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Neutralising industrial waste with worms
Vermicomposting to convert household waste into manure is
widely used worldwide, but using it to treat toxic waste is relatively recent
and yet to gain acceptance. Surekha Sule reports on the
work of Dr.Suneet Dabke.
September 2004 - True, thousands of small scale
and even some bigger industrial units simply dump their waste, more often toxic
and hazardous, in open spaces and nearby water sources. Over the last three
decades, many cases of serious and permanent damage to environment by these
industries have come to the fore.
While strict pollution control norms are in place, they are
dodged by many industrial units either hoodwinking or ‘managing’ the state
pollution control boards. However, there is gradual change of the mindset and in
the attitudes of the people running manufacturing business. And some industries
are making attempts to keep up to the norms and trying innovative methods, may
be to get ISO 14000 certification.
The latest that is happening in pollution control is the
research on vermicomposting of industrial sludge being tested out in some
industries. Dr Suneet Dabke is putting his research on vermicomposting of toxic
industrial waste into practice for the last 3-4 years. It is only after
observing the results over fairly long period that he would be able to establish
this process as an answer to managing the industrial waste issue. Dabke is based
in Gujarat.
The present technologies for disposal of solid waste are
either incineration or landfilling (may be so-called scientific land filling).
But the disadvantages of these methods are well known. While incineration causes
serious air pollution as also generates residual highly concentrated toxic ash,
mere dumping or landfilling causes hazards of leachate polluting soil and ground
water. Scientific landfilling claims to be safer, yet landfilling of any type
needs much land. The other technology is composting by spreading out the waste
on land. This also takes up land, and is accompanied by serious problems of
direct soil contamination.
However, Dr Dabke’s method works on the sludge that remains
after the effluent treatment. Bigger industries can afford their own effluent
treatment plant while smaller units can join together to send their effluents
treated as per the PCB norms within the factory to the common effluent treatment
plants (CETP) for further treatment. While the sludge settles down, the clearer
water outflows into outer drainage system. It is this sludge which still has
about 70-80 per cent water and can be dewatered by a belt press filter. The
remaining 20-30 per cent solid sludge contains organic as well as inorganic
material. Depending upon the characterisation of the sludge, a predetermined
proportion is spread on a vermiculture bed that uses earthworms. Like in
conventional vermicomposting, the organic matter from the sludge gets converted
into manure. Simply put, this is the process.
But what happens to the toxic materials such as heavy metal compounds in the
sludge? These can kill earthworms. Yes, says Dabke, confirming that the toxic
material gets adsorbed by the earthworms. However, his research shows that while
the average life of earthworms is one and half year, depending upon the
concentration of the toxic matter, it reduces to 6-8 months. Even within this
shortened span of life, earthworms regenerate 10-20 times. Dead worms too form
organic matter. The same quantity of toxic matter gets distributed in multiplied
worms leaving manure toxic free, claims Dabke. As a proof of the manure's
non-toxic nature, he shows centipedes and ants in the vermiculture beds.
Having developed this concept after testing number of batches
with different proportions of industrial sludge and vermiculture (cowdung,
bagasse, leaf litter), Dabke has provided it to some medium to large-scale
industrial units over last three-four years. Some of the projects executed are
treatment of textile sludge of Jagdamba Textile at Narol and Samir Textiles at
Odhav in Gujarat; Gujarat Refinery waste into non-toxic manure; paper industry
sludge of Vepar Pvt Ltd at Ahmedabad; Dairy waste of Mother Dairy at Gandhinagar;
pharma sludge of Aventis Crop Science and Lupin Lab at Ankleshwar; Torrent
Pharma at Mehsana in Gujarat. Currently he is working on the pilot projects at
Reliance industries’ Hazira as well as Patalganaga plants.
Dabke, however, says a strict no to waste from dyes and
intermediates industrial units as these have a very high proportion of inorganic
compounds in their waste. Thus industrial waste sludge that has good proportion
of organic matter can be converted into non-toxic manure, thinks Dabke and hence
is suitable for textile industry, oil refinery, dairy, distilleries, pulp and
paper industry, food processing, agro industries etc. His approach is to carry a
detailed characterization of the waste, take up controlled experiments, then
large scale experiments and only after establishing the desired results over a
sufficiently long period, go in for industrial application.
If vermicomposting toxic industrial waste has proved to be
successful, why is it not finding large scale acceptance by the industry as also
administration? Dr Dabke’s research referee Dr Radha Kale of University of
Agriculture Science in Bangalore, has been similarly providing solutions to
distilleries in Karnataka. The state’s pollution control board (KPCB) has
already given the consent to this process. However, the Gujarat Pollution
Control Board (GPCB) and Maharashtra Pollution Control Board (MPCB) do not seem
convinced and have not given their consent. Besides, environmentalists also do
not seem very convinced and remain somewhat apprehensive about the process.
According to environmental activists fighting against rampant
industrial pollution in Gujarat, any kind of work on industrial sludge or
effluent is possible only after detailed characterisation of the waste. No such
detailed characterisation of the waste streams in Gujarat has been reported so
far, according to them. The best has been done by NEERI for the Amla Khadi of
Ankleshwar, but that too was without identifying a single chemical; the study
reported loads of carbon, chlorine, etc., only in aggregate levels. The only
other good one is done by Greenpeace, but they were only looking for chlorinated
organics and heavy metals. Besides such detailed characterization is extremely
costly affair.
Environmentalists say that each sample (and one would have to
do many, and over a significant period of time) analysis would cost upwards of
Rs 30,000 for detailed characterisation, and that too with highly skilled
personnel. There is a doubt that whether such facilities exist in India at all.
And in fact, for dioxins, India has only two experts in India, and on last
count, no testing facility. Like waste, similar characterisation of the
vermicompost produced would have to done. So imagine how expensive it would be.
But the question is also about the level of characterization
of sludge that is really necessary. Most experts agree that detailed
characterisation is expensive. But according to Dabke, characterization need not
be that costly. Dabke gets a total load estimate which is not so expensive, but
enough to make the decision. (The load estimate is for the level of
organic/inorganic compounds in the sludge at the input to the VC process).
However, on estimation of toxicity for post-compost residue, Dabke acknowledges
that because many batches of sludge need to undergo composting over a
considerably long period of time, establishing this level is a time consuming
process.
On the operational side, the whole job is made extremely
difficult by the fact that the waste streams keep on changing. And therefore it
is impossible to have one method of treatment for all these types. Often the
volume of the sludge (or effluent) may be too large making it unviable to treat
the waste in any sensible manner, opine environmentalists.
Acoording to an expert on pathways of environmental
pollutants from University of Colorado, even if the effluent or sludge could be
treated, a leftover sludge would be so toxic and persistent that it would demand
much specialised care and technique to store, let alone treat. Because of these
extreme difficulties encountered in treating toxic waste and prohibitive costs
incurred, environmentalists toe the extreme hardline that the only way out is
not to produce waste.
But that agreed, the reality also cannot be wished away with
the monster of industrial pollution gaping straight in our faces. Having created
a system that generates industrial waste in the absence of workable controls,
what are the options? Will vermicomposting of at least the industrial
waste/sludge that has high proportion of organic waste be an answer at the plant
level, if not at the collective stage like CETPs? The application may be
industry specific and not a wholesale adoption by the industry sector.
As Dabke puts it, ideally industries should process the
biological waste and send the difficult waste to the scientific landfill sites.
With vermicomposting, there would be considerable reduction in the volume going
to legal landfill or illegal dumping grounds. As per Dr Dabke, the conversion
costs are not prohibitive at Rs 3-4 per kg of sludge as against Rs 5-6 per kg
for sending it to landfill. ⊕
Surekha
Sule
September 2004
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