When for economic reasons or for special geographical situations we must abandon the creation of a centralized system, the use of small plants for wastewater treatment for civil use is required.
For the biological treatment of effluent from medium-small residential areas, an ideal process cycle consists of screening, a primary settling tank with a sludge digestion tank (Imhoff tank), a biological purification treatment and the separation of excess sludge.
In the compact biocombi plants with the filtration system offered by MITA Water Technologies, the biological treatment occurs through a partially immersed disc (biodisc) on which the biomass forms. In lieu of the final sedimentation tank, the use of a cloth filter is provided which consists of a horizontal perforated metal sheet drum coated with a special filtration cloth equipped with the proper system for the removal of separated sludge.
The most obvious advantages of the system are the minimal energy consumption, maintenance limited to a few simple operations, the small size, the steady performance with regards to variable loads and not least, the absence of noise and unpleasant fumes.
The biological purification phase occurs with a biodisc made of polypropylene parallel discs mounted on a central axis, the diameter of which varies according to the plant size, in a range between 2.00 m to 2.40 m. Forty percent of the surface of the discs is immersed in wastewater and it’s well suited for the growth of bacterial flora, the main architect of the biological purification treatment.
The cloth filter replaces the secondary sedimentation tank. The biologically purified water can reach the discharge only by passing through the filter cloth, the surface of which little by little is covered by a layer of sludge which causes the increase in the pressure drops. A level sensor actuates a pump that, through a vacuum unit in contact with the cloth, collects the water necessary from inside the drum to clean the cloth. The sludge removed is released in the primary settling tank, if any, or to another destination (sludge treatment).
Other than the compliance with the legal requirements, the purification system effectively responds to important practical requirements. The maintenance is greatly reduced compared to conventional plants which can be performed by unskilled personnel.
The MITA Biorulli compact plants in the BC series are particularly ideal for small towns or villages, tourist resorts and hotels.

Compact system for the biological purification treatment with biodiscs combined with cloth filter for the separation of excess sludge.
The biocombi compact system features two treatment phases (biological treatment and separation of excess sludge) gathered in a single tank.
The standard model provides the complete provision of a carbon steel tank treated and painted with a fiberglass modular cover easily removable, and an electrical switchboard on the machine with IP 55 protection.
The moving parts (disc roller and drum filter) are actuated by a single geared motor with power included between 0,75 and 1,10 kW.

Compact system for the biological purification treatment with biodiscs combined with cloth filter for the separation of excess sludge.
The biocombi compact system features two treatment phases (biological treatment and separation of excess sludge) gathered in a single tank.
The standard model provides the complete provision of a carbon steel tank treated and painted with a fiberglass modular cover easily removable, and an electrical switchboard on the machine with IP 55 protection.
The moving parts (disc roller and drum filter) are actuated by a single geared motor with power included between 1,10 and 1,50 kW.

System advantages

• Minimum energy consumption
• Reduced maintenance
• Easy accessibility
• Increased floor space (compact construction)
• Reduced sensitivity to sudden changes in hydraulic and/or organic load
• High operating safety
• Unlimited oxygen supply for aeration or diffusion
• Low installation costs
• No odor nuisance or aerosol
• Pre-assembled systems ready to start, complete with electrical switchboard on the machine which consent very fast installation and startup

Application fields

• Small communities: the optimum population range for the use of biocombi plants in municipal discharges is included between 50 and 1.500 population equivalent. In communities with high seasonal population fluctuations, energy and personnel shortages, the possibility of future up-grades and the proximity of the population center, etc., this compact system offers obvious advantages over other alternative systems for biological purification treatments: extraordinary capacity to adapt to fluctuations, both in terms of the flow rate and composition of the sewage to be treated. In particular compared to a load markedly below full capacity, the system reacts spontaneously without undergoing any setbacks unlike what can happen with activated sludge technology plants; low-power installed and low energy consumption; low maintenance and management costs; possibility of plant growth with regard to the served population growth; low noise and absence of aerosols; high purification rate.
• Tourist villages and camping: for this type of discharge, the plant is operational only a few months each year with a peak season from June to August and off-peak from August to September. The only biological purification system with a maximum capacity size that can operate in any condition and with no corrective interventions is certainly the biodisc system. When associated with a section of the cloth filters, our biocombi compact plant guarantees a complete purification process in reduced dimensions in terms of space and high purification efficiency. Besides this, it is also important to have a process that is triggered as soon as possible with the flow of the first users or the service staff before the opening.
• Sites: these waters are ascribable by their features to the discharges from small communities. The biocombi plants are used in a range of fields especially in light of the fact that they are monobloc with reduced dimensions and therefore allow for easy mobility and a quick start-up. You can move the plant several times where necessary to carry out the treatment of waste water. At the same time the performances are absolutely comparable to a complete wastewater treatment plant. In this sector, the combination of biorulli^® and cloth filters offers the unmistakable advantage of an easy adaptation to different types of discharges in terms of quality and quantity. Among the advantages of the biocombi plants, the minimum floor space and easy operation even by unskilled personnel should be mentioned.
• Hotels: because of their compactness, the biocombi and biorulli^® plants can be installed in hotels that have either seasonal or annual activities. The features of biocombi address the sector’s needs with high efficiency. It is always advisable to have flexible systems for each load condition, either hydraulic or biological, with the least possible use of maintenance and management manpower. Compared to other biological purification alternatives, the proposed system is less noisy; it has a better environmental impact because of its compactness and the possibility of placing it inside a structure. The cloth filters instead of a secondary sedimentation guarantees excellent results in terms of quality of wastewater, thus ensuring compliance with the limits of the law.
• Schools: the treatment with the compact biocombi plants is offered in this context because of its easy management and control in situations where there is a lack of personnel as well as not being qualified. The flow must obviously be equalized as the waters are discharged only a few hours each day. Unlike other biological processes, the compact biocombi plants tolerate long periods of inactivity (weekends, summer holidays, etc..). On completion of the plant, scheduling an effective pre-treatment (primary sedimentation, fine screening or similar systems) upstream from the equipment is sufficient.
• Highway service areas: this is one of the applications for which over the years MITA Water Technologies carried out the largest number of machine installations. One of the most important features of the biological disc systems is in fact the extraordinary capacity of the system to adapt to fluctuations, either in terms of the flow rate or the composition of the sewage to be treated that often are very abundant in the discharges from service areas. In particular, compared to loads below full capacity, the system reacts spontaneously without undergoing any setbacks. In contrast with the systems previously designed and manufactured to use the activated sludge technology, the lack of organic matter that occurs in relation to loads below full capacity has caused the blocking of the process. An additional advantage offered by biocombi compact system consists of the little maintenance and control required by the management staff of the area service. Finally, the compactness of the plant, its scalability and the cloth filtration instead of the traditional settling make it ideal for this type of system.