Sewage sludge is a reject from Sewage treatment plants.It is currently used in Bio-gasification and for producing land fill gas ..

 Apart form these uses,can it be used as a direct substitute to fossil fuels?

Sewage sludge contains mostly biological contents ,will a dried sludge provide fuel value?

Any body know references for such works already done?

 Regards,

Kesav

Sewage sludge is widely used as a biomass alternative fuel in cement kilns in Europe.

Best regards

Dr Michael Clark

Dear clark,

      This sewage sludge in particular refers to the reject of a sewage treatmtment plant and not the conventional municipal waste.

Can any 1 tell about the fuel value of it,any help?

Dear Mr.Clark ,

I see that you are an expereiences and an expertise in Cement technology .Can you please tell me How this municipal solid waste is processed and used as a substitue fuel?

How come the odour control is achieved?

Any idea?

Regards,

Kesav

Dear Kesav

Gud luck......................

Can u be more specific on your quiries that will enflighten us to perceive it properly.

rahul

Gross heat value of dry sewage sludge usually lies in the range 8-12 GJ/ton (for a residual moisture of about 10%). It is commonly used in Europe. Due to low heat value, replacement of fossil fuel is limited in main burner.

You also have to take analysis into account. Depending on the origin of the sludge, alkalis, chlorine, sulphur, phosphorus and/or some heavy metals (mercury) may be high enough to become an issue, especially at high level of use.

As for municipal solid waste, the light fraction (sometimes called "fluff") is also commonly used. It is obtained by separation in air-swept drums after coarse shredding. The plastics and papers are carried away by the air stream. They need to be shredded again before use in cement kiln. It is difficult (but not impossible) to get these shredded fine enough for the main burner, so it is preferably used in long residence time calciners. Gross heat value is strongly dependent on moisture content. Chlorine content is a common issue.

 Best regards.

Dear Mr.Ovancantfort,

Thanks for your detailed mail.I infer that you have osme experience in Municipal solid waste processing.Could i have some detailed discussions with you ,if you wish ?

Waiting for your reply.

My id is chemicalenggkesavaraj@yahoomail.com

If you are flexible enough we can chat and have some discussions.

Thanks and Regards,

Kesavaraj

Dear Mr Kesavaraj,

My experience is in fact limited :)  I only visited some waste processing plants producing the fluff we use in our plants. I am not directly involved in this waste preparation. These plants may vary a little but are alway using same principles: shredding, air separation, metal separation,...

 If you do some research on "waste processing" and "RDF" (Refuse Derived Fuel, which is a little bit broader term than "fluff", you should easily find some examples and flow-sheets of such waste processing plants.

 Best regards

Dear Mr.Ovan,

Thanks for your valuable time.You got the crisp and iam in this process of study .If you could help me giving the process flow and suppliers of msw processing ,it will be of great help to me.

 Kindly help me out please if possible......

can you get some details from the plant you have visited?

Could  you please mention me the moisture content of your msw as received?

How much % of the rdf output you get with calorific value above 4000 Kcal?

How much is the power consumption of processing?

Feeding methodology of RDF into the kiln?

How much is the main fuel substitution you get from the rdf feeding ?

My questions are numerous and i think you can answer few.also please mention about urself,that iam interested to know.

I welcome all of you gentlemen to hlep me out if they have such experience  .

Again thanks a lot Ovan

Regards,

Kesavaraj

Like I told you, I am not really in this kind of processing, but it is quite easy to find documents on the Internet. Here is an example of a complete RDF plant involving drying and pelletizing of the RDF: http://www.gec.jp/JSIM_DATA/WASTE/WASTE_2/html/Doc_394.html

The moisture and heat value will depend on the origin of the waste (industrial/municipal) and type of processing (drying, method of separation). What we get in Europe will vary between 2 and 30% moisture for a heat value usually between 5000 and 3000 kcal/kg. Usually, the product from one processing plant will be fairly constant over time.

For introduction to the kiln, we will usually use a bin equipped with a walking floor for storage, followed by a screening device (disc screen or rotary drum) and overband magnet. The transport system to the burner will generally be mechanical (closed belt conveyor), although some pelletized RDF can also be transported pneumatically. You also need a small bin and weightfeeder preferably close to the injection point.

Preferable injection point is in a modern, high retention time calciner. These can accept larger pieces of fuel, up to 5cms. Feeding to main burner would require additional shredding and screening below 1 cm.

A modern plant can achieve more than 60% substitution on RDF (RDF can be fed to more than 80% of the calciner fuel alone)

I think I cannot give you much more information.

Olivier Van Cantfort

Senior process engineer for the HeidelbergCement Group

dear ovan ,

              Many thanks for your valuable reply andd a useful link you have given .

 Absolutely ur answers are crisp and tuned.

Again thank you very much and hope to be in touh with you ..

regards,

Kesavaraj