CIMOGG has received numerous representations over the past couple of years asking it to take an active part in trying to find solutions to the problem of disposing of garbage (Municipal Solid Waste) in an environmentally-acceptable manner. At the same time, various experts, business promoters and ratepayers continue to speak and write a great deal about garbage in the media. Many of them believe they have reasonably simple answers to the problem of garbage disposal and that it is solely the remissness or mendacity of politicians and officials which prevents a quick solution from being effected. Whilst there is much justification for such a belief, there are also other factors which militate against a quick fix, the principal one being the shortage of funds.
When one studies the voluminous contributions made on this subject, it becomes clear that one would have to write a substantial book to cover in detail all the aspects which are relevant to this subject. Although there are undoubtedly many such books already written elsewhere, they are not freely available here and, in any case, we would have to make suitable modifications to meet local constraints. Even without resort to the sophisticated techniques discussed in such books, and even with our limited funds, we believe that a significant impact can be made in dealing with garbage by concentrating initially on what most of us could agree without much debate.
Separation of Degradable and Undegradable Wastes
The most obvious objections to the open dumping of garbage are the powerful stench of decomposing organic waste, the leaching out of aggressive, environmentally hazardous chemicals, and the offensive visual appearance of the dump itself. Here, as a first step, what is required, and is not difficult to do, is to convert all domestic organic refuse into compost within the householders’ premises itself. The space required for a compost bin is very small. No noxious gases are released during composting. The compost may be used in the householders’ gardens or, alternatively, arrangements can be made for it to be collected for use by horticultural or agricultural end users. The collection could be done by small-time, self-employed contractors.
As for the dry components of household garbage, there are two options. The less satisfactory one is to have all the mixed plastic, rubber, paper, wood, glass and metal items put in a single bin for removal on a fixed day of the week. The removal of these components would be fairly straightforward as there would be no objectionable smells and offensive dripping of liquids during handling and transport. Furthermore, there would no irreversible adverse environmental hazard. Those presently engaged in scavenging for recyclable materials in mixed, wet dumping grounds would be able to increase their productivity many-fold because they would now be working in dry conditions. Considering that there would be a substantial volume of the temporarily stored material being removed continuously for re-cycling, the land area required for the dumping and sorting of this residue would be much less than that which would have been required for the original wet mixed garbage.
A better variation of the above option would be for each household to compost the organic material, as before, but additionally sort the plastics & rubber, the paper & wood, the glass, and the metal & other items separately into four bins. However, this option would have a reasonable chance of being implemented properly only if (a) the required bins are provided at the cost of the local authority and the cost recovered over a period of, say, 5-10 years by enhancing the rates, (b) an intensive campaign is carried out in schools and through the written and visual media to get the population to cooperate, and (c) the collection of the different fractions is entrusted to contractors, on the lines referred to above.
Garbage from Hotels, Restaurants and Canteens
If a hotel, restaurant or canteen is located on a large plot, the composting could be done within the premises and the rest of the materials sorted out into the four bins, as for households. The removal of the compost and the other components would, in this case too, be entrusted to independent contractors. On the other hand, where there is no garden space, the local authority may use their existing trucks to transport the organic component to a number of small composting plants, run by the local authority, from where the contractors would collect the compost for sale to the end users.
Toxic Wastes from Hospitals
The wastes produced by hospitals would need to be separated into two basic components. Those wastes produced in hospital kitchens and restaurants could be separated and decomposed into compost and disposed of in the same way as in hotels. On the other hand, the plastic, paper, glass and metal wastes from hospitals and nursing homes would undoubtedly be contaminated with germs, drugs, disinfectants etc. These should not be burnt in the open air because there would be release of toxic gases and possible dispersal of contaminated dust and soot. Consequently, there is no alternative to having these materials destroyed by one of the custom-designed methods of incineration which have been developed for this purpose.
Thin-film Plastic Bags (Sili-sili bags) and Food-Wrapping Film
The proposal to ban thin film sili-sili bags is theoretically attractive but is not without major disadvantages.
There is no more hygienic and economical material for wrapping meat, fish or refrigerated products than plastic film. However, reuse is not practical at present because the regular plastic film is too thin and tears easily. One way of dealing with this would be to ban bags from being made with material of less than a certain specified thickness, and to make the user pay for them, which would greatly promote multiple reuse. Shops should be discouraged from giving away free bags. This could be done by the government levying a high rate of tax on the manufacture of these bags so that no one would want to throw them away prematurely. Another sensible alternative, and probably the better one in the long term, would be to encourage all manufacturers to use biodegradable raw materials for making sili-sili bags and food wrapping film. These raw materials are somewhat more expensive than those used for the standard film. Their chemical structures are so designed as to result in total degradation within 6-12 months unlike the more common materials which remain intact almost indefinitely.
We need to point out that paper, which has a very low wet strength and is porous, is not a satisfactory substitute for plastic film. It would cost more to produce, require huge numbers of trees to be cut down (either here or in another country) and would cost very much more to recycle. The production of paper and its recycling are also far more energy-consuming and environmentally problem-laden than plastic film. In addition, paper, on account of its porosity, is likely to increase the probability of contamination when used to wrap food items.
Lining of Garbage Dumps and Tapping of Methane for Power Production
The lining of garbage dumps to prevent groundwater pollution is technically more complicated than might appear at first glance. It is also an enormously expensive exercise to do correctly. If done without proper engineering inputs in respect of investigations, planning, designs, costing, construction, filling and covering with earth, it would represent money down the drain. In any event, large areas of land would still have to be found for the dumps and the land, when covered by soil (obtained by affecting adversely the environment somewhere else), would be suitable only as agricultural or park land, and possibly for small-scale power production for a limited number of years by tapping the methane produced within the enclosed fill.
The costs of properly engineered, lined and sealed landfills are extremely high and it is unlikely that Sri Lanka would be able to afford to resort to these in the foreseeable future.
Incineration without Separation
Incineration of unsorted garbage in large-scale plants tends to be favoured by businessmen and politicians because there is a lot of money involved in the financing, designing, building and operating of sophisticated, giant incinerating plants. Considerable technological inputs are required for the design of the incineration process and the plant so as avoid discharging dangerous gases and smoke into the atmosphere. Also, even before the design work could commence, a lot of time and resources will be needed for the necessary investigations into land availability, transport costs, capital costs, running costs, financial feasibility, sensitivity to industrial action, environmental impact etc. Thus, it can be readily appreciated that heavy incineration plants require several years to go from concept to completion.
This option should, nevertheless, not be ignored altogether. Preliminary studies should be carried out without delay and a decision taken on implementation at such time as it becomes difficult to get contractors to do the collection and disposal of the components and products of garbage as proposed in the earlier parts of this article.
Treatment of Mixed Wet Garbage by Chemicals
There has been brief reference in the press regarding the centralised sorting of mixed garbage and its treatment with a special patented digestive liquid (ADelta D) to break down all organic materials. The inventors of this system have recommended that a pilot project to convert 50 tonnes per day should be set up, which indicates that there is some way to go to before this method can be considered to be fully tested. However, as it has been developed by Sri Lankan scientists and engineers, it must be tried out, improved and the financial viability worked out. This will take some time but may prove to be the best direction in which we would need to go in the long term.
Readers are reminded that the garbage load in Colombo and its suburbs runs into a few thousand tonnes per day and it will be many years before this particular technology would be able to take over from the simpler ones outlined here.
Action by Central Government
To help deal with the disposal of garbage on the lines proposed here, the Central Government should take steps to do the following -
a) Get the State-controlled media to prepare on an urgent basis publicity and educational material to teach the younger generation – and, through them, the older generation – to show a greater degree of social responsibility to deal with garbage in a sustainable manner – composting, sorting, multiple reuse of plastic bags etc;
b) Get the state banks to give loans on easy terms for the leasing of mini-trucks to those who are prepared to become contractors for the collection and transport of compost and recyclable materials (both sorted and unsorted) to meet any existing shortages of equipment;
c) Release small plots of land for the temporary storage and sorting of the relatively inoffensive recyclable materials;
d) Help local authorities with loans to set up small-scale composting plants to deal with organic waste from large institutions such as hospitals, hotels, restaurants and so on;
e) Get the Department of Health to provide standards for the safe incineration of non-compostable waste from hospitals and set up small, standard-sized units, each to serve hospitals within a radius of, say, 5-10km;
f) Help local authorities with expertise to help them raise money on municipal and similar bonds to pay for the early implementation of proposals such as those proposed here, and guarantee the funds;
g) Ban, with a grace period of one or two years, thin-film products of all kinds unless they are biodegradable.
Action by Local Authority
a) Set up a dedicated task force to follow up actively on the above proposals;
b) Meet with Ministers, MPs and central government officials, and keep ratepayers informed regularly of the progress made so that the public could know quickly where things are getting stuck and bring appropriate pressure to bear on their representatives;
c) Inform all householders who have even a small area of open space outside their houses that they would have to use the compost bins provided and also sort their waste into the different categories into the other bins. Failure to cooperate would result in their rates being increased to, say, three times the standard figure or being subject to some other penalty to be determined by the local authority;
d) Allocate areas of work, collection programmes and payment schemes to match the contractors’ equipment, transport distance etc;
e) Divert underemployed cadres from existing cadres and train them to run the composting plants, and the final sorting and sale of recyclable materials.
Restrictions of space do not permit going into any more detail regarding the suggestions and proposals given here. However, there is a wealth of information available on these matters in our universities, research organisations and governmental and non-governmental institutions concerned with health, the environment and public services. It would be responsibility of the task force to tap these sources for such information and act on them.