5 February 2024

Complete guide to constructed wetlands: what they are and how they work

Growing environmental awareness has led to a greater focus on sustainable solutions in wastewater treatment. In traditional waste water treatment plants, in fact, an imbalance is generated in the water cycle: water is taken from one water basin and transferred to another. The impact on the environment can therefore be considerable, due to high energy consumption, use of chemicals, and high sludge production.

In this context, phytoremediation has developed as an innovative and ecological wastewater purification system. Designed to artificially reproduce the self-purifying processes present in humid environments, it purifies the waste water coming out of septic tanks or imhoff pits using the action of plants and microorganisms.

Di Camillo Serbatoi, based on its decades of experience in wastewater treatment, sells not only the individual components: the knowledge of our technical staff allows us to create complete and tailor-made systems for all wastewater purification and phytoremediation needs.

What is phytoremediation? Advantages, fundamental principles and operation

Phytoremediation is a completely natural process, which exploits the ability of some aquatic plants such as cattails, reeds and rushes, to remove pollutants from domestic, industrial or agricultural wastewater. These plants, in fact, are able to metabolise the contaminants present in the water, transforming them into nourishment, leaving the process water clean to the point that it can be discharged into a watercourse, sub-irrigation, or directly onto the soil in tab.4.

Phytopurification systems are usually inserted downstream of a primary purification treatment (or pre-treatment), such as a grease trap or an Imhoff tank. It is therefore an incredibly effective solution in isolated living areas that are not connected to the sewer system, but in general phytoremediation is an ecological approach to wastewater treatment. Constructed wetlands, in fact, reduce the environmental impact and require lower operating and maintenance costs, integrating into the environment and improving the landscape.

In a first stage, the contaminated water passes through a bed of permeable soil, which ensures good water circulation. As a guide, the trays for phytoremediation should be filled from the bottom with a layer of vegetable soil, then a layer of non-woven fabric, and 10-20 cm of gravel . The upper layer must instead be composed of pebbles or expanded clay, or 15-20 cm of washed scree.

In this way, the soil acts as a natural filter, retaining solid particles, and facilitating the passage of water through roots and substrate. An ideal environment is therefore generated for the growth of bacteria and microorganisms that contribute to the degradation of harmful organic substances.

The roots of the selected plants, in fact, absorb contaminants suspended in the water, which can include excess nutrients, but also heavy metals and organic compounds. But they also favor air circulation, maintaining aerobic conditions essential for microbial metabolism.

Phytopurification systems: components, device diagram and sizing

For phytopurification systems, Di Camillo Serbatoi manufactures and resells all the key components, from the treatment tanks to the irrigation system. The phytopurification systems are created through a series of waterproof rectangular trays, equipped with 125 mm inlet and outlet pipes, with rubber gasket.

The standard system involves primary sedimentation through an imhoff tank, or septic tank, then a single-walled monobloc polyethylene tank. For the Lazio region, however, the regulations on constructed wetlands provide for double-walled trays. The system is therefore equipped with a series of connecting wells, created to collect the wastewater treated by the plants in the various trays, and proceed with the secondary purification of the sewage or the discharge of surface water.

Constructed wetland plants are sized based on the number of inhabitants, and based on the final discharge of the water, whether it is dispersed, reintroduced to the ground, or in a process, called evapotranspiration, which involves the recirculation of the wastewater. The device layout of the systems remains the same, including (if applicable) grease trap, imhoff, phytopurification tray.

What changes, however, is the number of trays. In the case of soil dispersion discharge, the purification plant must consider 2.5m ² for each equivalent inhabitant, therefore one tray is sufficient for two inhabitants. In the case of dumping on the ground, however, 5 m ² are needed for each inhabitant, doubling the number of trays needed, one per person per inhabitant.

For your wastewater treatment plants and your constructed wetlands, therefore, contact Di Camillo Serbatoi . The more than ten years of experience of Di Camillo Serbatoi’s technicians will help you choose the system tailored to all your purification needs, and will ensure you have the highest quality components tested, and accompanied by all the necessary certifications for your region of residence.