Regarding the selection of inorganic flocculants, most of them should be selected according to the water quality, which is actually very simple, as long as you remember a few points.
1. Industrial sewage, waste water, municipal sewage are generally selected industrial grade polyaluminum chloride, the content is divided into 26-28%, usually waste water treatment is used 26% content, municipal sewage is recommended to use 28% content, the amount of sludge generated will be relatively small.
2. Choose 28%-30% polyaluminum chloride content for water reuse.
3. Drinking water, tap water, industrial water, power plant raw water, industrial circulating water, etc., all choose to use 30% content, 30% content of polyaluminum chloride is the national drinking water standard, the reason for the use of industrial water, power plant raw water, industrial circulating water is less sludge and higher treatment efficiency.
4. Domestic sewage or sewage with high phosphorus content but good biochemical properties, choose aluminum sulfate, aluminum sulfate has the advantage of lower cost and higher phosphorus removal rate compared with other flocculant products. The disadvantage is that the flocculation precipitation effect is nearly the same as the effect of polyaluminum chloride, so the premise of choosing aluminum sulfate is that the biochemical requirements are higher, otherwise the floc will be difficult to settle.
5. Machining or cutting fluid wastewater sometimes contains a small amount of oil floating on the water surface of the waste oil, diesel, etc., this wastewater chooses aluminum sulfate, aluminum sulfate can remove the oil on the water surface and play a demulsification role. Aluminum sulfate can also be used as ink wastewater flocculation, oil removal and decolorization. (Note: Only for the removal of oil floating on the surface, oil suspended in water or mixed with water or emulsion can not be removed with aluminum sulfate)
6. Power plant raw water, paper sewage, industrial sewage, etc., can choose polyferric sulfate.
7. Fenton reagent, printing and dyeing, leather, electroplating and other sewage containing heavy metals, chroma, COD high choose ferrous sulfate. The advantage of ferrous sulfate is that the cost is low, and the disadvantage is that the amount of sludge produced is large.
8. Basic aluminum chloride is usually used as ink, leather, printing and dyeing industrial sewage Xuying precipitation, low treatment cost, the disadvantage is that the salt base is high, in the low temperature environment the dosage will become large, suitable for use in the southern region or more constant temperature indoor water treatment process.
9. Pool, well water, reservoir water and other water treatment choose spray drying polyaluminum chloride, spray drying polyaluminum chloride base is low, usually suitable for water with low turbidity.
10. Pure white polyaluminum chloride can mainly be used as papermaking glue, cosmetic additives, food preservatives, etc., in the water treatment industry is relatively few applications, in the water treatment is generally used as reverse osmosis or pure water, mineral water and other water treatment.