Thursday, November 22, 2007

Litani again

An article sent to me by Bech on the pollution of the Litani river and the dangers posed by the use of its heavily polluted water (little more than raw sewage discharge). While the article adresses a number of real issues, it tends to over state the danger due to the use of wastewater in irrigation. Treated (even just at secondary level) wastewater effluent is a potential source of irrigation water we should not dismiss. But the Litani water in summer and fall can really be foul, I have blogged on this topic here (effect of pollution) and here. A couple of points here:

1. The section of the Litani river addressed in the article is that close to the sources, before it meets the Berdawni (another sewage outlet) and before it crosses the Zahleh industrial area (where it gets even more polluted, this time with nasty stuff) and before it crosses the west Bekaa (more discharge, especially from the sugar beet factory and from domestic sewage). The real picture is probably worse. There has been a number of studies on the Litani water quality, for some reason, it is a favorite with USAID and other foreign donors. There is in Lebanon a special body vested with the management of the Litani, aptly named the Litani Water Authority. Just google Litani river authority to know more about it and about the results of the monitoring of the water quality. One of the problems with the projects is that they often only monitor for a short period of time and make generalizations. another problem is that their results are often contradictory.

2. The problems of irrigating with wastewater or even with raw sewage are most relevant when dealing with vegetables eaten raw. There are clear guidelines on the use grey water or even raw sewage for irrigation. Check these for instance, you will see that most of the problem is with microbial contamination. Especially when dealing with diluted domestic sewage (polluted water) and with tree crops, the problem is not as dramatic as with vegetables eaten raw. Most of the problem is microbial contamination of the external surface of the crop and danger to workers. Not that this is a small thing mind you, look at this study: "According to the authors’ estimates, the annual risk of contracting infectious diseases including typhoid fever, rotavirus infection, cholera and hepatitis A from eating raw vegetables irrigated with untreated wastewater is in the range of 1.5 × 10-1 to 5 × 10-2, or 5–15% of consumers eating such vegetables will develop a case of disease compared to 10-6 (0.0001%) of those eating vegetables irrigated with treated wastewater effluent that meets the WHO guideline of 1000 faecal coliforms (FC)/100 ml." Remember also that China's agricultural revolution grew from night soil.

3. A tiny little funny info: The author quotes someone saying that the sewage is used for irrigation in the village of Ksarnaba. This is where most of the damascus roses (Rosa damascena, ward jouri) are planted in Lebanon, and then distilled to make the best, most pungent rose water, used in sweets and in perfumes and as a skin remedy. Just thought I'd let you know.


bech said...

So just to recap. today in lebanon there is absolutely no treatment of either the sewage wastes or the waters where they are dumped?

Rami Zurayk said...

yep along the coast, everything is dumped into the sea. Inland, it is dumped in wadis, in irrigation canals (the famous waterfalls from Bsharreh to Wadi Annoubine are mostly sewage in the summer and fall), or in holes in the grounds (jura su77ieh) which is often connected to the spring in the village below because of the fissured limestone that makes up most of Lebanon. Ever wondered why the water from 3ain el dai3a tasted so good? A recent research found a majority of them to be contaminated with fecal coliform. Guess who's the greatest beneficiary? The bottled water industry, of course.