We offer the best option available to meet your needs, without any business-related constraints, by selecting the most suitable solution for you among all existing technologies.
CID srl has been managing more than 250, among new and old, wastewater treatment plants, of every kind and dimension: this unique overview on the evolution of purifying techniques empowered us with the knowledge of the respective strengths and weaknesses in order to offer the best option available.
The treatment of wastewater by means of the activated-sludge technology is performed by specific bacterial species.
Thank to the oxygen coming from the outside, said bacteria activate and reproduce by feeding themselves of the organic matter present in the wastewater. Afterwards, they aggregate in colonies (called biomass or sludge flakes) whose specific weight is greater than water.
The settling phase follows (solid-liquid separation). It occurs within a specially designed tank, called grit chamber, where the heavier part (biomass) settle, while surface clarified water is collected and reach the discharge system.
On the contrary, the part settled in the grit chamber (biomass) is gather and recycled in the first phase of the process.
Since the biomass feeds on and reproduces by means of the pollutant that reaches the plant, it will constantly increase in terms of concentration. Therefore, periodically, the excess part is extracted and expelled from the process (disposal or reuse).
The SBR (Sequencing Batch Reactor) purifying treatment technology is an application of the traditional activated-sludge treatment plants, where all different phases (denitrification, oxidation, nitrification, settling and discharge) occur sequentially, but within the same compartment.
Once the supply/oxidation/nitrification phases are completed, if need be alternatively with some controlled denitrification phases, the aeration plant is stopped, so that the sludge can settle (settling phase).
After a pre-established timeframe, the supernatant clarified water (purified waters) is extracted, by means of electric pumps or by gravity, and taken to discharge or, if need be, to further finishing treatment phases.
This system has some technical advantages, beyond the simplification of the plant connected to the use of one single tank for the aeration and settling phases, there is the possibility to equalise the influential sludge and to avoid the formation of slurry crusts on the surface (since they are constantly removed by the reactivation of the aeration phase).
In view of that, the system finds favourable applications in treating industrial wastewater, which are characterised by discontinuous loads from a qualitative and quantitative point of view, or in the purifying plants serving small communities, in the prefabricated version.
It might be applied to civil wastewater treatment plants, where, considering the continuous hydraulic load, they usually install a double line for an alternate functioning.
The MBR (Membrane Bio Reactor) wastewater treatment plants are traditional activated-sludge purifying plants, where the finishing clarification (separation biomass/water) does not occur by means of settling, but filtration through specific microporous membranes.
The membrane modules are characterized by a hundreds of micron filtering efficiency, and are equipped with an air cleaning system to avoid its blocking, which grants the membrane a long life cycle.
The purifying performance is extremely high, since it is possible to operate with an elevated concentration of biomass and the clarification of wastewater is ensured by the process of filtration.
Here are the advantages with respect to the traditional activated-sludge solutions:
The MBBR (Moving Bed Bio Reactor) wastewater treatment plants are an application of the biofilm treatment plants, which are biological plants where the biomass in charge of operating the degradation of the polluting load present in the wastewater is not floating in the liquid mass, but adheres to special plastic supports that can move freely within the reactor.
The biomass grows and develops on these supports, from which spontaneously detaches when exceeding, flowing along with the hydraulic flow in the finishing grit chamber, where it settles. The surface purified waters proceed to discharge and the settled biomass coming from the grit chamber exits the purifying cycle for thickening/disposal.
Here are the advantages with respect to the traditional technologies:
As a consequence of the increasing request of wastewater treatment plants in isolated communities, or villages where no public sewage is available, we enlarged our activity comprising the production of prefabricated wastewater treatment plants. However, they are characterised by the highest quality standards and cutting-edge treatment technologies with the aim of providing efficient, reliable and easy to maintain solutions, which offer, if need be, the possibility to recover/reuse the treated water.
Different purifying technologies may be used for this kind of realisations, depending on the application context and objectives to reach. Mainly, the membrane technology (MBR) and moving bed reactors shall apply in consideration of their efficiency against of the volumes occupied.
For plants servicing smaller communities (population equivalent up to 40) we usually use the SBR technology too, for its simple construction and the consequent excellent cost-performance results.
Considering the final destination and infrastructures available, we can use different construction technologies: concrete prefabricated tanks, steel tanks, circular tanks equipped with panels in glazed steel or stainless steel, even polyethylene tanks (HDPE) for smaller plants. The objective is to reduce, and even avoid, civil structure to realise on site and, therefore, the commitment by the client.
When the wastewater cannot be purified biologically, we inevitably opt for chemical-physical treatments and by adding external agents (chemicals, gas) in combination with mechanic procedures, we succeed in eliminating or oxidising pollutants.
There are many wastewater treatment technologies we can apply in this field (clari-flocculation plants, dissolved air flotation, chemical oxidation, etc...), however, we can design and realise plants to treat every kind of industrial wastewater chemically, following the same guidelines:
We put particular emphasis on the control and automation side, which we plan carefully in our offices on the base of the operating feedbacks from our technicians, with a view to offering a functional, reliable and user-friendly product.
When we are up to treat industrial wastewater with an elevated load of COD and a good biodegradability, which would require very big tanks and notable operating costs by adopting an activated-sludge aerobic treatment, it is worth to pre-treat incoming wastewater in an anaerobic digestion phase.
Therefore, by adding almost zero energy, the organic load is reduced by 80-95 % and converted into biogas. At a later stage, in case the required discharge limits required a further treatment, the wastewater coming from the anaerobic phase could be further treated in a consecutive aerobic stage.
The advantages of this combined solution, anaerobic + aerobic, are remarkable:
The anaerobic digestion, in particular for industrial water, where the use of high-rate reactors is recommended because of the important organic and hydraulic load of the influents (conversely they would need extremely big reactors), is a delicate process that shall meet different biological and functional balances to be successful. Therefore, when we are up to the choice of the applicable technology, we rejected the most complex ones (UASB, fluid bed...) and opted for simple and stable solutions, as the down-flow anaerobic moving bed biofilm reactor:
Following our experience, this system is the one that is least affected by load variations, hence granting a better stability.
For clarifying and disinfecting primary waters to be reused in civil and industrial facilities or destined to human consumption (potabilisation), we use the membrane ultrafiltration technology in combination with other traditional chemical treatments, if needed (activated carbon, demineralisation...).
The system works thanks to the filtration through hollow fibre microporous membranes installed in dedicated and completely automated skids.
With respect to traditional systems, which include multiple steps, such as coagulation, flocculation and settling, beyond the dosing of disinfectants to remove the bacterial load, using membranes allow to purify and get pure water, from a bacteriological point of view, in one stage only and with no use of chemicals.
Therefore, against reduced energy costs (0.3/0.5 KW/m3), maintenance costs (membranes last over many years), and operating costs (no batching of reagents), we can guarantee an excellent purifying result (turb. < 0.1 NTU, bacterial removal > 4 Log) and, mainly, a reliable outcome. The modular system allows, by adding a few modules, to adapt to different needs in terms of performance.
