Sustainability – this word has assumed tremendous importance today, in the context of “development”. The advancement of human civilization in terms of technology, economics and life-style is turning out to be lop-sided. It is being realized that the sheer amount of wastes generated by the present population, is becoming more and more unmanageable with each passing day. Man’s intelligence is, undoubtedly, succeeding in manipulating the forces of nature to fulfill his wants. But his enthusiasm in this direction needs to be coupled with an awareness of making his activities more “sustainable” in the long run.
Today, because of the interest in global warming, the topic of effective disposal of wastes couldn’t be more relevant. It is not that we have completely ignored the aspect of waste-disposal; application of modern science as well as common sense has resulted in the development of a variety of different technologies to treat waste-water, gaseous exhausts and solid wastes. The various techniques employed today can be broadly categorized into physical, chemical and biological techniques. As a representative example, let us consider the problem of wastewater-treatment. There are not less than 18 different ‘physical’ techniques, which can be applied at various stages of wastewater treatment – sedimentation, centrifugation, filtration and reverse osmosis to name a few. Industrial units and government bodies all over the world have put various systems in place for the effective functioning of these technologies at the local level. At many places, these conventional technologies are the crucial bearers of the load of waste-management.
Although effective, these systems have achieved only partial success, leaving lot of scope for improvement. Conventional technologies are necessary, but no longer sufficient. The staggering variety of wastes in today’s sewage is rendering the existing sewage treatment plants (STP’s) inadequate. Establishing such facilities is a capital-intensive as well as time-consuming process. In the developing world, where more than half of the world-population resides, developing STP’s and maintaining a particular standard efficiency of their functioning is a monumental task. STP’s require constant monitoring, and scarce or mismanaged resources, coupled with insufficient expertise create hurdles in the proper functioning of sewerage systems. Ineffective functioning of such systems is causing pollution on a ‘grand’ scale. This is particularly relevant in the Indian context.
There are about 233 Class-I cities in the 14 major river-basins of India, with a collective population of roughly 105 crores. These cities have been partially covered by their sewerage systems – 24% only. Therefore, around 76% of the untreated sewage from these cities reaches fresh-water bodies, mainly rivers and lakes. Class-II cities don’t have sewerage systems at all. Natural drains in these cities are serving as sewer lines. Given these facts, it doesn’t surprise us when we are told that even the holy Ganga, the national river of India, has, at some places along its course, become nothing but a huge drain! Every lake in India is, today, receiving wastes from regions upstream, the amount and nature of which is making the water unfit for any kind of use, even unfit for supporting aquatic life.
At this juncture, it is worthwhile to consider the significance of Ecotechnology. All sustainable engineering that can reduce damage to ecosystems, adapt ecology as a fundamental basis, and ensure an orientation of precaution in the conservation of biodiversity and implementation of sustainable development may be considered as forms of ecotechnology. Various techniques like phytoremediation and bioremediation are being used to treat different types of wastes including toxic wastes like phenolics, hydrocarbons and fertilizers. In ecotechnology, an attempt is made to apply natural flora and fauna in a well-designed manner to develop sustainable technologies. Many pollutants cease to be polluting if they find their way back into the bio-geo-chemical cycles, which is what is facilitated by the methods of ecotechnology.
As an example of an ecotechnological method, let us consider the Green Bridge Technology developed by Sandeep Joshi of Shrishti Eco Research Institute (SERI), Pune. It is a low-cost horizontal filtration technique in which a small bund called the Green Bridge is built across the water channel. Cellulosic material of biological origin, like coconut coir or dried water hyacinth or aquatic grasses, is compacted and woven to form a porous wall-like structure strengthened by stones and sand. As water passes through the bridge, all floatable and suspended solids are trapped in this eco-bridge and the turbidity of flowing water is reduced. Growth of bacteria is facilitated on the stones inside the Green Bridge. These bacteria fix the pollutants into nutrients for plants. The green plants that grow on the bridge absorb these nutrients, which also include heavy metals. This technology requires zero electricity and negligible maintenance. Its economical nature may also be highlighted, with capital expenditure being just 5 to 10 % of the total for conventional mechanized aerobic and anaerobic treatment systems. Construction of Green bridges along the main course has been instrumental in reviving the health of the river Ahar in Udaipur, Rajasthan.
The obvious effectiveness of ecotechnological techniques is something of a constructive challenge to the status quo! Their efficiencies are natural, hence optimum, because the processes utilized in ecotechnology are completely natural processes having natural biotic and abiotic components. Minimal use of electricity is an added advantage. Capital expenditure on ecotechnological systems is comparable with the annual operational cost for conventional bioremediation systems. It is not possible, at this stage of development of ecotech, to completely replace existing technologies and nor is there a need to do so. Ecotechnological systems can be developed and operated in combination with conventional systems to improve the performance of the latter. As such, they will only improve the efficiency of existing systems by sharing the load.
Never in the recent past has environmental sustainability of of our activities been emphasized as much as it is today. This clearly indicates that ecotechnology is here to stay. Moreover, India, with its glorious history of human beings living in harmony with nature, can and should play a pioneering role.