The first rainfall plants are necessary for the purification of water of meteoric origin collected in production yards.
Some companies carry out work processes that create a particular and burdensome pollution.
Rainwater, collected in these situations, is difficult to treat with a system before rain, and it is not possible to guarantee the respect of the tabular limits to the discharge.
In these cases, a plant with a more efficient purification process such as chemical-physical treatment is required.
The chemical-physical plant is used to treat first rain water when the same have a high degree of pollution even with the presence of heavy metals, if this wastewater is treated with a classic first rain plant, a part of these substances are eliminated but it is not sufficient to comply with the table limits in force provided by Legislative Decree 152/2006 for the discharge into the sewer table 3 Annex 5, and must be treated with advanced purification systems.
Water purification before rain with CHF plant
The water from the first rain is collected and stored in a containment basin, and it is then returned to a water purification plant with chemical-physical reactions.
The treatment is as follows:
- Coagulant Dosage, Flocculant Dosage
- pH neutralization adjustment
- Clarification
- Sludge dewatering
- Final filtration
The waters of first rain are added in a special reaction tank of a chemical preparation that performs various functions, this chemical product is able to absorb some pollutants such as oils and hydrocarbons, acts as an agglomerating agent with coagulation effect and flocculates the water to be purified to promote precipitation.
The physical chemical plant has a water neutralization to bring the pH in its optimal condition.
The first rainwater thus neutralized and flocculated is sent to the sedimenter where clarification takes place.
The sludge produced by the purification system is periodically extracted and dried with filter bags and the purified water is sent to the drain.
In some plants there is a quartz and carbon filtration system that carries out a mechanical filtration of the first rain water and an absorption of the last organic substances present.
