The typology produced uses bio-oxidation and chemical-physical processes. The first typology is adapted for drainages of mechanical workshops, service stations, car washes and other similar companies, and uses MBBR technology prescribing at first a pretreatment of sand separation and oil separation, and subsequently a biological treatment of prolonged aeration on a mobile bed (bio-purifiers).

With the bio-oxidation process, the systems for auto washes become entirely processed with the employment of monoblock reservoirs prefabricated in concrete. The treatment results in having the maximum effectiveness in this case by utilizing detergents and similar products to an elevated tenor of biodegradability.

In case products of low biodegradability become utilized during the washing operations, the analysis of drainage waters becomes necessary so that with opportune planning, the chemical-physical system becomes optimally customized for the requirements of the customer.

The chemical-physical systems, adapted for drainages of greater consistency and with polluting contributions of a more varied nature, which derive from chemical, petrochemical, galvanic, pharmaceutical, and ceramic industries and from cement works, quarries, dry cleaners, glass factories, furniture factories, etc…, are instead realized in 2 versions:

1. with processing on a monoblock skid to an elevated compactness, complete with reaction and sedimentation reservoirs, equipped with all the necessary plant engineering for the appropriate function, all processed in carbon steel painted with a polyurethane cycle or in steel INOX AISI 304. The monoblock skid is positioned out of ground.
    

2. with various monoblock prefabricated concrete reservoirs of rectangular section, that are also variously equipped.

In the typical installation, such products become buried to the level of the drainage duct and elevated up to the ground level through elevation structures and elements of pedestrian or carriageable cover. Therefore, in the area containing sewage water, the reservoirs do not introduce joints or other elements of discontinuity and therefore offer the maximum guarantee of hydraulic seal beyond that of structural stability and resistance over time to the corrosive action of the sewage waters.

In the project design of the chemical-physical purifiers it is good practice to conduct coagulation-flocculation tests in the laboratory on a sample of the sewage water to be treated, in order to choose the most adequate chemical additives and to estimate the dosages. Such tests can be executed from our technical office contextually with the plan calculations elaborated on the basis of the results obtained and of the ulterior data supplied by the Customer.

The outcomes of the tests and the calculations, with the relative graphical elaborations, are documented in a technical report that can be used integrally for the request for authorization for drainage.

The chemical-physical purification is the technique that is normally used for the de-pollution of non biodegradable industrial sewage waters. Such technique allows for removal of the contaminating substances of suspended and colloidal nature from sewage waters, through a procedure articulated in two successive phases:

• in the first phase (coagulation-flocculation) the sewage water comes mixed with chemical additives (typically a primary coagulant, a pH corrector and an auxiliary coagulant) that provoke the agglomeration of the polluting agents in ribbons;
   

• in the second phase (clarification) the ribbons become separated and removed as sludge while the purified water gets sent on for final drainage or recovered in an appropriate accumulation tank.

PRE-TREATMENT

The water coming from the washing pit meets in the first reservoir where it endures a slowing down by means of a localized deflector septum at the entrance, where it lingers for the time necessary to allow for settling of sedimentary materials, that is sands and dirt. The light liquids, oils and gas, by difference of specific weight, tend to float to the surface. The basin is equipped with a coalescence filter to stopper the drainage, which is sized in relation to the maximum influx capacity.

The drainage becomes closed automatically by a floater stopper, in order to prevent the spillage of the oil when this last one arrives to a determined level.

TREATMENT

After having been pretreated, the sewage reaches the biological reactor DEPURA MUSILLI, conceived with utilization of MBBR technology.

The incoming water crosses the bioreactor from above and moves towards the bottom, aerated in a counter-current with special air feeding diffusers from an electric blower with lateral channels. Based on the influx capacity, the biological reactor introduces suitable bits of plastic filling material. The bits of plastic float as a result of the air in the counter-current, to which the entire liquid mass is subjected.

On such bits of plastic filling material floating in the bioreactor, bacterial colonies take root which are deployed for the biodegradation of the surfactants; the capability of maintaining concentrations of elevated biomass in the tank, and the biodegradation of the organic substances, united with the phenomena of adsorption and floatation, comprise one complete purification of waste water without the employment of additional chemical substances.

The escape of air from the bottom determines the formation of microbubbles that ascend transporting the exceeding biomass that it is detached periodically from the floating plastic supports.

The oxygen presence avoids the awakening of anaerobic conditions and consequently formation of bad odors.

The attainable advantages with utilization of the DEPURA MUSILLI system are essentially two:

• the first is due to the purification system that provides remarkable energy savings in comparison to the traditional system with active sludge (simple conduction, resistance to overloads and limited blocks)
   

• the other derives from the employment of MBBR technology with the use of loose bits of plastic filler material, that act together to obtain elevated surface specifications, with good purification performance even in the presence of high organic fractions, and when resorting to simple and less expensive civil works, with respect to the traditional systems in gravel or the like.

A secondary sedimentation basin without sludge recirculation is all that is needed ahead of the bioreactor to produce waste that complies with current legal discharge requirements.

In case one opts to re-use the sewage, the effluent from the secondary sedimentation becomes fed to a treatment of final filtration on quartziferous sand and active carbons. The dimensioning of bioreactors DEPURA MUSILLI is realized with consideration for the maximum affluent capacity into the system, that is obtained from the product of the maximum hourly number of washings times the water consumption.