scholarly journals Cyanobacterial biomass: a striking factor to decrease polyaluminium chloride (PACl) coagulation efficiency during a successive bloom

2021 ◽  
Author(s):  
Weijun Song ◽  
Jie Zeng ◽  
Xi Li ◽  
Yu Xie ◽  
Xunfang Wu
Keyword(s):  
Water Treatment ◽  
Cell Density ◽  
Ph Value ◽  
Cyanobacterial Blooms ◽  
Water Treatment Process ◽  
Treatment Processes ◽  
Coagulation Process ◽  
Cyanobacterial Biomass ◽  
Source Waters

Abstract Occurrence of cyanobacterial blooms in source waters challenges water treatment processes. During a successive bloom, typical characteristics of elevated cell-density and pH was observed from development to maintenance stage. However, studies about their influences on coagulation process were limited. Here, PACl coagulation experiments were conducted to investigate Microcystis removal with varied pH and cell-density. Results showed that PACl coagulation alone was sufficient to remove Microcystis with low cell-density (105–106 cells mL−1), since elevated pH value (8.5–9.5) can promote PACl coagulation possibly ascribed to sweeping cells via neutral gelatinous precipitate of alum. Nevertheless, elevated cyanobacterial biomass was a striking factor to decrease Microcystis removal (80–100%) by PACl coagulation, since its inhibitory effects on coagulation process could not be offset by in situ elevated pH value. Chlorination-assisted (1 mg L−1) coagulation was recommended to treat cyanobacteria-laden source waters with high cell-density of >107 cells mL−1, as it promoted cyanobacterial removal and achieved the highest removal ratio of DOC and turbidity among these treatments. These findings would provide an important reference for water supplies to choose proper water treatment process to treat cyanobacteria-laden source waters during a successive bloom.

scholarly journals Natural agents as auxiliaries in water clarification: literature review and experimental evaluation

2020 ◽  
Vol 42 ◽  
pp. e44800
Author(s):  
João Paulo Nascimento Armeloni ◽  
Danieli Soares de Oliveira ◽  
Clainer Bravin Donadel
Keyword(s):  
Water Treatment ◽  
Literature Review ◽  
Removal Efficiency ◽  
Process Efficiency ◽  
Human Consumption ◽  
Agricultural Activity ◽  
Water And Wastewater Treatment ◽  
Turbidity Removal ◽  
Water Treatment Process ◽  
Treatment Processes

The increasing demand for water resources (primarily for human consumption and industrial and agricultural activity) is driven by socio-economic development, and population growth. Recent research has been focusing on alternative coagulants based on natural elements, as opposed to the commonly used iron and aluminum salts, for use in water and wastewater treatment processes. In this context, a thorough literature review on alternative coagulants and their application to water treatment processes has been conducted in this work. In addition, three experiments have been conducted with a widely used natural organic coagulant (Moringa oleifera). The alternative clarification system used is the helically coiled tube flocculator (HCTF), with high turbidity removal efficiency and low processing times. A comparative analysis of the turbidity reduction over time was performed with samples collected after 600, 900, 1200, 1500, 1800, 2100, 2400, and 2700 s from the hydraulic circuit. The process efficiency using the proposed alternative coagulant reached 95.3% (after 1800 s). The turbidity removal efficiency remained almost constant after 1800 s, with variations below 1%. These results prove that natural alternative agents can be powerful tools in the water treatment process, with efficiency values exceeding those obtained using chemicals (e.g., aluminum sulphate) as coagulant/ flocculant agents.

scholarly journals ENVIRONMENTAL IMPACT OF WATER TREATMENT PROCESS. A SYSTEMATIC REVIEW OF EVALUATION METHOD

2016 ◽  
Vol 22 (3) ◽  
pp. 34-39
Author(s):  
FLORINA FABIAN ◽  
VALENTIN NEDEFF ◽  
MIRELA PANAINTE -LEHADUS ◽  
OANA IRIMIA ◽  
SILVIA RACOVITA
Keyword(s):  
Systematic Review ◽  
Global Warming ◽  
Water Treatment ◽  
Environmental Impact ◽  
Carbon Footprint ◽  
Treatment Process ◽  
Environmental Indicators ◽  
Impact Categories ◽  
Water Treatment Process ◽  
Treatment Processes

In an international context in continuous development, water treatment processes become an important component of society where we live. Attention is directed on water treatment processes in the context of increasing water demand. This study proposes a systematic review of methods for the assessment of the environmental impact of Water Treatment process. The approach is based on the evaluation of LCA, Externalities Evaluation methodology and Carbon Footprint methodology, each of these methods have the environmental indicators able to relate direct and indirect emissions generated by any water treatment process. The present review compares and discusses the implementation of the above-cited methodologies to different case studies. The results in short show that Carbon Footprint only assesses the global warming potential of a water treatment plant, whereas Life Cycle Analysis and assess multiple environmental impact categories, which may include global warming, but also impacts on human health, ecosystems quality, etc. There are different standards and organizations around each assessment. The ExternE method on the contrary aims to quantify external impacts, from both economic and social points of view, to weight each endpoint of the impact categories.

Studies on Micro-Polluted Source Water Treatment by Ozone Combined Processes

2011 ◽  
Vol 281 ◽  
pp. 40-44 ◽  
Author(s):  
Jian Kun Zhang
Keyword(s):  
Water Treatment ◽  
Treatment Process ◽  
Quality Characteristics ◽  
Combined Processes ◽  
Source Water ◽  
Combined Process ◽  
Water Treatment Process ◽  
Treatment Processes ◽  
Removal Efficiencies ◽  
Better Than

According to the water quality characteristics, micro-polluted source water treatment by ozone combined processes. The results show that the average removal efficiencies of algae, CODMn, NH4+-N, turbidity, chromaticity by bio-pretreatment filter are 72.0%, 14.5%, 80.5%, 58.6% ,26.0%, respectively; while the whole average removal efficiencies by pre-ozonation tank following bio-pretreatment filter had increased at the different dosages of ozone, such as algae 12.0%, CODMn 19.5% ,NH4+-N 7.5%, turbidity 10.9%, chromaticity 34.5%, respectively; and the optimal dosages of ozone are between 0.7 and 1.5mg/L. Furthermore, compared with the conventional water treatment process, all kinds of combined water treatment processes are better than the conventional one, of which the combined process Ⅲ with granular activated carbon (GAC) adsorption tank is obviously the best, all the average removal efficiencies of algae, CODMn, NH4+-N, turbidity, chromaticity can reach 82%, while whose operation expenditure is higher than any others, so it should be considered comprehensively in the practice.

scholarly journals Water Treatment in Hybrid Connection of Coagulation, Ozonation, UV Irradiation and Adsorption Processes

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1748
Author(s):  
Beata Karwowska ◽  
Elżbieta Sperczyńska ◽  
Lidia Dąbrowska
Keyword(s):  
Water Treatment ◽  
Metal Ions ◽  
Uv Irradiation ◽  
Uv Absorbance ◽  
Treatment Processes ◽  
Coagulation Process ◽  
Organic Pollutants Removal ◽  
Adsorption Processes ◽  
Pollutants Removal ◽  
Ozonation Process

In recent years, conventional water treatment systems have been supported by ozonation or UV irradiation processes. The efficiency of four hybrid processes: (1) coagulation and adsorption, (2) ozonation and coagulation, (3) ozonation, coagulation and adsorption, (4) ozonation, UV irradiation, coagulation and adsorption of inorganic and organic pollutants removal was analysed. In the presented study, the content of organic matter in natural water was evaluated as colour, oxidisability (OXI), total and dissolved organic carbon (TOC and DOC) content and UV absorbance at the wavelength of 254 nm for natural and modified water. Additionally, removal of Ni2+, Cd2+and Pb2+ ions during the treatment processes was analysed. The coagulation process with the use of polyaluminium chloride removed 45% of colour and 39, 26% and 45% of OXI, TOC and UV absorbance, respectively. Using the ozonation before coagulation increased efficiency of colour and UV254 absorbance reduction by 33% and 25%, respectively. Coagulation with both UV irradiation and adsorption had insignificant results on the analysed factors value. The coagulation process was the most efficient for metal ions removal (40–78%). The ozonation process before coagulation increased removal up to 55–85%. Additional irradiation with UV or using of the adsorbent during coagulation of initially ozonated water had an insignificant impact on metal ions concentration in water.

scholarly journals Pollutant and Microorganism Removal From Water by Hydrodynamic Cavitation

2016 ◽  
Vol 10 (1) ◽  
pp. 258-264 ◽  
Author(s):  
Zhimeng Liu ◽  
Mengfu Zhu ◽  
Cheng Deng ◽  
Hongbo Su ◽  
Ping Chen ◽  
...  
Keyword(s):  
Reaction Time ◽  
Water Treatment ◽  
Operating Temperature ◽  
Removal Rate ◽  
Water Disinfection ◽  
Hydrodynamic Cavitation ◽  
Experimental Conditions ◽  
Water Treatment Process ◽  
Treatment Processes ◽  
Microorganism Removal

Hydrodynamic cavitation can effectively remove organic pollutants and microorganisms from water. Organic compound degradation and water disinfection removal rate is related to reaction time and operating temperature. Removal rate can be improved by increasing the reaction time or raising the operating temperature. Under our experimental conditions, the removal rate of colority, COD and petroleum pollutants was 80.0%, 72.13% and 70.00%, respectively. In addition, Escherichia coli removal rate was higher than 99.99%. As a new water treatment process, hydrodynamic cavitation can be utilized alone or in combination with other water treatment processes, showing broad application prospects.

Municipal Drinking Water Treatment Procedures for Taste and Odour Abatement – A Review

1983 ◽  
Vol 15 (6-7) ◽  
pp. 279-289 ◽  
Author(s):  
A J Montiel
Keyword(s):  
Water Treatment ◽  
Distribution System ◽  
Water Distribution ◽  
Tap Water ◽  
Drinking Water Treatment ◽  
Water Treatment Process ◽  
Treatment Processes ◽  
Oxidation Stage ◽  
Sensory Qualities ◽  
Treatment Procedures

Taste and odour of water are sensory qualities the consumers can appreciate very easily. It is of prime importance that, during the water treatment process, taste and odours be removed and that the tap water have no abnormal taste or odour. There are three sources of tastes and odours, the removal of which must be studied separately. All the odorous compounds originating in the raw water should be removed in the treatment processes which are clarification, oxidation and adsorption. During water treatment processes such as the oxidation stage (chlorination), tastes and odours may be produced and the use of such treatments must be carefully monitored. Tastes may be produced in the water distribution system by microbiological activity which must be suppressed.

Water treatment process evaluation of wildfire-affected sediment leachates

2017 ◽  
Vol 3 (2) ◽  
pp. 352-365 ◽  
Author(s):  
Amanda K. Hohner ◽  
Leigh G. Terry ◽  
Eli B. Townsend ◽  
R. Scott Summers ◽  
Fernando L. Rosario-Ortiz
Keyword(s):  
Water Treatment ◽  
Process Evaluation ◽  
Treatment Process ◽  
Water Treatment Process ◽  
Treatment Processes ◽  
Sediment Deposits ◽  
Treatment Thresholds ◽  
Runoff Events

Re-suspension of post-fire sediment deposits challenge conventional water treatment processes during runoff events, impacting DBP formation. Treatment thresholds for a range of unit processes are established.

Settling characteristics of problem algae in the water treatment process

2006 ◽  
Vol 53 (7) ◽  
pp. 113-119 ◽  
Author(s):  
S.K. Choi ◽  
J.Y. Lee ◽  
D.Y. Kwon ◽  
K.J. Cho
Keyword(s):  
Water Treatment ◽  
Treatment Process ◽  
Settling Velocity ◽  
Stationary Growth Phase ◽  
Stationary Growth ◽  
Fluorometric Method ◽  
Water Treatment Process ◽  
Treatment Processes ◽  
Synedra Acus ◽  
Settling Column

The settling velocity or removal rates of problem algae in the water treatment process and their flocculants were measured with settling column (SETCOL) and fluorometric method. Our research who were centred on the algal density and shape affecting the settling. The settling velocities of large algae ranged from 0.1 cm/h to 2.6 cm/h, whereas those of small algae were below 1.0 cm/h. The settlings of algae in the stationary growth phase significantly increased and dead algae corresponded with the declining algae. The extent of deformation, which was expressed as the coefficient of form resistance of the algae had the great influences upon the settling. The most extreme deformed algae were needle-shaped ones like Synedra acus, which was known to be a problem in water treatment processes in Korea. Changes in the settling velocity of algae were correlated with algal volume and morphology rather than cell density.

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