On the importance of pH value in coagulation | Journal of Water Supply: Research and Technology-Aqua (2024)

FAQs

How does pH affect coagulation and turbidity? ›

In the enhanced coagulation process, the adjustment of pH is an important way to improve turbidity and NOM removal efficiency (Gregory and Carlson, 2003). Previous studies have given the optimum pH range 5.0–6.5 for aluminum coagulants and 4.5–6.0 for ferric coagulants (Matilainen et al., 2010).

The pH of the water plays an important role when alum is used for coagulation because the solubility of the aluminum species in water is pH dependent. If the pH of the water is between 4 and 5, alum is generally present in the form of positive ions (i.e., Al(OH)2+, Al8(OH)4+, and Al3+).

pH affects most chemical and biological processes in water. It is one of the most important environmental factors limiting species distributions in aquatic habitats. Different species flourish within different ranges of pH, with the optima for most aquatic organisms falling between pH 6.5-8.

One fundamental parameter that significantly influences the efficiency and performance of these treatment systems is the pH level of the water being treated. The pH level affects both the chemical and physical properties of the water, thereby influencing the behavior of contaminants and treatment processes.

Coagulation is often more effective in high turbidity water (>100 NTU) than in lower turbidity water (5–10 NTU) because of higher collision frequencies, increased van der Waals attractions, and faster aggregation [22], [23], [24].

[22] , the optimal pH range of turbid water for efficient functioning of natural coagulants varies between 5 and 8. Inorganic compounds, algal cells and most organic compounds, amongst other materials causing turbidity, are effectively eliminated within this pH range.

A metal based coagulant will consume alkalinity, especially in a well buffered high pH water, which could compromise the softening process. The best coagulant is therefore a pre-hydrolysed species with a high basicity. PACl has been found to be very suitable for lime softening applications.

According to previous research [18] , by increasing the pH value (alkaline condition) will reduce the turbidity value. At higher pH value, there is a reduction of turbidity because of the tendency toward sedimentation due to the opposite charge of an ion of the colloid. ...

TOC or NOM reductions depend on the type and dosage of coagulant, the pH, temperature, raw water quality and NOM characteristics. In general, the optimum pH for ferric salts is in the range 3.7 to 4.2, and for aluminum sulfate in the range 5.0 to 5.5.

pH is an important parameter for assessing the health of a waterbody. pH changes can indicate external stresses such as acid rain or discharges. pH can predict what kinds of chemicals can be released from the sediment into the water column.

What is pH and why is it important? ›

pH is how we measure how acidic or alkaline an aqueous solution is. Pure water has a pH value of 7.0, however, not all water solutions are set at this value. Many contributing factors affect the pH of a solution which is why it is so important to constantly monitor pH levels in a variety of industries.

How does pH affect water quality? The pH of water can affect its taste, odor, and color, making it less appealing for human consumption. Water with a high pH may also be corrosive and cause damage to pipes and plumbing systems.

The pH scale helps scientists measure whether or not a solution is acidic or basic. In chemistry, a solution is defined by one substance being dissolved in another. Solutions are easiest to understand as a liquid, but it is important to note that they also exist in gas and solid forms.

Results of our studies indicate that the final effect of the coagulation of the dyes depends on the coagulant dosage as well as pH value. The best results in colour removal were noted for acid medium (i.e. pH range between 3.5-5.5).

Milk coagulates spontaneously at various pH zones, insoluble casein salts being formed between pH 2.0 and 3.0, isoelectric casein at pH 4.7 and calcium caseinate at about pH 6.5. Optimum rennet coagulation is at about pH 6.0 coinciding with complete conversion of casein to paracasein.

Reducing milk pH to 6.3 caused a significant decrease in coagulation time but a less marked increase in curd firmness.

The factors that influence coagulation–flocculation are, among others, temperature, pH, effluent quality, dosage and coagulant type (Nnaji 2012; Jin 2005; Ma et al. 2001). The suspended particles vary considerably in source, composition charge, particle size, shape, and density.