Overcoming the drawbacks of natural coagulants for drinking water treatment

2007 ◽  
Vol 7 (4) ◽  
pp. 87-93 ◽  
Author(s):  
K. Ghebremichael
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Ion Exchange ◽  
Crude Extract ◽  
Exchange Process ◽  
Drinking Water Treatment ◽  
Animal Origin ◽  
Nutrient Loads ◽  
Natural Coagulants ◽  
The Impact

A number of natural coagulants from plants or animal origin can be effectively used for the treatment of drinking water. Some are used at household levels in traditional systems using crude (non-purified) extract. In the crude extract form, natural coagulants release organic and nutrient loads to the water resulting in poor treated water quality. In such cases it becomes necessary to purify the coagulant component from the crude extract before using it for water treatment. This paper discusses an effective and simple purification of the coagulant from Moringa oleifera seed using an ion exchange method that would overcome the drawbacks of natural coagulants. The impact of the purification process on reducing organic and nutrient release was studied. Adsorption and elution parameters of the ion exchange process were optimised. The study indicated that the purified protein has effective coagulation activity and it did not release organic and nutrient loads to the water. Compared to other purification methods used in previous studies, this is simple and of comparatively lower cost. This purification method can be readily scaled up and applied even in remote parts of developing countries. This work suggests that the concerns of natural coagulants can be overcome by simple purification and this is believed to promote their use in drinking water treatment.

scholarly journals Coagulation/flocculation prior to low pressure membranes in drinking water treatment: a review

2020 ◽  
Vol 6 (11) ◽  
pp. 2993-3023
Author(s):  
Tyler A. Malkoske ◽  
Pierre R. Bérubé ◽  
Robert C. Andrews
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Membrane Fouling ◽  
Drinking Water Treatment ◽  
Low Pressure ◽  
Floc Properties ◽  
The Impact

Coagulation/flocculation has been grouped into three typical configurations and the impact of each examined in terms of floc properties and membrane fouling.

scholarly journals Bacterial Colonization of Pellet Softening Reactors Used during Drinking Water Treatment

2010 ◽  
Vol 77 (3) ◽  
pp. 1041-1048 ◽  
Author(s):  
Frederik Hammes ◽  
Nico Boon ◽  
Marius Vital ◽  
Petra Ross ◽  
Aleksandra Magic-Knezev ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Organic Carbon ◽  
Bacterial Colonization ◽  
Flow Cytometric Analysis ◽  
Drinking Water Treatment ◽  
Strong Base ◽  
Water Treatment Process ◽  
Chemically Induced ◽  
The Impact

ABSTRACTPellet softening reactors are used in centralized and decentralized drinking water treatment plants for the removal of calcium (hardness) through chemically induced precipitation of calcite. This is accomplished in fluidized pellet reactors, where a strong base is added to the influent to increase the pH and facilitate the process of precipitation on an added seeding material. Here we describe for the first time the opportunistic bacterial colonization of the calcite pellets in a full-scale pellet softening reactor and the functional contribution of these colonizing bacteria to the overall drinking water treatment process. ATP analysis, advanced microscopy, and community fingerprinting with denaturing gradient gel electrophoretic (DGGE) analysis were used to characterize the biomass on the pellets, while assimilable organic carbon (AOC), dissolved organic carbon, and flow cytometric analysis were used to characterize the impact of the biological processes on drinking water quality. The data revealed pellet colonization at concentrations in excess of 500 ng of ATP/g of pellet and reactor biomass concentrations as high as 220 mg of ATP/m3of reactor, comprising a wide variety of different microorganisms. These organisms removed as much as 60% of AOC from the water during treatment, thus contributing toward the biological stabilization of the drinking water. Notably, only a small fraction (about 60,000 cells/ml) of the bacteria in the reactors was released into the effluent under normal conditions, while the majority of the bacteria colonizing the pellets were captured in the calcite structures of the pellets and were removed as a reusable product.

Effects of ion exchange resin pre-treatment on GAC adsorption

2008 ◽  
Vol 8 (2) ◽  
pp. 181-187
Author(s):  
B. Sani ◽  
L. Rossi ◽  
C. Lubello ◽  
S. Zacchei
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Ion Exchange ◽  
Drinking Water Treatment ◽  
Life Time ◽  
Ion Exchange Resins ◽  
Dissolved Organics ◽  
Pre Treatment ◽  
Exchange Resins ◽  
By Products

In Italian drinking water treatment plants (DWTP), the problem of chlorination by-products control is very important as the Italian drinking water regulations (Dlgs. 31/2001, as enactment of the CEU directive 98/83) set very strict limits for these compounds. A possible strategy for controlling the concentrations of DBPs (disinfection by-products) is the application of treatment processes able to reduce the concentration of dissolved organic matter, the main precursor of DBPs, before the dosage of chlorine-based disinfectants. Recently, ion exchange resins for the removal of dissolved organics have shown several applications in drinking water treatment. In this experimental study, the treatment with ion exchange resins MIEX®DOC and the treatment with GAC (granular activated carbon) were evaluated for the removal of dissolved organics. Moreover, the effects of MIEX® pre-treatment on the subsequent GAC filtration phase were evaluated, with particular attention to the effects on the life-time of the GAC filter. The GAC filter operation was simulated by rapid small scale column tests (RSSCT), which allow the evaluation of the GAC breakthrough curve in a shorter time with respect to a full plant and pilot plant trials. On the basis of the experimental results, the ion exchange process was very efficient in dissolved organics removal (60–70% UV254 removal). Moreover, the results indicated that the application of ion exchange resins as pre-treatment in a conventional drinking water treatment train could increase the filter life-time in the subsequent GAC adsorption phase (about 200%) resulting in potentially important cost benefits for the overall treatment process.

scholarly journals Application of Coagulation–Membrane Rotation to Improve Ultrafiltration Performance in Drinking Water Treatment

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 643
Author(s):  
Hongjian Yu ◽  
Weipeng Huang ◽  
Huachen Liu ◽  
Tian Li ◽  
Nianping Chi ◽  
...  
Keyword(s):  
Shear Stress ◽  
Drinking Water ◽  
Water Treatment ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Drinking Water Treatment ◽  
Permeate Flux ◽  
Organic Removal ◽  
Cake Layer ◽  
The Impact

The combination of conventional and advanced water treatment is now widely used in drinking water treatment. However, membrane fouling is still the main obstacle to extend its application. In this study, the impact of the combination of coagulation and ultrafiltration (UF) membrane rotation on both fouling control and organic removal of macro (sodium alginate, SA) and micro organic matters (tannic acid, TA) was studied comprehensively to evaluate its applicability in drinking water treatment. The results indicated that membrane rotation could generate shear stress and vortex, thus effectively reducing membrane fouling of both SA and TA solutions, especially for macro SA organics. With additional coagulation, the membrane fouling could be further reduced through the aggregation of mediate and macro organic substances into flocs and elimination by membrane retention. For example, with the membrane rotation speed of 60 r/min, the permeate flux increased by 90% and the organic removal by 35% in SA solution, with 40 mg/L coagulant dosage, with an additional 70% increase of flux and 5% increment of organic removal to 80% obtained. However, too much shear stress could intensify the potential of fiber breakage at the potting, destroying the flocs and resulting in the reduction of permeate flux and deterioration of effluent quality. Finally, the combination of coagulation and membrane rotation would lead to the shaking of the cake layer, which is beneficial for fouling mitigation and prolongation of membrane filtration lifetime. This study provides useful information on applying the combined process of conventional coagulation and the hydrodynamic shear force for drinking water treatment, which can be further explored in the future.

Partial demineralisation of drinking water using carbon dioxide regenerated ion exchangers

2002 ◽  
Vol 2 (1) ◽  
pp. 57-62 ◽  
Author(s):  
W.H. Höll ◽  
K. Hagen
Keyword(s):  
Carbon Dioxide ◽  
Water Quality ◽  
Drinking Water ◽  
Water Treatment ◽  
Cation Exchanger ◽  
Low Cost ◽  
Exchange Process ◽  
Drinking Water Treatment ◽  
Acidic Cation Exchanger ◽  
Ion Exchange Process

CARIX is an ion exchange process which usually applies a mixed bed consisting of a weakly acidic and a strongly basic exchanger material. Carbon dioxide is applied as the only chemical for regeneration of the exchangers. As a consequence, the effluent contains only the amount of salt eliminated during the service cycle. CARIX allows a combined partial softening/dealkalisation/sulfate/nitrate of drinking water. A modification of the process uses exclusively a weakly acidic cation exchanger and allows a softening/dealkalisation. The process has been realised for drinking water treatment in five full-scale plants in Germany. Results of operation demonstrate that an excellent water quality is provided at fairly low cost.

Estradiol Uptake in a Combined Magnetic Ion Exchange - Ultrafiltration (MIEX-UF) Process During Water Treatment

2017 ◽  
Vol 23 (2) ◽  
pp. 328-337 ◽  
Author(s):  
Alessandra Imbrogno ◽  
Jennifer Biscarat ◽  
Andrea Iris Schafer
Keyword(s):  
Drinking Water ◽  
Humic Acid ◽  
Water Treatment ◽  
Surface Water ◽  
Ion Exchange ◽  
Acid Concentration ◽  
Drinking Water Treatment ◽  
Polymeric Materials ◽  
Aquatic Life ◽  
Magnetic Ion

Background: Estrogens and their synthetic analogues are widely used as pharmaceuticals. Upon oral administration these drugs are eventually excreted via urine. The persistence of these pharmaceuticals and inefficient removal by water treatment lead to accumulation in surface water and effluents with negative effects for aquatic life and human health. Methods: In this study, the uptake of estradiol by a combined magnetic ion exchange resin - ultrafiltration process (MIEX-UF) was investigated. This is a relatively common process used in drinking water treatment for the removal of natural organic matter. However, uptake of micropollutants, such as steroidal pharmaceuticals, may occur as a side effect of water treatment due to the high affinity for polymeric materials. To elucidate the mechanism governing estradiol partitioning between water, resin and membrane, the influence of different parameters, such as pH, humic acid concentration and membrane molecular-weight-cut-off (MWCO) was studied. Results: Humic acid concentration and pH affected estradiol uptake most. At pH 11 the most significant increase of estradiol uptake was observed for MIEX-UF process (30 ng/g corresponding to 80%) compared with individual UF (17 ng/g corresponding to 12%). The presence of humic acid slightly reduced estradiol uptake at pH 11 (about 55%) due to competition for the ion exchange binding sites. Conclusion: Results demonstrated that the uptake of estradiol, which is amongst the most potent EDCs detected in surface water, in the MIEX-UF process can reach significant quantities (30 ng/g of resin) leading to uncontrolled accumulation of this micropollutant during drinking water treatment. This study gives a novel contribution in the understanding the mechanism of the unanticipated accumulation of pharmaceuticals, such as estradiol, in the drinking water treatment process.

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