Phytoremediation is a process for purifying civil wastewater (kitchen, bathroom), which uses plants as biological filters to reduce the pollutants present in them. Phytoremediation treatments are biological treatments that exploit the self-destruction capacity of aquatic environments, ponds and marshes, where particular types of plants such as canes grow. These plants have the characteristic to favor the growth of microorganisms through which purification takes place.
One of the phytodepuration systems is a waterproof basin filled with gravelly material and vegetated by aquatic plants. At the output only purified water is obtained according to law without any sludge production.
Here, purification takes place through the combined action of gravel substrate, plants, reflux and present microorganisms. Inside the gravel bed, when the wastewater passes, there are microorganisms that activate the biochemical reactions of the degradation of the pollutants. In addition to actively participating in the elimination of pollutants, the plants provide the necessary oxygen to the reactions from the foliar to the root system. For this reason, only plant species with certain characteristics can be used in phyto-purification plants. In particular, the most commonly used species at international level are Phragmites Australis, Carex, Juncus, Typha, Iris.
Phytoremediation plants are biological purification treatments that work through the combined action of bacteria and plants. They need a preliminary depuration, given by an Imhoff pit , which operates a primary sedimentation. From the Imhoff pit in fact, the waste waters come out cleaned of the solid particles, and will be pumped on the sand filter through a pressurized tube system: the water passing through the filter undergoes a purification process carried out predominantly by aerobic microorganisms. The purified waters are conducted in a control well and can be released into surface waterways without creating pollution and eutrophication problems.
The system works in the absence of added energy and therefore of electromechanical parts. This allows you to define the system as “environmentally friendly”.
Properly sized and built, phytoremediation plants help to reduce the organic load of incoming wastewater of more than 90% and in any case compliant with legal limits.
For the sizing of the plants, it is considered to be a daily discharge capacity of 200 liters per day, an amount of BOD5 per capita equal to 60 g / day with a in-let pH between 6 and 8.5.
Phytoremediation plants target the following objectives:
- simplify management and maintenance, minimizing investment and management costs, adopting the least technological intensity and the least possible energy use;
- be able to withstand seasonal variations of hydraulic and organic load;
- to allow the efficient depuration of the smaller and diffused consumers, avoiding the collection of low loads for long distances;
- encourage the use of plant solutions that allow the recovery and reuse of purified waste;
- minimize the landscaping impact and the disturbance conditions of the neighborhood;
- protect groundwater, especially in areas vulnerable to nitrate pollution.
A phytodepuration plant is realized by digging a basin of varying size according to the flow rate and type of drainage. The basin is covered with a waterproofing and functionality system made with PVC cable housing tubes flanges to guarantee sealing.
The basin, once waterproofed, is filled with selected inert material on which the different macrophytic plant types suitable for purification will be planted directly.
The reflux level within the phytodepuration basin is consistently kept 10/15 cm below the surface of the gravel through the installed level control system. The plant can be walked on without surfacing surface water. The total absence of bad smells and insects is guaranteed.