Use and specifications
1. GRIT SEPARATOR: this is where all the compounds of specific weight different to that of water are separated by gravity: the heavier materials (sand, mud, gravel,…) settle to the bottom of the tank while the lighter materials (oil, grease, foam,…) accumulate at the surface. The outlet pipe draws from halfway down the tank to prevent the separated material from being drawn-off.
2. OIL SEPARATION TREATMENT: the residual oils and hydrocarbons are trapped by the coalescing filters, thus separating them from the effluent.
3. INTENSIVE BIOLOGICAL TREATMENT: in which particular strains of bacteria digest the dissolved organic substances (BOD5 and COD) and the detergents (Phosphorous). The biological treatment consists of an aerated trickle filter.
4. TERTIARY TREATMENT: to improve the quality of the treated water to discharge it into the open air/to the land or to re-use it in the initial phases of the washing cycle (pre-wash,…), the treatment plant is combined with a tertiary treatment consisting of a quartzite and activated charcoal filter system fed by a lift station.
TECHNICAL CHARACTERISTICS
The growing interest for environmental protection and safety is focussing more and more not only on treatment of domestic sewage or the like but also, particularly in recent years, on treatment systems for runoff from potentially polluted impermeable surfaces. This includes water from car washes, which is characterised by the presence of various types of pollutants such as: suspended solids (sand and mud, gravel, grit, plant residue,…), detergents, mineral oils and hydrocarbons. For this reason, the purification treatment of these effluents requires a series of phases that treat the pollutants in succession.
Choice of the different types of treatment varies according to the final discharge (to public sewer, to surface watercourse, to land or re-use).
The first phase consists of a grit separator in which all the compounds of specific weight different to that of water are separated by gravity: the heavier materials (sand, mud, gravel,…) settle to the bottom of the tank while the lighter materials (oil, grease, foam,…) accumulate at the surface. The outlet pipe draws from halfway down the tank to prevent the separated material from being drawn-off.
The second phase is the oil separation. The residual oils and hydrocarbons are trapped by the coalescing filters, thus separating them from the effluent. In the third phase, the effluent is subjected to intensive biological treatment, in which the particular strains of bacteria digest the dissolved organic substances (BOD5 and COD) and the detergents (Phosphorous).
When discharging to a public sewer, the biological treatment consists of an aerated trickle filter. When discharging to a surface watercourse, another anaerobic trickle filter is added upstream. The blowers of the aerated trickle filters must remain in operation 24 hours a day.
Finally, to improve the quality of the treated water to discharge it into the open air/to the land or to re-use it in the initial phases of the washing cycle (pre-wash,…), the treatment plant is combined with a tertiary treatment consisting of a quartzite and activated charcoal filter system.
USE: treatment of water from manual and automatic car wash areas
REFERENCE REGULATIONS: Law Decree 152/2006, standard UNI EN 858-1 (oil separator), regional standards for treatment of rainwater and runoff.
INSTALLATION DIAGRAM
QUARTZITE AND ACTIVATED CHARCOAL FILTRATION
DESCRIPTION OF THE PLANT
One-piece filtration plants are the most rational and economic means of treating effluent characterised by pollution due to the presence of substances such as Suspended Solids, Hydrocarbons and Surfactants from: car washes, mechanical workshops, etc.. Their economy of operation relates to their ability to work without the need for operator intervention, which is only required for a few minutes/week, during the periodic wash-out operations. The systems do not require chemical products for operation, so the salt content of the waste water is not altered. This is particularly advantageous in all cases when partial re-use of the treated water is required.
The filtration lines consist of two tanks or columns, equipped with No. 2 inspection covers, to allow periodic operations to load and replace the Quartzite and/or Activated Charcoal filter beds. These are extremely reliable and long-lasting finished products, that are able to withstand both the action of chemical agents and the weather. All the electromechanical equipment installed to support the plant feature maximum reliability, extreme simplicity of use and a minimum need for maintenance.
TREATMENT CYCLE FOR DISCHARGE TO LAND OR RE-USE
- The water to be treated following external car washing activities is carried to the pre-treatment section, which consists of grit separator, coalescing filter type oil separator and aerated trickle filter.
- The waste water leaving the pre-treatment section enters a so-called homogenisation and storage tank, which contains the submerged electric pump used to power the plant.
- The pre-treated water is then sent to the first stage of filtration, where it passes through a bed of ultra-fine Quartzite, with a suspended substance selection level of around 50μm.
- After this, the clarified waste water moves on to the second stage of filtration, consisting of an Activated Charcoal bed. The feature of activated charcoal is its ability to retain, within its microporous structure, pollutants such as, for example, Surfactants, Hydrocarbons, Solvents etc.
