As an efficient inorganic polymer flocculant, polyferric sulfate plays an important role in the field of sewage treatment. However, due to the significant differences in water quality characteristics and pollutant composition between industrial sewage and domestic sewage, the application of polyferric sulfate in the treatment of these two types of sewage is also different.
In terms of treatment principle, polyferric sulfate uses a variety of high-valent polynuclear complex ions produced by its hydrolysis in the treatment of industrial and domestic sewage. Through a series of actions such as compression of the double electric layer, electrical neutralization, adsorption bridging and sediment capture, the colloidal particles and suspended matter in the sewage are destabilized, condensed and precipitated, thereby achieving the purpose of purifying water quality. However, due to the complex composition of industrial sewage, it may be necessary to pay more attention to the chemical transformation and removal mechanism of certain special pollutants during treatment; while the composition of domestic sewage is relatively simple, and the application of treatment principles focuses more on conventional flocculation and precipitation processes.
In terms of pollutant targeting, industrial sewage often contains a large amount of heavy metal ions (such as copper, nickel, lead, etc.), organic pollutants (such as phenols, benzene compounds) and high concentrations of inorganic salts. Polyferric sulfate can react chemically with heavy metal ions to generate insoluble hydroxide precipitates, and at the same time adsorb and flocculate some organic pollutants to separate pollutants. The main pollutants in domestic sewage are organic matter (expressed as chemical oxygen demand COD and biochemical oxygen demand BOD), nitrogen and phosphorus nutrients, and suspended solids. Polyferric sulfate mainly targets these conventional pollutants in domestic sewage treatment, reduces the turbidity of sewage through flocculation, removes most suspended organic matter, and has a certain auxiliary removal effect on nitrogen and phosphorus.
In terms of dosage, industrial sewage usually requires a larger dose of polyferric sulfate to achieve the ideal treatment effect due to its high pollutant concentration and complex composition. Moreover, the optimal dosage of polyferric sulfate for industrial sewage in different industries varies greatly, and needs to be determined through a large number of experiments and actual operation data. In contrast, the water quality of domestic sewage is relatively stable, the pollutant concentration is relatively low, and the dosage of polyferric sulfate is relatively small and narrow. It can generally be preliminarily determined according to empirical formulas or small-scale tests, and fine-tuned in actual operation.
The process conditions of the treatment process are also different. During the treatment of industrial wastewater, it may be necessary to make complex adjustments to the treatment process according to the acidity, alkalinity, temperature, and pollutant characteristics of the wastewater. For example, for highly acidic industrial wastewater, it may be necessary to first neutralize and adjust it before adding polyferric sulfate; some high-temperature industrial wastewater needs to be cooled before flocculation treatment. The domestic sewage treatment process is relatively mature and fixed. Generally, polyferric sulfate can be added and subsequently treated at room temperature and near-neutral conditions, and the control of process conditions is relatively simple.
In terms of sludge treatment, the sludge produced after industrial sewage is treated with polyferric sulfate contains a large amount of heavy metals and difficult-to-degrade organic matter, which makes it difficult to treat and dispose of. Special sludge treatment technologies, such as sludge solidification and incineration, are required to prevent secondary pollution. The sludge produced by domestic sewage treatment has a high organic matter content and is relatively easy to be utilized as a resource by anaerobic fermentation, composting, etc. However, due to the use of polyferric sulfate, the iron content of the sludge increases, which also has a certain impact on the subsequent resource treatment process and product quality.
The application of polyferric sulfate in industrial sewage and domestic sewage treatment has similar treatment principles, but there are obvious differences in pollutant targeting, dosage, process conditions and sludge treatment. In practical applications, it is necessary to reasonably select and optimize the use of polyferric sulfate according to the specific characteristics of sewage to achieve the goal of efficient, economical and environmentally friendly sewage treatment.
