hi all,
I am looking for the best practicing of drying the digested sludge in beds using solar energy only, as we have strong sun throughout the year .

Decades ago, when I actually worked in municipal sewage treatment, we had large drying beds.  The plant was located in Southern California, which receives an average of 13 to 15 inches of rainfall per year, essentially all during the months of October through April.

We dosed the digested sludge with polymer, which allowed for separation of the solids and a clarified subnatant, which was drained back to the headworks through wooden dockboards.  I would guesstimate that the percent of solids retention was 98-99 percent.

Since we did not have enough beds to handle all of the sludge in a normal static manner we used a large "front-end loader" to "plow and turn-over" the wet sludge so as to expose the wetter portions to the drying air.  That process accelerated the natural drying rate.  We did have problems with flies and odors, as the drying beds were immediately adjacent to a federal customs building.  Hence, complaints from our neighbors.

I would think that if adequate land is available that drying beds are very appropriate in Dubai.

Living in the Middle East will prove invaluable tool for  thermal drying beds.  As the guys have mentioned the draw backs are land requirement (which I would expect to be huge knowing where you are based), along with the issues of flies, odours etc.

To ensure the quickest drying time the best option would be a twin approach of evaporation and as Jeff alluded to, having good underdrain system to collect the water running from the underside of the bed.

Obviously bed depth and temperatures will  have an effect on how quickly it will take to dry, but this will be factored in when designing the sizing of the beds.

take a look at   http://www.parkson.com/Page.aspx?PageID=270&FileName=Drying&CC=true  

Not sure of any installations, but Parkson will sure provide a client list.

Thanks dears

Main goal of the HUBER SRT system is drying of sewage sludge in the glasshouse using the incident solar radiation. A special sludge turning system functions both spreading & turning of the sludge as well as its transportation from one side to the another.