Charge Neutralization Mechanism Efficiency in Water with High Color Turbidity Ratio Using Aluminium Sulfate and Flocculation Index

Abstract

Most of the water supplied in Brazil comes from water streams that may have higher values for apparent color than turbidity. Treatability trials were performed for color and turbidity removal to evaluate the advantages of coagulation during the charge neutralization mechanism when compared to sweep flocculation for water with those characteristics. There were three types of trials: conventional Jar Test with raw water, with and without filtration, and in a pilot Water Treatment Plant, direct downward filtration, with synthetic water. Auxiliary equipment such as Continuous Flocculation Monitoring Equipment (CFME) and image analysis were used to evaluate the growth of flocs. In the Jar Tests experiments, similar levels of color (61.49%) and turbidity (61.30%) removal were observed, with a lower dosage of coagulant (46 mg/L) in the charge neutralization mechanism compared to the ones with sweep flocculation (58.22% for color and 54.73% for turbidity removal with 52 mg/L of aluminium sulfate). Similar results were found on pilot plant. At filtration rates of 180 and 300 m3 m−2 day−1, sweep flocculation mechanism had shorter filtration cycle (<5 m3) compared to other mechanisms. Therefore, a change in the operation of Water Treatment plants that use a coagulant dosage associated with sweep flocculation can bring advantages such as the reduction of coagulant consumption and sludge productions, as well as the increase of chlorine disinfection and filtration cycles.

Recent Achievements in Polymer Bio-Based Flocculants for Water Treatment

“…In other works, flocculation index (FI) is proposed for process estimation [ 55 , 56 ]. FI is defined in different ways.…”

“…Cruz et al [ 56 ] described Continuous Flocculation Monitoring Equipment based on suspension flow meter using light of 900 nm wavelength. Two values were determined: stable component (DC) of electrical output from photodetector, corresponding to the average intensity of transmitted light, and variable component (AC) caused by a random change of the size and number of particles.…”

“…Absorption spectroscopy is also used for estimation of water shade. For example, determination of absorbance at 465 nm allows precise determination of bluish color, which cannot be assessed with the naked eye [ 56 ].…”

Hierarchical Structure of Magnetic Nanoparticles -Fe₃O₄- Ferrofluids Revealed by Small Angle X-Ray Scattering

“…The existence of a larger aggregate size at a higher pH value can be explained as the charge neutralization phenomenon [17][18]. As explained before, the MNPs Fe3O4 are highly positively charged in low pH, and with the increasing of pH the positive charge will decrease until the point of zero charges.…”

Coagulation-Flocculation of Aquaculture Wastewater Using Green Coagulant from Garcinia kola Seeds: Parametric Studies, Kinetic Modelling and Cost Analysis

“…It is known that an increase of coagulant dosage would either increase or decrease the zeta potential, which will stabilise or destabilise, respectively, the suspended particles. The relationship between optimum dose and reduction (%) sheds light on the role of the sweep flocculation process mechanism [53,54]. Furthermore, the low optimal dosage obtained with GKC suggests that the neutralisation and adsorption mechanism is the primary mechanism in the treatment process [54,55].…”