Soil Bio Technology type vermifiltration systems developed at IIT Bombay

  • cshankar
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Re: Soil Bio Technology type vermifiltration systems developed at IIT Bombay

To answer the questions by Pawan:

pkjha wrote: Dear All

In addition to the queries raised by Dean I would like to know:
- Question: Land required for the treatment of wastewater from 25000 people :

Answer: 0.6 sqm/KLD assuming 100 LPCD sewage generation from a 135 LPCD water supply @75% collection efficiency

- Question: Total capital cost excluding land cost and including land cost for the treatment of influent,

Answer: CAPEX is Rs 1.3Cr- Rs1.6Cr / MLD excluding land cost (valid for 1 MLD or larger). But this estimate is very generalized... depending on the client the costs may vary especially if very high quality RCC construction is demanded by codes. It is cheaper when Soil Bund Construction is used however area required increases

- Question: Total capital cost for the treatment of settle sludge

Answer: Included in estimate above

- Question: Recurring costs ( Operation and maintenance cost) on monthly / yearly basis including manpower, materials etc.

Answer: Very dependent on number of operators... assuming 2 operators 1 MLD plant O&M cost is Rs 11 Lakhs / year inclusive of power

- Question: Econmic return from the whole system with some details

Answer: Assuming treated water to be sold at Rs 30/KL plant payback is ~2 years. Potentially construction bamboo can be harvested from the top of the BM but has not been commercially tried as yet. Commercial Flowers are another possibility (Marigold and Hibiscus). Fish especially catfish grow in the treated water.. not sure if they will pass any kind of food safety test

- Question: Physico-chemical and bacteriological anayses of influent and effluent of the treated wastewater.

Answer: Inlet: COD~450,BOD~200,TSS~250 and Outlet:COD<50,BOD<10,TSS<10

- Question: 1st sample in plastic bottle showing as raw sewage does not appear a typical sewage, as it is much clear than a typical sewage in India. It appears to be mixed with storm water drainage.

Answer: Many plants exist... inlet parameters varies... inlet of COD~1000 treated to COD<50 is also available. Connect with me on whatsapp and I will be happy to arrange site visits etc
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  • goeco
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Re: Soil Bio Technology type vermifiltration systems developed at IIT Bombay

To me this still comes across to me as a duplicitous scheme to monopolise the technology for profit. Nowhere in the patent does it specify sizing of the process units in the context of parameters relevant to sustainability. The patent sets the stage for marketing of special media and special preparations that are proprietary, but the buyer must rely on good faith that such preparations make the product better than alternatives. In reality, design of reactor capacity involves authentic variables such as quantity, quality and oxygen demand of the influent, along with ambient temperature. Such process kinetics cannot be patented, so perhaps the special preparations were included to elucidate the patent? As a vermifiltration researcher I have found that such preparations are totally unnecessary to effectively treat wastewater. 

Redworms do not like wet conditions and vermifiltration using redworm systems resulted in loss of hydraulics over time. This feature was understood and solved by using the geophagus worm cultures.

Loss of hydraulic conductivity simply means that unsuitable media was deployed in the first place. Earthworms add to the substrate by creating humus, but this humus inherently holds porosity and conductivity suitable for earthworm habitat. SBT "geophagus worm cultures" are not a magic bullet solution to poor quality media with a low hydraulic conductivity... Appropriate media is the solution. 
Show me impartial, replicated science showing the "special" "geophagus earthworm cultures" improve media hydraulic conductivity. "Geophagus earthworm" is certainly a novel term suitable for glossy promotional brochures, but can a patent monopolise the combination of white and red worms? I can't see that being upheld in court, any earthworm can be added to any vermifiltration system and whatever earthworm species or colour survive the competitive environment inside the reactor are the ones that go into the next reactor... this is hardly proprietary or patentable. Even just claiming that Pheretima elongata fills an ecological niche inside the reactor (i.e. consuming bacterial film) to me is hollow rhetoric. Redworms build up to large numbers consuming only bacterial slime ("soil bacteria") in the absence of any fecal solids. It's simple... if the wastewater has a high oxygen demand and the substrate is aerobic, bacteria soon colonise it and consume the organics. That is the process. Worms graze the bacterial slime (biofilm) and control its buildup, they are just the system "caretakers". By grazing the biofilm, worms prevent it from building up and sloughing, overcoming the chief problem with the vermifilter's predecessor, the "trickling filter". 

The novelty is the use of adsorbtive / absorbtive media wherein the organics in waste water are transfered to to solid surface where soil rather than aquatic bacteria provide the treatment action.

 
Actually the fundamentals of vermifiltration are that micro-organisms fix to the surface of the media, which is not actually submerged in water, but has water trickling through it. One could surmise that the fauna which attach to the media are therefore not aquatic, but could be described as "soil bacteria" for novel effect. However, suitable bacteria colonise any surface with wastewater trickling over it.
Show me impartial, replicated science showing the "special" SBT bacteria are superior to "ordinary" bacteria that naturally colonise the media surface. Show me impartial, replicated science showing the "special" SBT media is superior to "ordinary" vermifilter media such as composted bark, woodchips and sawdust. 

Two other points I would make are that:
  1. Vermifiltration does not remove nitrogen and phosphorous from wastewater. Vermifiltration offers a low cost method for treating wastewater that retains the nutrients for application to land. Removal of nitrogen and phosphorous are appropriate where the water is discharged to waterways, because those nutrients can cause water bodies to become eutrophic. Removing nitrogen requires conventional sewage treatment processes such as anaerobic denitrification. Vermifiltration instead offers a method to close the nutrient cycle and recycle nutrients back onto the land for growing plants, whether irrigated to pasture, crops, trees or forests. If removal of N and P is required because the wastewater is to be discharged to a waterway, then another treatment process should be used.
  2. To date vermifiltration has had limited uptake because the companies deploying it haven't yet discovered the huge potential for efficiency improvement from a simple innovation that overcomes anoxic conditions that manifest deeper in the media. Take a look at the Animated walkthrough video above, the Camus SBT vermifilter reactor is just like all the other first generation reactors being produced around the world, the deeper you go into the media, the more it becomes oxygen limited. Although ventilation is generally provided at the bottom,  oxygen-limited zones occur in the centre of the mass because of distance from oxygen source.
In contrast here is a second generation design . The method allows unlimited media depth without being oxygen limited, which vastly improves treatment efficiency (and I would argue cost efficiency) in both recirculating and single pass systems. The deeper the media, the greater the level of treatment, provided the media is well aerated throughout the column.

cheers
Dean

Dean Satchell, M For. Sc.
Vermifilter.com
www.vermifilter.com
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  • cshankar
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Re: Soil Bio Technology type vermifiltration systems developed at IIT Bombay

Yes! There is a monopoly via the patent and as your rightly mention it may seem duplicitous to you as what is obvious to you today was not obvious back in 2000 and from what you write is still not obvious to most experts and therefore eminently patentable. Our firm is currently set up as a profit making entity though there are reasons that may compel us to explore being a non profit in order to scale the technology worldwide.

Many workers have re-discovered what our group at IIT Bombay innovated and demonstrated in 1990s that you can have deep beds 4m+ which are engineered to be aerobic due to perforated aeration pipes inserted to allow Air to access deeper regions. Your variation of the plastic lamella works on a similar principle. We at IIT Bombay also initially tried out wood bark, coco peat, other other organic matter only to discover that the biological breakdown of this organic matter by redworms mediated biology causes TSS/Humus to show up in the treated water and not to mention that organic media needs constant replacement. On the other hand SBT media is one time and needs near zero replacement. As far as demonstrations are concerned there are many in India close to 100MLD of installations and more are coming up all the time. We found during our extensive trials that deep beds there is higher shear forces due to higher hydraulic velocity (Q/A). This washes out the bacterial film and hastens the breakup of the already degrading organic mulch.

It is precisely this novelty that other implementations of Vermifiltrations do not have. SBT is designed for reuse to higher standards (COD<50, BOD<10, TSS<10) and also has features to allow removal of N and P from the waste water. this is achieved partly by biology and partly by well known process chemistry.

The patent is only one aspect which you may be well aware is only enforceable in areas where the IP systems are strong. In India there are many who have copied what we have demonstrated over the years... we have no time to pursue such entities... the only issue we face is when other Vermifiltration entities fail to deliver the entire technology is considered a failure much to our detriment in the market.

VEC works on demonstrated guarantees to its clients that we will deliver what we promise in terms of outcomes. So we are ok with folks calling their systems Vermifiltration using Organic Media and we call ours Soil Bio Technology and / OR CAMUS-SBT (both terms are trademarked) to develop the technology brand differentiation.
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  • goeco
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Re: Soil Bio Technology type vermifiltration systems developed at IIT Bombay

Hi cshankar,
Actually, I'd submit that such a monopoly is duplicitous because SBT have not provided any novel process in their patent. This was as obvious back in 2000 as it is today. You have not yet described anything novel about it beyond special proprietary ingredients whose novelty cannot be objectively evaluated. Could I suggest that you are not trying to enforce it because you have no basis for this?

Perforated pipes have been used for a long time in first generation vermifilters. These pipes are designed to get air into the sub-floor space (or in the case of SBT the "under drain" rock layer), to provide ventilation under the media for a reasonably aerobic substrate:


This does not give depth of aeration right into the media. The deeper the media, the smaller the aerobic zone becomes as a proportion of the media volume. 

With vertical perforated pipes it is only the perforations themselves that provide surface area. Such ventilation pipes would need to be placed 50cm apart through the media for a fully aerobic and deep media. This isn't done because it isn't cost effective... treatment efficiency is the tradeoff. In contrast, second generation vermifilters are fully aerobic by design. That said, the SBT substrate with its high proportion of anaerobic zones would remove nitrogen via anaerobic ammonium oxidation, but a greater surface area (and aerobic media volume) would be required to remove BOD. I repeat, removal of nitrogen should not be the aim of vermifiltration - cost-effective removal of oxygen demand should be.

Cshankar, did your trials with deep beds fail because of poor experimental design? Excessive velocity surely only arises because surface area is insufficient for the influent volume. Surely depth of media should be properly matched to total media volume and hydraulic loading rate, with the response variable being an optimised treatment level? Of course media porosity (and hydraulic retention time/recirculation frequency) are also important explanatory variables to get right, but I don't understand how your trials could get depth of media so wrong, such that hydraulic velocity caused failure? Is this trial published?

If bark and woody material (woodchips, sawdust etc) are pre-composted, the material does not break down further in the reactor, because decomposition has already taken place. Fresh sawdust, woodchips or bark are used because they are cheap, but it is accepted that these will need regular topping up over the short term, which is just a maintenance issue. Media replacement is certainly not necessary. As the media stabilises into humus, top ups become less frequent and once the substrate is humus-based it is very stable. The very best media is the product of vermifiltration itself - the humus that worms produce.

These materials are all organic for a reason and only one media form is required without layering. Organic media offers optimised porosity and the best surface area... and as worms add more humus as castings, the media remains optimised and 100% organic. Because primary (solid waste) vermidigesters generate larger quantities of humus, the excess is a valuable product for use as media in secondary reactors. Human solid waste makes the very best media of all - worm humus. Unfortunately it appears that SBT use an anaerobic conventional treatment process for dealing with solids (as per the videos above), so only generate sludge, which is useless as media.

Sorry, but I don't buy claims are that your proprietary SBT media is superior. Because SBT uses inorganic media (soil, granular inorganic media, sand, gravel layers and special ground rock additives), porosity is optimised by design (particle size and layering). However, as organic matter (castings/humus) builds up, HRT increases. This is because inorganic particles rely on inter-particle spaces, which get filled with organic material. The inorganic material then impedes flow because it is impermeable. The media becomes oxygen-limited and the worms hang out near the surface, forfeiting useful capacity. Once inorganic particle spaces are all filled up with vermi-humus, inevitably the inorganic media will impede flow, reduce surface area, reduce available oxygen and increase hydraulic retention time. Sure, the system might work for some time with a reducing hydraulic loading rate, but eventually the media will need replacing.

Although the future of the technology itself is assured, unless I can be convinced otherwise, my opinion remains that the SBT vermifilter is first generation outdated technology. Cshankar, beware that while you cling to methods developed 20 years ago, the art itself continues to move forward and you risk being left behind.
cheers
Dean

Dean Satchell, M For. Sc.
Vermifilter.com
www.vermifilter.com
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