The effect of polymeric flocculants on floc strength and filter performance

2006 ◽  
Vol 53 (7) ◽  
pp. 77-85 ◽  
Author(s):  
M.M. Rawlings ◽  
C.S.B. Fitzpatrick ◽  
J. Gregory ◽  
A. Wetherill

Polymeric flocculants are widely used throughout the water industry as flocculant aids, they are known to increase floc density and aid settlement in the clarification stage of the water treatment process. In this research, polymeric flocculants were used to improve floc strength prior to filtration on a dissolved air flotation (DAF) plant in an attempt to prevent filter breakthrough. A modified jar test procedure using a PDA (photometric dispersion analyser) optical flocculation monitor was developed in order to evaluate the system floc strength. Filtration trials were carried out on a pilot filter rig situated on a surface water treatment works in Yorkshire. The filter feed originated from the main plant filter channel. Filter performance was assessed by continuous online monitoring of effluent particle counts, turbidity and headloss over the period of the filter run. Results indicated that low doses of polymeric flocculants had a beneficial effect on filtered water quality, as measured by particle counts, turbidity, UV254 absorption and dissolved organic carbon (DOC). Polymeric flocculants also had the effect of extending filter run length. The modified jar test results indicated that the flocculants used improved the floc strength and enhanced reflocculation of the micro flocs present after the flotation process.

2021 ◽  
Vol 9 (01) ◽  
pp. 512-524
Author(s):  
Konan Lopez Kouame ◽  
◽  
Nogbou Emmanuel Assidjo ◽  
Andre Kone Ariban ◽  
◽  
...  

This article presents an optimization of the drinking water treatment process at the SUCRIVOIRE treatment station. The objective is to optimize the coagulation and flocculation process (fundamental process of the treatment of said plant)by determining the optimal dosages of the products injected and then proposes a program for calculating the optimal dose of coagulant in order to automatically determine the optimal dose of the latter according to the raw water quality. This contribution has the advantage of saving the user from any calculations the latter simply enters the characteristics of the raw effluent using the physical interface of the program in order to obtain the optimum corresponding coagulant concentration. For the determination of the optimal coagulant doses, we performed Jar-Test flocculation tests in the laboratory over a period of three months. The results made it possible to set up a polynomial regression model of the optimal dose of alumina sulfate as a function of the raw water parameters. A program for calculating the optimal dose of coagulant was carried out on Visual Basic. The optimal doses of coagulant obtained vary from 25, 35, 40 and 45 mg/l depending on the characteristics of the raw effluent. The model obtained is: . Finally, verification tests were carried out using this model on the process. The results obtained meet the WHO drinkability standards for all parameters for a settling time of two hours.


2006 ◽  
Vol 53 (7) ◽  
pp. 217-223 ◽  
Author(s):  
M.A. Yukselen ◽  
J. Gregory ◽  
E. Soyer

The effect of shear on the formation and break-up of flocs generated using cationic, anionic and non-ionic polymers, and dual combinations of these, has been investigated using conventional jar test procedure and by continuous optical monitoring. The breakage of flocs was followed at a high stirring speed, corresponding to average shear rate (G) of approximately 520 s−1. Most of the breakage occurred within a few seconds of increasing the shear rate. After each breakage, the stirring rate was reduced to the original value of 50 rpm (G≈23 s−1) to allow the flocs to regrow. For cationic–anionic polymers case, the regrowth of flocs was fully reversible and the breakage factors were smallest indicating highest floc strength. In contrast, flocs formed using non-ionic polymer together with anionic or cationic did not produce as strong flocs. It is found that the sequence of polymer addition is not very significant for floc formation and reformation when the cationic–anionic dual system is used.


Author(s):  
Sedolfo Carrasquero ◽  
María Fernanda Martínez ◽  
María Gabriela Castro ◽  
Altamira Díaz ◽  
Gilberto Colina

  Los coagulantes químicos inorgánicos son los más usados actualmente en el proceso de potabilización; sin embargo, a través de estudios se ha demostrado que los mismos tienen un efecto perjudicial en la salud de los seres humanos. El objetivo de la investigación fue evaluar la eficiencia de las semillas de tamarindo (Tamarindus indica) como coagulante natural en el proceso de potabilización de las aguas. Se usó el ensayo de jarras para simular el proceso de coagulación, floculación y sedimentación, y determinar la efectividad del preparado con semillas, sin desgrasar y desgrasadas, y compararla con la correspondiente al coagulante químico. Se preparó agua turbia sintética (5000 mg/L) utilizando caolín en agua de grifo, se midieron los parámetros: turbidez, pH, color, alcalinidad total, sólidos totales, antes y después de la aplicación de distintas dosis del preparado con semillas (10; 25; 50; 100; 250 y 500 mg/L) en soluciones con diferentes valores de turbidez (10, 15, 25, 50, 75, 100 y 200 UNT). El uso de las semillas de tamarindo sin desgrasar como coagulante en aguas de 200 UNT permitió obtener valores residuales de turbidez menores a los establecidos por las normas sanitarias venezolanas de calidad del agua (5 UNT), con porcentajes promedios de remoción de 97,6%. Sin embargo, en aguas de media (50-75 UNT) y baja turbidez (15 UNT), las aguas tratadas presentaron valores superiores al límite establecido. Con respecto al color, sólidos totales, alcalinidad total y pH, los valores después del tratamiento fueron 10 UC Pt-Co, 150 mg/L, 75 mg CaCO3/L, y 6,79, respectivamente, por lo que la semilla de tamarindo puede ser utilizada con éxito como coagulante en la potabilización de aguas.   Palabras clave: Tamarindus indica, sulfato de aluminio, coagulantes naturales, potabilización.   Abstract   Currently, chemical origins coagulants are used in water purification processes; however, it has been shown through different studies that they have a detrimental effect on the health of humans. The objective of this research is to evaluate the efficiency of seed extract of tamarind as a natural coagulant in water treatment process. A jar test was used in order to simulate the coagulation, flocculation and sedimentation processes. A synthetic turbid water using kaolin in tap water was prepared. The parameters turbidity, pH, color, alkalinity and total solids were measured before and after the application of natural coagulant at different doses (25; 50; 100; 250 and 500 mg/L) in solutions with different initial turbidity (10, 15, 25, 50, 75, 100 and 200 NTU). The use of Tamarindus indica seeds without fat and oils in water of 200 TNU allowed to obtain turbidity residuals values lower than those established by the Venezuelan sanitary norms of water quality (5 NTU) with average removal percentages of 97.6%. However, in waters of medium (50-75 TNU) and low turbidity (15 NTU), the treated waters presented values above the established limit. With respect to color, total solids, total alkalinity and pH, the values after the treatment were 10 CU Pt-CO, 150 mg/L, 75 mg CaCO3/L and 6.79, respectively, so the tamarind seed can be used as a coagulant in water purification.   Key words: coagulant, water treatment, Tamarindus indica, kaolin, aluminum sulfate.


2019 ◽  
Vol 5 (1) ◽  
pp. 29-38
Author(s):  
Aziz Qannaf Zaid ◽  
Suriati Ghazali ◽  
Noor Sabrina Ahmad Mutamim ◽  
Olalere Olusegun Abayomi ◽  
Nour Hamid Abdurahman

Inrecent times, the consumption of water for domestic and industrial use has been on an increasing trend with a rise in demand. Therefore, a need for a plant-based alternative of water treatment process at a lower cost using an environmentally friendly approach. Moringa olifeira is an example ogf the plant-based materials usually grown in developing countries with a natural coagulating property. In this study, the Jar test was conducted to evaluate the performance of Moringa olifeira cake residue (MOCR) as biocoagulant for the treatment of water for safe drinking. The result obtained showed the lowest turbidity, pH, TDS, and water conductivity value as 4.7 NTU (0.75 mg/L), 5.2 (2.5 mg/L), 40 ppm (1.0 mg/L), and 50us/cm (0.50 mg/L), respectively. Moreover, the standards COD and BOD values were less than the recommended Malaysian Standard of Water Quality of 250 mg/L and 100 mg/L, respectively. Hence, MOCR therefore is a potential source for plant-based coagulating agent for water treatment for domestic drinking water.


2002 ◽  
Vol 2 (5-6) ◽  
pp. 57-63
Author(s):  
L. Rossi ◽  
C. Lubello ◽  
E. Poggiali ◽  
O. Griffini

In this experimental study the clarification process of the drinking water treatment plant (WTP) of Florence (Italy) has been evaluated. At present, the most common way to optimise the clariflocculation process (best type and dosage of coagulants and mixing conditions) is the jar-test procedure which can give information about the final turbidity, and consequently the process efficiency, after a settling period in a batch procedure at laboratory-scale. An alternative method with a Photometric Dispersion Analyser (PDA2000) was recently introduced at the WTP to provide quick and continuous information (flocculation index, correlated with the flocs size) about the aggregation state of particles during a modified jar-test procedure. The PDA2000 was applied to a real suspension (namely Arno river water) providing useful data for the determination of best type and optimum dosage of coagulants. Furthermore a strong correlation between the removal efficiency of the turbidity and PDA a parameter derived from the PDA 2000 data (defined as the rate of the square root of the flocs size index and the maximum slope of the growing curve) was observed.


2021 ◽  
Vol 3 (2) ◽  
pp. 114-119
Author(s):  
Adina Pacala ◽  
◽  
Maria Laura Samonid ◽  
Bogdan Murariu ◽  

Aluminum salts are widely used across Romania in surface water treatment as coagulants. It is well-known that the efficiency of these coagulants has a complex dependency on the nature of the raw water, being affected by temperature, pH, and suspended solids. The objective of this case study was to compare the coagulation-flocculation efficiency process of raw water from the Bega River, at low temperature and turbidity, taking into account the use of alternative coagulating agents such as alum, poly aluminum chloride (PAC), and their mixing in 1:1 ratio. The raw water samples were treated using the "Jar Test" procedure, comparable with the current plant conditions at Timisoara Waterworks and taking into account possible operational improvements. For the mixture method applied in which was combined alum and PAC in 1:1 mixing ratio were achieved lower concentrations in aluminum residual, TOC, and turbidity.


2001 ◽  
Vol 1 (2) ◽  
pp. 83-90 ◽  
Author(s):  
C. Bonneville ◽  
D.W. Smith

In May 1999, a project using a dissolved air flotation (DAF)/ozone/filtration pilot plant was started to study the effects of pre-ozonation on the flocculation of particles and removal of organic matter in an advanced treatment process. Results indicate that small doses of ozone pre-ozonation slightly improve the flocculation of particles and their subsequent removal in the DAF unit when used in conjunction with alum or PACl. However, it was found that high ozone doses impeded flocculation. More significant is ozone's benefit for the removal of UV-absorbing organic matter. The study also found that DAF is very effective at removing turbidity causing particles and colour from the water, thereby improving filter performance.


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