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PAC Coagulation Sedimentation Method
Oct 23, 2017

PAC Coagulation sedimentation method

The origin and nature of coking wastewater

Coking wastewater is coal coke, gas purification, and coking products in the recovery process of waste water. Its pollution components contain ammonia, cyanide, thiocyanate and other inorganic pollutants and phenol, naphthalene, anthracene, quinoline, isoquinoline, indole, pyridine and other difficult to degrade organic pollutants. Among these complex pollutants lead to coking wastewater into a COD value, phenol value, ammonia nitrogen value is extremely difficult to deal with industrial wastewater. And coking wastewater contains many toxic and potentially carcinogenic substances, if not effectively treated, direct large-scale emissions, will seriously pollute the ecological environment and endanger the healthy life of mankind.

Deep processing of coking wastewater

2.1 Physical law

2.1.1 Coagulation sedimentation method

Coagulation and sedimentation is one of the commonly used methods in industrial wastewater treatment. It can remove the waste water turbidity, color, and a variety of toxic and harmful pollutants. The coagulation process refers to the process by which the fine particles or colloidal particles in the water are gradually growing under the action of the coagulant and eventually precipitated from the water. The properties of the granules, the hydrolyzate of the coagulant, and the degree of interaction between the two will affect the effect of coagulation and sedimentation.

At present, in the coagulation precipitation polymerization of ferric sulfate (pFS), polyacrylamide (PAM), poly aluminum chloride is the application of more coagulants.

Xiao Linbo et al. Studied the effects of the addition of polyaluminum chloride (pAC) and poly (ferric sulfate) (pFS) on the removal efficiency of COD and chroma in coking wastewater. The optimum coagulation conditions were as follows: PAC dosage was 6g / L, pH value was 7, PFS dosage was 5.5g / L, pH value was 7. Under the optimum coagulation conditions, the removal rate of CODcr was 44.83% and the decolorization rate was 80%. The removal rate of CODcr was 38.71% and the decolorization rate was 80%. PAC removal of CODcr effect than PFS good; and decolorization effect of the same two. Polyacrylamide is often used as a coagulant.

In the traditional coagulation and sedimentation method, the amount of coagulant input is large, and some single system coagulant after use in the water will be part of the residual, after the row of the environment and the human body will bring harm. So in order to more effectively deal with coking wastewater, flocculant mixed use can be seen. (PFS), aluminum sulfate (Al2 (sO4) 3) and polyacrylamide (PAM) were used to study the coking wastewater. The results showed that the treatment of wastewater with PFS and PAM was the most The removal rate was 73.08% and 62.22%, respectively. The optimum conditions were pH = 5 and the dosage was (40 + 6) mg / L, the CODcr was 68mg / L and the removal rate was 73.08% and 62.22% respectively.

2.1.2 Adsorption method

Adsorption method in the wastewater treatment commonly used adsorbents are activated carbon, diatomaceous earth, slag and so on. The principle of the wastewater treatment by adsorption is to use the porous surface of the adsorbent to adsorb one or more solutes in the wastewater to achieve the purpose of removing some solute and to treat the waste water. Adsorption method on the hardness, ammonia, COD and suspended solids have a removal effect on the COD and suspended solids removal effect is better.

Activated carbon is the most commonly used class of adsorbents, but because the activated carbon regeneration system is difficult to operate, the device cost is high, so it has not been widely promoted. China's fly ash emissions, more than 100 million tons per year, fly ash under certain conditions with flocculation sedimentation and filtration, which as an adsorbent to provide the conditions for wastewater treatment, while solving the regeneration problem,