1 August 2024

Wastewater purification: stages and treatment components (part 2)

The primary treatment of wastewater already guarantees good purification results. For some uses of purified water, however, such as recycling for agricultural use and dispersion on soil, further secondary treatments are envisaged, which improve the quality of the effluent, and further reduce the organic load and polluting substances present in dispersion, making the discharge safer for the environment, and compliant with the most stringent environmental regulations.

Secondary treatment

However, wastewater that has completed the first stage of treatment may undergo secondary treatment before final delivery, to refine the quality of the effluent, or in response to specific environmental regulations, which may be more stringent in some regions or situations.

Trickling filters

Trickling filters are both anaerobic and aerobic biological reactors which, thanks to the particular filling material that allows certain species of bacteria to take root, further improve the quality of domestic wastewater by treating organic residues. The water treated through an anaerobic percolating filter can therefore be delivered to the sewer, but also to sub-irrigation or watercourse (after primary treatment). Aerobic trickling filters, on the other hand, also allow discharge to the ground.

 

Activated sludge plants

Activated sludge systems use the same principle as trickling filters, using aerobic bacteria to digest organic matter. In fact, inside them there is a diffuser that guarantees their proliferation, for a purification efficiency of 90%. Associated with a primary treatment such as an imhoff pit and a grease trap, the water treated by an activated sludge plant can thus be discharged into sub irrigation, onto soil, or sent to subsequent treatment phases.

 

Monobloc activated sludge purifiers

Monobloc activated sludge purifiers combine three treatment zones: sedimentation, oxidation and settling. In these compartments, bacterial colonies feed on biodegradable organic material, and produce oxygen bubbles that allow correct mixing of the flow. The monobloc purifiers can be used either as secondary treatments, or, associated with an initial degreasing phase, they can be used for the primary treatment of domestic wastewater, with discharge into underground dispersion or into surface watercourses.

Secondary treatment for waste water

Secondary treatment plants for discharge onto the ground, composed of an anaerobic percolator and an activated sludge plant, are a secondary treatment that allows the recycling of water for irrigation use or direct discharge onto the ground (if associated with a primary treatment such as a tank imhoff or grease trap). The water is introduced into a series of tanks, where it first undergoes anaerobic purification, and then aerobic purification. In fact, in the second tank, the micro-bubble diffusers powered by a membrane compressor introduce air bubbles which activate the digestion of organic substances. A final section of the tank, the clarification area, separates the suspended sludge before leaving the plant.

 

Final step

Wells (for tax collection and dispersants)

Eventually, properly treated wastewater can be dispersed to the surface. This always occurs by monitoring the water through mandatory sampling carried out through the tax collection wells, in compliance with current regulations. Dispersant wells are the last component of a wastewater purification system and, when necessary, disperse the wastewater into the surface layers of the ground.

For your wastewater treatment systems (including first rain or car washes), rely on Di Camillo’s experience: for over sixty years we have been offering our customers professional solutions and complete systems, as well as components tailored to all needs of purification.