most of the cations, anions and heavy metals present in the water were removed.

Treatment of taste and odor material by oxidation and adsorption

2004 ◽  
Vol 49 (9) ◽  
pp. 289-295 ◽  
Author(s):  
S.-W. Jung ◽  
K.-H. Baek ◽  
M.-J. Yu
Keyword(s):  
Drinking Water ◽  
Raw Water ◽  
Initial Concentration ◽  
Blue Green Algae ◽  
Jar Test ◽  
Treatment Processes ◽  
Taste And Odor ◽  
Removal Efficiencies ◽  
Run Time ◽  
Lab Test

Massive blooms of blue-green algae in reservoirs produce the musty-earthy taste and odor, which are caused by compounds such as 2-MIB and geosmin. 2-MIB and geosmin are rarely removed by conventional water treatment. Their presence in the drinking water, even at low levels (ng/L), can be detected and it creates consumer complaints. So those concentrations have to be controlled as low as possible in the drinking water. The removals by oxidation (O3, Cl2, ClO2) and adsorption (PAC, filter/adsorber) were studied at laboratory and pilot plant (50 m3/d) to select suitable 2-MIB and geosmin treatment processes. The following conclusions were derived from the study. Both of the threshold odor levels for 2-MIB and geosmin appeared to be 30 ng/L as a consequence of a lab test. For any given PAC dosage in a jar-test, removal efficiencies of 2-MIB and geosmin were increased in proportion to PAC dosage and were independent of their initial concentration in raw water for the tested PAC dosages. In comparison of geosmin with 2-MIB, the adsorption efficiency of geosmin by PAC was superior to that of 2-MIB. The required PAC dosages to control below the threshold odor level were 30 mg /L for geosmin and 50 mg/L for 2-MIB at 100 ng/L of initial concentration. Removal efficiencies of odor materials by Cl2, ClO2, and O3 were very weak under the limited dosage (1.5 mg/L), however increased ozone dosage (3.8 mg O3/L) showed high removal efficiency (84.8% for 2-MIB) at contact time 6.4 minutes. According to the initial concentrations of 2-MIB and geosmin, their removal efficiencies by filter/adsorber differed from 25.7% to 88.4%. For all those, however, remaining concentrations of target materials in finished waters were maintained below 30 ng/L. The longer run-time given for the filter/adsorber, the higher the effluent concentration generated. So it is necessary that the run-time of the filter/adsorber be decreased, when 2-MIB or geosmin occurs in raw water.

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