Wastes. No I am not writing about our wasteful consumption habits or what we currently do with our household or industrial wastes. It is about faecal wastes. It is not quite on the scale of the Haiti crisis but it is nevertheless a crisis, almost obscured by the glitter of the rest of our infrastructure.

The stories are coming fast and furious. A defective sewerage treatment plant in Moka spilling raw sewage into the Maraval River, followed by the leaking latrines in Laventille. Similar in many ways but different in others.

In the first is a package treatment plant fully approved by planning authorities for an upscale housing estate that functioned for a time, eventually failing on account probably of lack of routine maintenance. The other is a row of pit latrines in an overcrowded settlement in Laventille, an economically depressed area on the edge of the capital city. Both make depressing reading.

But two notable things about both examples are, first, they are not uncommon in many parts of the country, up or downscale, and, that package sewage treatment plants and pit latrines can be appropriate and safe under certain conditions, if they are maintained and if their use is limited to their carrying capacities.

In the absence of connection to a centralised sewage treatment facility a package treatment plant is an option, especially if there are large numbers of units.

A pit latrine is also appropriate in many rural areas particularly where, the population density is low. In both, the processes of treatment are biological degradation but like any other system there is the common factor of the carrying capacity. Overload the systems through lack of maintenance or use they both fail. In between there is the option of the well proven septic tank and soak away, which if maintained, that is pumped out periodically, works for decades.

Human wastes are like any other animal wastes, including the carbon dioxide in our breath exhaled, urea and a few other trace metabolites and other chemicals in urine, and the solid wastes of undigested materials, some metabolites and various micro-organisms including pathogens.

The fate of these excretory products is well known even to children. The carbon dioxide and the urea are utilised by plants in their metabolism. Faeces are continuously degraded by micro-organisms and products recycled mainly in plants. Indeed the processes of biodegradation of faeces are essentially the same in all processes. The problem, however, is that these processes can be overloaded to the point of collapse.

Much, of course, seems to have been made of raw sewage entering the Maraval River as water is extracted from it at the reservoir that goes back to the 19th century. Although I do not know the details of the actual treatment there, my guess is that there must be some sort of flocculation or sedimentation process to remove solids followed by chlorination to kill pathogens, making the water biologically safe.

Bearing in mind however, that the Maraval River also receives all residential and commercial wastewater from the valley, there is no doubt the raw water treated at the reservoir will be a highly mixed cocktail containing many chemicals, including pesticides. Whether the water is chemically safe will be a matter for WASA to inform its customers about.

Regarding the defective Moka plant one matter of concern is the possibility of insect transfer of pathogens in the raw sewage to homes of individuals in the area. In Laventille it must be obvious to the Ministry of Health that in unscreened pit latrines there is the risk, if not high probability, that exposed water and food will be contaminated with pathogens.

The Laventille problem as projected in a recent Express lifestyle feature on the other hand must surely be inexcusable and unacceptable to all past and present administrations, given the obvious density of the population in the immediate area of the row of pit latrines.

In part the problem may be related to our political culture where in the past few years there has been a trend in infrastructural development toward a highly unbalanced concentration on the glossy and costly in so many different fields — the hotels, high rises, stadia and performing arts centres.

Even the basic service facilities of hospitals, schools and roads appear to get priority over basic waste-handling facilities.

With our population density, and our aspirations towards developed country status, it appears that a national sewerage system seems to have been given relatively low priority. It is not seen and therefore there is not much political glamour to it.

One might hope some lessons may have been learnt from the past. The Sea Lots treatment plant of the Lockjoint era of a few decades ago, rather like the Moka plant, fell into decay largely for lack of maintenance and was abandoned and fully replaced with an entirely new processing system which we must assume is regularly maintained.

Curiously its outlet water which is of extremely high quality, better than Caroni River water, simply flows into the Gulf of Paria! Why?

• Julian Kenny, chairman of the Environmental Management Authority, is a biologist and natural history author. He is a former UWI Professor of Zoology and

Independent senator