Tuesday, 5 July 2011

The greenest and the most sustainable technology for waste water treatment


Soil Bio technology 

 IIT Bombay Technology

Covered by US patent 6890438 B2 and 2 other Indian patents

1.     What is Sewage/Waste Water

Sewage/ Wastewater – is essentially the water supply of the community after it has been fouled by a variety of uses.  From the standpoint of sources of generation, waste water may be defined as a combination of the liquid (or water) carrying wastes removed from residences, institutions, and commercial and industrial establishments, together with such groundwater, surface water, and storm water as may be present. 
Generally, the wastewater discharged from domestic premises like residences, institutions, and commercial establishments is termed as “Sewage / Community wastewater”. It comprises of 99.9% water and 0.1% solids and is organic because it consists of carbon compounds like human waste, paper, vegetable matter etc. Besides community wastewater / sewage, there is industrial wastewater in the region. Many industrial wastes are also organic in composition and can be treated physico-chemically and/or by micro-organisms in the same way as sewage.

2.     Basic philosophy of Waste water treatment

The waste water treatment process involves breakdown of complex organic compounds by the means of oxidation. In a typical STP, effluent quality is primarily dependent on effectiveness of aeration. Conventional waste water treatment processes use aerators (blowers) to fulfill the oxygen demand. As air contains only 20% of oxygen and the rest is nitrogen, this process is highly inefficient. Further, diffusion coefficient of oxygen in water is lower (~10-9 m2/s) than that in soil (~10-4 m2/s). This implies that oxidation of pollutants is much easier if done in soil than that in water.

3.     What is Soil Bio-Technology

3.1  Introduction

Human and animal habitations generate large quantities of organic wastes. In modern urban environment these wastes accumulate in our neighborhood and endanger the health of our lifeline – the land, water and air. Traditionally organics have always been returned to soil. However, the urbanization phenomenon of the last 50 years these practices have fallen in to disuse.

Water is a scarce resource. Water treatment provides usable water for domestic agricultural & industrial purposes; helps to conserve & enhance water in quality & quantity; in addition prevents degeneration of our water sources of surface & ground. Therefore, a total water purification solution is the need of the hour. Green technologies today provide impressive water quality at competitive costs without contributing to global warming. This technical specification presents a green biological purification engine using a natural novel high efficiency oxidation process variably known as SBT (Soil Biotechnology) developed at IIT Bombay by Prof H. S. Shankar & his students. Soil Biotechnology (or SBT) is covered by one US patent (Patent no 6890438 B2) and 2 other Indian patents all assigned to IIT Bombay.

3.2  Process

The technology is based on a bio-conversion process where fundamental reactions of nature, namely respiration, photosynthesis & mineral weathering take place in a media housing micro & macro organisms which bring about the desired purification. SBT is an oxygen supplying biological engine and so the process can treat all types of waste water – domestic, municipal & industrial. SBT is suitable for treating water with salinity <2500mg/L.

The process requires mesophyllic temperatures; so where the ambient temperatures very low (< -5°C) a greenhouse infrastructure appropriate for the local conditions houses the SBT plant. However the process can work at high ambient temperatures.

The facilities of a treatment process for water & waste water consists of a raw water tank, bioreactor containment, treated water tank and where appropriate  a greenhouse and associated piping, pumps & electrical.

The waste water is collected in a collection tank where primary settling takes place. After this the water is pumped over the bioreactor where it trickles into the bed and treated water gets collected in the filtrate tank. Recirculation pumps are provided to obtain desired hydraulic retention times; in general purification to desired quality is achieved in one pass and so these recirculation pumps are not used.

The scheme for drinking quality raw water, swimming pool water, rain water & storm water & waste water treatment are identical to description above

The layout of media on the bioreactor is shown in Fig 3.2 .The specific layout engaged depends on site conditions.

Fig 3.2: Layout of SBT Media for waste water treatment

3.3  Building & equipment

SBT plant is essentially a civil structure. However the civil structure can be also all steel, if required; for small capacities this may be ideal.  It comprises of containment, bioreactor containment & a pump room and piping & pumping arrangements.

Water treatment: Raw water tank, treated water tank & bioreactor containment, pump cum store room constitute the civil structure of the SBT plant. Fig 3.2 shows the types of layout of media; several other alternative layouts are also available but not shown here. The choice of media layout depends on process requirements. The civil structure of the SBT plant is typically of stone rubble or RCC, steel and sometimes soil embankment.

In addition a green house infrastructure for very cold climates also forms a part of the SBT plant; the green house infrastructure is typically a bought out item. The piping system for the SBT plant is typically of 8 kg/cm2 HDPE pipes; but PVC & GI or other materials as per site conditions. All valves compatible with high pressure corrosion free service is fine for SBT plant.

Pumps are typically self priming & submersible type as per site conditions. All electrical cables switches alarms monitors & displays are as per design & safety requirements of the process on hand.

The details above also apply for primary purification of raw water from surface sources for drinking purposes; also for rain water, storm water, swimming pool water treatments. For these applications the SBT treated water is subjected to disinfection as per norms prior to delivery to end user.

3.4  Construction of SBT plant

Water purification Process Specification: The specifications for containment & bioreactor required to treat water & waste water, solid & hospital waste are obtained from process models & laboratory investigations.

The construction of the SBT plant involves essentially civil works; design follows standard civil engineering procedures. 

3.5  Safety

The SBT process involves no moving parts excepting feed & discharge pumps. So safety needs are minimal. However gloves & gum boots are required while handling solids and during movements in the plant area so that accidental fall into tanks are avoided. Accordingly all tanks are provided closures and ladders.

3.6  Personnel training

Personnel training required are i) routine pump operation & maintenance ii) routine O&M of plantations. These instructions are imparted during commissioning and trial run period.

3.7  O&M of SBT Plant

The water purification plant works on the principle of Soil Biotechnology that applies the biochemistry of nature in a concentrated manner. It aims at enriching soil & extracting excellent water for use in drinking, irrigation, fisheries, industries & construction & fire- fighting.
O&M of pumps & pipes: All pumps should be run daily to ascertain maintenance requirements. All monitors & alarms should be checked daily. All pipe ports should be maintained daily to ensure that water flows out of all the ports. All valves & fittings should be checked and where faulty should be restored.
Plantation: The plantation on the bioreactor and surroundings should be regularly watered pruned, replaced and provided with manure as required.
Tanks: All tanks should be cleaned thoroughly as per norms (once in a year).

3.8  Advantages of SBT

SBT is an oxygenation engine that outperforms conventional technologies like Activated Sludge Process (ASP), Sequential Batch Reactor (SBR), Membrane Bio Reactor (MBR) and Moving Bed Bio reactor (MBBR). Our technology harnesses a special set of biochemical reactions to deliver the oxygenation required for effluent treatment. 

In conventional technologies, aeration is achieved mechanically, which is very energy intensive. At higher ambient temperatures (like in India) the solubility of oxygen in water is low, therefore energy requirements of mechanical aeration used by conventional technology increases. Moreover, air contains only 20% oxygen, the rest being nitrogen that is passed into water wastefully, further adding to process inefficiency.

SBT resolves this problem using a biochemical method of oxygenation, which not only uses the atmospheric oxygen, but also uses the nitrogen from the atmosphere in a specially engineered natural ecology to achieve the desired level of purity. In addition conventional technologies generate large amount of sludge for which additional disposal facilities have to be created. SBT does not face any such problems.

Advantages of SBT:
-    Complete water recycling resulting in reduced water intake
-    Oxygen rich and completely odour free treated water
-    Capable of delivering drinking water quality
-    Low/negligible operation and maintenance cost
o   No moving parts
o   No skilled workers required
o   Significantly reduced energy consumption
-    Highest rate of Return On Investment (ROI)
-    Forms a part of green cover in the layout
o   It is installable on any available land area irrespective of the shape

3.9  Disadvantages of SBT

-          Marginally higher capital requirement (~1.3 times)
o   Compensated by highest ROI among all technologies
-          Bigger land area requirement
o   The installation site will form a part of the green cover

3.10   Conclusion

SBT is a novel green technology for purification of air & water & for processing of organic solids.

4.     List of SBT plants in India

SBT has been successfully implemented across industries and housing societies. The capacity of installations ranges from 1 kLD to 3 MLD.

Following are some selected implementations:

-          Mumbai Rail Vikas Corporation, Mumbai (2011)

-          Naval Dockyard, Bombay (2000)
-          Vazir Sultan Tobacco, Hyderabad (2004)
-          Godrej, Pondicherry (2009)
-          Navneet Publications, Silvassa (2011)

Housing societies
-          Naval Housing Colony, Bombay (2001)
-          Shamik Builders, Lonavala (2009

-          Bombay Presidency Golf Club (1996,2003)
-          Shilim Resort, Lonavala (2008)
-          Nature Trail, Lavasa, Pune (2009)

-          Beru Ashram Badlapur (2003)
-          University of Hyderabad, Hyderabad (2005)
-          IIT Bombay, Mumbai (2006)
-          Vanvasi Kalyan Ashram, Mangoan (2008)

-          Taj Kiran, Gwalior (2003)

Municipal Corporations
-          Bombay Municipal Corp., Mumbai (2006)
-          Kalyan Dombivli Municipal Corp.(2009)

-          Maharana Pratap Air Port, Udaipur (2007)

-          Foundation for Revitalisation of Local Health Traditions, FRLHT Bangaluru (2010)
-          Command Hospital Air Force, CHAF Bangaluru (in progress)

5.     FAQs

Q.1. Why Soil Biotechnology?
All existing technologies are aquatic and require intense aeration and hence have high energy consumption. In contrast in SBT uses lithospheric environment with diverse microbiology. Very low energy consumption & internal oxygen generation are some prominent features of this green technology.

Q. 2. What are the economic features of SBT (typically for 1 MLD)?
Land:  800 to 900 m2
Investment: Rs. 120 to 130 lakh
O&M cost:  Rs. 3 - 3.5 per cum
Power: 0.03 to 0.05 kWh/cum

Q. 3. What is meant by media, culture & additives in SBT?
SBT houses an engineered ecology of formulated media containing selected micro- and macro-organisms such as the geophagus worm, ammonia oxidizers, nitrifiers,  enitrifiers, proteolytic bacteria, actinomycetes protozoa, naked amoebae, flagellates, and ciliates etc. which are cultured to maintain the required soil microbial ecology. Refer US patent (Shankar, 2005) for details.

Q. 4. What is the scope for Carbon credit in SBT (for 1 MLD)? 
There is scope for Carbon credit of 100 tonnes of CO2 currently selling U $ 12 per ton CO2

Q. 5. What is the effluent quality of SBT?

Effluent Water Parameters for different technologies
Drinking Water Source Standard

*All values are in mg/ltr

Q. 6. What is retention time in SBT?
Typical Retention time in SBT is 3- 5 hrs for 99 % COD removal. 

Q. 7. What is the minimum size or capacity we go for SBT?
Any capacity can be built. It is applicable for as small as 0.5 KLD to hundreds of MLD. Other technologies are not viable at less than 10 MLD. So for small scale SBT is particularly suitable.

Q. 10. Is it fit for industrial wastewater or not?
SBT can be used for removing organics from industrial or domestic sewage.

Q. 11. What is the capital and maintenance costs associated with SBT? Is return of investment (ROI) possible in case of SBT?
Actually compared to other available technologies like ASP, SBR, MBR, CW, the cost is very low (practically nil).
Comparative technology commercials are as follows:

Capital Cost  (per 100kld treatment plant) in Lakhs
Depends on membrane
Operational Cost (includes manpower, chemical & electrical expenses) in Rs/kl

ROI calculation for different technologies has been carried out and is presented below. The cost of treated water (sellable) is assumed to be INR 15.

Projected yearly revenue for 100 KLD (in Rs.)
Payback Period (in yrs)
(no ROI)

Q. 12. Does SBT works in high salinity?
Yes, but only up to 2500 ppm. Beyond that with special measures and salinity control system is required.

Q. 13. What is the function of plantations? Is some particular type of plants or any depending upon the region?
Plantations are the bio-indicator of health of SBT; whether system is working well or not. If plants show signs of wilting mean low pH so additive, flow control management is required   
Q. 14. Can we use SBT for groundwater recharge?
Yes, we can use SBT for GW recharge. Treated wastewater as per norms of GWR and
send it to ground which recharge the GW level and replenish the wells.

6.     Contact Details

Green Brick Eco Solutions Pvt. Ltd.
Website: www.gbes.in

Sandeep Garg (B.Tech, IIT Delhi)

Dhawal Parate (B.Tech IIT Delhi)


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