First Rain Water Reuse

Five, ten seconds to make a criticality an asset

Rainwater, which falls in industrial and civil plant yards, can be treated by removal of its oil and grease component and reused. Several solutions from MITA Water Technologies can support in this purpose: Oilpack oil separators, Flowpack decanters, Mitadaf flotation units.

Rainwater reuse: need and regulatory framework

First rainwater is stormwater that, falling on the ground for the first time, has not had a chance to come into contact with soil or impermeable surfaces.

They are generally good quality water and can be reused for a variety of purposes: irrigation, street cleaning or powering plants. This is under one condition: only water that fell in the first 5-10 seconds of a rain event can be reused. The reuse of first rainwater is thus a practice that is becoming increasingly important, both for environmental sustainability and for the economy:

  • Environmental sustainability: first rainwater reuse can help reduce surface and groundwater pollution by reducing the pollutant load from stormwater.
  • Economics: reuse of first rainwater can help reduce water supply and management costs, particularly in times of drought.

The regulatory framework established by the European Union for this practice includes Directive 2000/60/EC (Water Framework Directive), which establishes the contribution of member states to the reuse of treated wastewater. In contrast, Directive 91/271/EEC (Urban Waste Water Directive) establishes minimum requirements for urban water treatment.

Tell us your needs
Riutilizzo Acque Prima Pioggia

Useful processes for the reuse of stormwater

There are two main steps for the reuse of first rainwater.

  • Collection of first rainwater: this can be done through different systems, such as catch basins, collection channels, and gutters.
  • First rainwater treatment: depuration can leverage different types of purification, depending on the quality and quantity of the effluent to be treated.

It is important to note that the choice of the most appropriate collection and treatment processes must be made with a number of factors in mind.

  • Amount of stormwater to be collected. This determines the sizing and capacity of the collection system.
  • Quality of first rainwater. As with all other types of wastewater, treatment systems are determined by a number of parameters: total suspended solids, BOD/COD values, oils and fats present, phosphorus, nitrogen.
  • Specific reuse needs: specific reuse needs, such as water destination, determine the most appropriate process and technology.

That said, some examples of useful processes for the collection and reuse of stormwater include: de-oiling, settling, liquid chemistry, phytodepuration, and final filtration.

MITA Water Technologies' solutions for stormwater treatment

We have numerous references to our credit in the treatment of first rainwater, including for reuse: as in other circumstances, MITA Water Technologies’ solutions cover different stages of treatment and can be installed, depending on the circumstances, either independently or as a complement to other technologies or solutions (such as chemicals).

Some examples of technologies and applications?

  • Oilpack lamella-pack oil separators. Due to the continuous increase in atmospheric pollution, runoff water from roofs and yards is loaded with pollutants, particulate matter, oils, etc.: for these needs the Oilpack oil pack oil separator comes into play, particularly as a pre-treatment of this water with respect to subsequent mechanical or biological interventions and, of course, downstream of appropriately sized storage tanks. It is a system that does not require continuous operation and is therefore excellent in occasional events such as storm events.
  • Flowpack lamella-pack decanters. This solution operates stormwater treatment: MITA Water Technologies has case studies with Flowpack to its credit, especially in integration of a chemical-physical treatment cycle consisting of coagulation, flocculation, and settling.
  • Mitadaf dissolved air flotation units. A typical case in which our company has proposed this simple and efficient technology is the oil industries: oil depots and refineries are large establishments, and the associated rainwater and runoff falling on yards and buildings must necessarily be treated before discharge, also considering their high oil load. Some considerable advantages of Mitadaf’s floaters, especially in these plants: removal efficiency, small footprint, and the ability to fit the machine into the context of an existing plant. In addition, Mitadaf makes it possible to increase the efficiency of pre-existing biological treatment plants.
Ask for Information

Some MITA Projects

Water Treatment and Cooling Systems for Vedani Group

Various industrial water treatment technologies as well as cooling technologies: since 1995 MITA Water Technologies has provided multiple solutions, together with its "sister" company MITA Cooling Technologies, for the complete water management of Vedani Group, which has been active in aluminum processing since 1982.

Read more

Tools to help you choose


Industrial and civil wastewater treatment technologies

Simplicity, reliability ... and the lowest product life cycle cost: water treatment solutions from MITA Water Technologies.

Our support throughout the product life cycle

We offer a series of additional support services for our customers: the MITA Lifecycle Services.
Idea icon

A sustainable and efficient solution for every industry and need

Wastewater treatment will increasingly be a resource efficiency and optimization opportunity for organizations in both civil and industrial settings.