Jul, 21 - 2014   technology

SFC Environmental Technologies Private limited

SFC is a global water and wastewater group of companies. It has offices and companies in India, Austria, Poland, Vietnam, Czech Republic, Egypt and China and a worldwide sales representative network.The Indian Operation of SFC Group, SFC Environmental Technologies Private Limited commenced in the year 2005 and has competent and well experienced team of professionals to handle large projects for water and wastewater treatment for industries, towns and cities.SFC is a technology company and specializes in providing design, engineering and technology for Cyclic Activated Sludge Technology (C Tech), an advanced sequential batch reactor process. This technology is extensively used for treating domestic sewage and industrial effluents. A very high degree of treatment of waste water is achieved which makes it suitable for recycle and reuse at a very low cost of treatment and by using minimum space.The treated sewage from C Tech plants can be recycled for industrial applications, gardening, agriculture and other applications. There are numerous plants installed and working world wide.

The C-Tech Process

C-Tech is a CYCLIC ACTIVATED SLUDGE TREATMENT process. It provides highest treatment efficiency possible in a single step biological process.

The C-TECH – System is operated in a batch reactor mode this eliminates all the inefficiencies of the continuous processes. A batch reactor is a perfect reactor, which ensures 100% treatment. Two or more modules are provided to ensure continuous treatment. The complete process takes place in a single reactor, within which all biological treatment steps take place sequentially.

No additional settling unit, secondary clarifier is required!

The complete biological operation is divided into cycles. Each cycle is of 3 – 5 hrs duration, during which all treatment steps take place.

Explanation of cyclic operation:
A basic cycle comprises:
• Fill-Aeration (F/A)
• Settlement  (S)
• Decanting   (D)

These phases in a sequence constitute a cycle, which is then repeated.

A Typical Cycle
During the period of a cycle, the liquid is filled in the C Tech Basin up to a set operating water level. Aeration Blowers are started for a pre-determined time to aerate the effluent along with e biomass. After the aeration cycle, the biomass settles under perfect settling conditions. Once Settled the supernatant is removed from the top using a DECANTER. Solids are wasted from the tanks during the decanting phase.

These phases in a sequence constitute a cycle, which is then repeated.

C-Tech Components
The C Tech system comprises the following features,

1. Biological Selector zone

2. Oxygen Uptake rate control “OUR”

3. Co Current Nitrification and De nitrification, Phosphorous removal

4. Complete Decanter assembly in Stainless steel

5. Diffusers, Blowers and Aeration grid

6. Submersible pumps for return sludge (RAS) recycle and Surplus sludge (SAS) pumps for sludge wasting

7. PLC unit for complete automatic cycle control and operation

Decanter Assembly in Stainless Steel

The clean supernatant is removed from the basin using a Decanter assembly complete in stainless steel construction. During decanting there is no inflow to the basin. The moving weir DECANTER is motor driven and travels slowly from its “park” position to a designated bottom water level. Once the Decanting phase sets in, the decanter automatically lowers to the required bottom level. Variable frequency drives are provided to control the rate of movement of the Decanters. After the required level of supernatant is removed the Decanter is returned to its “park” position through reversal of the drive. The basin is now ready for the next cycle to begin.

Biological SELECTOR Zone

The incorporation of a biological SELECTOR in the front end of the C-TECH- Systems distinguishes it from all other technologies.

The raw effluent enters the SELECTOR zone, where ANOXIC to ANAEROBIC -MIX conditions are maintained.

Part of the treated effluent along with return sludge from the aeration basin is recycled in here, using RAS pumps. As the microorganisms meet high BOD, low DO condition in the SELECTOR, natural selection of predominantly floc-forming microorganisms takes place. This is very effective in containing all of the known low F/M bulking microorganisms, eliminates problems of bulking and sludge foaming. The special method of operation referred to above has been proven effective in the containment of Nocardia and Microthrix Parvicella which often are the cause of nuisance surface foaming.

This process ensures excellent settling characteristics of the bio sludge. SVI of treated effluent of less than 120 is achieved in all seasons.

Also due to the anoxic conditions in the SELECTOR zone, De nitrification of the recycled Nitrified effluent occurs. The biological SELECTOR also assists with the selection of poly P microorganisms. Using 4 hr cycles and re circulating activated sludge to this zone, exposes the biomass to appropriate reaction conditions. This favours the selection of phosphate accumulating microorganisms.

The figure below shows the experience with SVI developments in parallel operations with a wastewater that traditionally favours sludge.

2. Oxygen Uptake Rate (OUR) Control
The C Tech process uses measurement of dissolved oxygen (DO) levels in the basin to provide a full-scale control of the activity level in the aeration basin. The DO concentration profile is automatically ramped to operate at slightly higher DO concentrations at the end of the cycle. This feature prevents low dissolved oxygen type filaments from proliferating.

Once DO level is measured in the basins, the rate of drop in DO level is calibrated to know the actual oxygen uptake rate (OUR) of the biomass. In this way, the metabolic activity of the biomass is measured within the actual process basin and is subsequently used as a control parameter to automatically regulate the duration of the aeration sequence and/ or the rate of aeration. Aeration Cycle time can be altered automatically, or else a variable frequency drive automatically alters the aeration blower rpm. This methodology provides a true in-basin method for the efficient use of energy.

3. Co current Nitrification and Denitrification

C-Tech process allows co-current Nitrification and Denitrifaction (N/DN) to occurr in the same basin simultaneouly.

Biological Reactions

1. Biodegradation (aerobic)
Organics (BOD) + O2 + Nutrients + Bacteria = New Bacteria + C02 + H20

2. Nitrification (aerobic)
NH3-N + O2 + Nitrosomonas = NO2 + O2 + Nitrobacter = NO3

3. De nitrification (anoxic)
NO3 + organic substrate + Heterotrophic = N2 + CO2 + H2O + New cells

4. Phosphorous removal (anoxic/anaerobic/aerobic)
VFA (organics) + Acinetobactor = release O-P
O-P + Bacteria + O2= new cells + cell maintenance

Co Nitrification/ Denitrification
In the Ctech basin, excess oxygen is provided to oxidise ammonical nitrogen into nitrates. This is an aerobic process. The biological process is regulated in such a way that the biofloc profile allows for nitrification at the peripheral sections and denitrification at the inner parts of the flocs.

Ammonical nitrogen (NH4-N) is converted into nitrates (NO3-N) during the aeration process. Aeration is then stopped to allow for settling of the biomass. During this time, anoxic conditions set in which allow for denitrifnication of the nitrates (NO3N) into nitrogen (N2) and carbon di oxide (CO2) gas. Also at the start of each cycle, part of the settled biomass is recycled into the selector zone using the RAS pumps, where in raw effluent is also fed.

The raw effluent acts as a substrate for the denitrification bacteria and under the influence of, anoxic conditions denitrification occurs. Elemental oxygen is released during this phase. This process of co Nitrification and Denitrifictaion result in complete removal of Nitrogen from the effluent.

Phosphorous (P) Removal
The key to Phosphorous removal is exposure of microorganisms to alternating aerobic and anaerobic conditions. The alternating condition stresses the microorganism to uptake higher concentration of dissolved phosphorous, from the effluent thereby reducing the Phosphorous level in the effluent. Phosphorous is used by the microorganism for cell maintenance, synthesis, energy transport and is also stored for future requirements.Operational Simplicity – Fully PLC based intelligent control
The complete CTech plant operation is controlled automatically thro a PLC system, which is a major factor in reducing operating costs. This also prevents mal operation of the various set process parameters within the plant.All key functions like, RAS, sludge wasting, aeration intensity, cycle time control, decanting rate etc are automatically controlled as well as data logged.

Complete historical records of plant operation are available on touch of a button. Using suitable modem, these plants can be monitored and controlled thro Internet from anywhere in the world.

The C-Tech Advantages

C Tech is the most Advanced Cyclic Effluent Treatment Technology in the World. The technology is based on Activated Sludge process adapted to Sequential Batch reactor Technology. This technology was developed in the USA in the 80’s and has been adopted worldwide since 1990’s. Salient Features of this technology are:

Excellent quality of Treated effluent



Conventional Process


< 5

< 30


< 50

< 250


< 5

< 30


< 2

No treatment


< 1

No treatment

The treated sewage out of C Tech is 6 times better than any conventional treatment. This technology offers in built co current nitrification, de nitrification and bio – phosphorous removal mechanism that differentiates it from other technologies.

Recycle of treated sewage
C-Tech treated sewage is as good as raw water and can be recycled / sold for industrial and agriculture use. Customer can have additional source of revenue generation by sale of this water.

50% reduction in POWER consumption
C-Tech uses 50% less power as compared to conventional process to get 6 times better outlet characteristics. Hence the plant has a payback period.

50% reduction in Land Requirements
The main problem in Cities is the availability of Land. C Tech uses 50% less land area compared with other conventional Technologies, thus saving huge amounts on purchase of land.

Fully Automatic, Computerized, Internet Controlled
C-Tech is fully automatic, computer controlled. This does not require any operator attention. The plant can be operated from anywhere in the world through Internet. This results in huge savings on manpower and operating costs.

Excellent Material of construction
C-Tech uses all underwater metal parts in SS and non-metallic parts in imported PVC, the diffusers are in EPDM/PU and all pumps, instruments etc and from the best manufacturers worldwide. This result in a plant life 6 times better than conventional plants and very little maintenance costs.

Proved World Wide
C-Tech has installations in almost all countries in the world, Including, USA, UK, Germany, France, Austria, China, Russia, Australia, Thailand, Malaysia and most importantly India. Refer list of installations for plant details.

Capital and operating cost
C-Tech requires the lowest investment and operating costs as compared to any other technology, when compared on a like to like basis, with respect to outlet parameters, MOC, Land required and Power consumed.

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