Development accompanied by the spread of social infrastructure has been essential to reduce poverty and inequality in developing countries. Water and sanitation infrastructure has proved to be particularly relevant. However, in spite of improving availability, the great majority of people in developing countries have to couple with very low coverage of sewage treatment plants. Sewer is usually disposed into watercourses without any treatment whatsoever.
This has had serious consequences in terms of spreading diseases and reducing well being, particularly of the poor. The main explanation for this low coverage is the required high investment costs of sewage treatment plants. On their turn, high investment costs are closely dependent of an engineer decision in terms of achieving high environmental standards for the sewage treated. This standard is usually aimed at 100% cleanup goal.
We argue that environmental standards should be based upon the optimum level of pollution subjected to safe health requirements and overall environmental gains. This means that investments on sewage treatment plants must be based on cost-effectiveness (CE) considerations, allowing a gradually crescent environmental standard implementation process. If CE procedure is followed, sewage treatment will have higher social gains per monetary unit of investment in the initial stages of implementation.
Data / Methods:
We have modeled two situations in implementing sewage treatment plants (STPs) using CE calculations: 1) the usual optimal engineering option aimed to attend the strict standard of pollution determined by regulations and 2) an equimarginal option, taking into consideration optimal pollution level. This second situation was modeled in terms of a four stage sewage plant implementation alternative, leading to a six disbursement parcels of equal values, for four fixed polluting loads of biochemical demand of oxygen (BDO), over a twenty years period. Data for Brazil have been used in our simulations.
Results:
Our results show that the equimarginal option has accumulated environmental gains that are higher than the usual optimal engineering option. The implementation in stages of four STP, throughout a 20 years period, in which occurred equally spaced disbursements of 6 fixed nominal values parcels, showed that CE analysis evidenced superior environmental gains of 68% in the second STP situation. Moreover, the initial gains in the second situation were much superior than those in the first one, since environmental and social gains are achieved much earlier, just after the initial disbursement parcel. In the very first disbursement, the ratio between the achieved levels of protection was 3.75 superior in the second STP situation.
Even though it seems a paradox, results show that a higher environmental protection can be achieved by lowering standards in the first stages of STP implementations, meaning that an immediate reduction in actual environmental standards will lead to a higher environmental protection pattern. An immediate reduction in actual environmental standards will lead to a higher environmental protection pattern. Our findings are particularly relevant to those developing countries with strong financial and economic restrictions to invest in projects to reduce poverty and inequality but that have very high initial investment requirements and long payback periods.