Sludge Disposal

Follow local codes and practices.

Good to hear that you are concerned about pollution as this the most ignored area in India.

But I doubt that any one will suggest you " what to do" as it falls in area of statutory requirements and should be only done with in the guidelines of statutory body.so if you can list down those guidelines and come up with the specific questions about the achieving your objective probably members will help you in better way.

But I have a bigger question also, to the best of my understanding it is mandatory to have the disposition set up in existence before unit start working, So how come your unit is working with out such facility?

BTW, is this govt owned or private owned?

<...it is mandatory to have the disposition set up in existence before unit start working, So how come....unit is working without such facility?....>

That's an excellent question!

Actually answer to that question lies in the answer of the next question I have asked.

Nope. That's far too subtle. Please explain.

Discussing Governments and politics prohibited on CR4.

Ah! Just subtle enough. Thanks!

Yah, i agree with you PWSlack.The disposal of such sludge should have been mitigated by the Environment Impact Assessment already before the implementation or construction of such facility as SOP. to get a Environment Compliance Certificate at construction phase and operation.

Well, you can use the sludge anyway as a fertilizer to farms.

"Well, you can use the sludge anyway as a fertilizer to farms"

NOT ON MY FARM YOU'RE NOT!!!!

I work in the industry and until I know what else has been added to stabilise and cause the impurities to settle I would not accept it. Yes there are heaps of nutrients in there, but probably high levels of Aluminium and a few other "nasties".

Comply with permit requirements.

Without knowing the specifics, I can only suggest one possibility that may or may not be appropriate for your situation. But you may want to consider using an industrial filter press. Perhaps renting one. If you are unfamiliar with them... they are composed of a series of square flat plates that are concave on both faces. These plates are stacked next to each other, like books on a shelf. I have seen them as large as 12' x 12' in size, about 8" thick. There are also smaller sizes. They are pressed together with hydraulics, within a large frame. Commonly, there can be ten to thirty of the plates side by side. The concave surfaces result in pillow shaped empty spaces between each plate.

The sludge is pumped thru this horizontal stack of plates, is filtered as it goes thru, and what remains between the plates is only the solids. This is then internally heated and dried. When the plates are separated, what remains is solid bone-dry cakes comprised of all the solids. These can then be disposed of in a variety of ways, depending on what the sludge was made of. It is much easier to handle the dried waste in this manner.

I've seen similar to what you describe used in the wine industry and they are wonderful for that sort of applicaiton with relatively low contaminant levels.

The water treatment plant that is described though is four times larger than the one that I deal with. We use a centrifuge to concentrate the material from the bottom of our clarifier tanks and achieve around 20 cubic m per week (including polymers added to bind the unwanted material).

I imagine that he has two tanks, approx 30m diameter with sludge that has density around 1.001 relative to the water (doesn't settle easily) and a typical particle size around 10 micron including organic materials like algae. The clear water flows off the top and the concentrated sludge is steadily withdrawn from the bottom for further concentration.

Using "in line" filters for this application requires significant energy to run the pumps for the differential pressures that develop as the filters fill.

There are also "disk" filters that enable a continuous process, but the particle size limits their suitability.

I would be interested to find out from them what separation/concentration process they currently use, since that will provide insight into appropriate disposal methods.

Heck, it might even be appropriate (if they are using river extraction at less than 1% flow) to return the concentrate to the river, and hence the nutrients and all else return to the natural water cycle.

If the constituent contaminants are not an issue with the regulating agency, then you may want to investigate a non-energy intensive alternate (although I tend to like filtration plates in a larger treatment plant to reduce the water content).

Look into sludge drying beds. Due to your location there in India, you have plenty of solar radiation to help you in your efforts to dry the partially de-watered sludge cake, so use all of it that you can to help in your Unit Processes! I strongly suggest that you cover the drying beds (and underdrains) with roof so that you don't have flooded drying beds during the Monsoon season.

The USEPA has some terrific sludge drying bed designs that are simple and inexpensive....check out their website. Also, Metcalf & Eddy's classic textbook Wastewater Collection, treatment and disposal in a great resource and is found online for free download as an E-book.

If you go the sludge drying bed route, make sure that your filtrate lines (underdrains buried under a sand bed) discharge to a leachate pond or series of ponds of significant size. These ponds will have to be engineered and may require a discharge permit if they convey wastewater to a receiving body.

Just a few Cents tossed onto the Poker Table....

Good luck with your project!

==Signed,

CaptMoosie, PE/PhD

Civil, Structural, and Environmental Engineer

What is the sludge composed of?Any harmful leach able item? What is the moisture content ? What is the method of separation of sludge? You have mention Water treatment plant ! Is it that or Effluent Treatment plant. More details are needed. Depending on sludge quality and quantity, various options are there to process at factory to minimize total cost. Then comes safe storage /disposal.

Details of contents of sludge is very important for its safe disposal. Please refer the local environmental and pollution codes and standards before its disposal.

Water shall pass through flocculation-coagulation process using lime (10 ppm dosing) and alum (60 ppm dosing) and thus sludg shall be loaded with lime -alum molecules which exibits decaying property.Plant is still under construction phase.If we go for construcing drying bed than too problem remains the same as process of drying sludge will only remove water contents and disposing the cakes environmentally will again be the problem. "Back to square one".We know that this sludge can not be uaed as manuare/fuel as against dried cakes of sewer treatment plant.

Have you done any laboratory analysis with Water (?) and check what is the sludge? With 10ppm lime and 60ppm alum , you will hardly get any sludge. First find characteristics of sludge and then think of solution. Actually this should have been done before you ordered the treatment plant. The sludge handling/drying/disposal can be done by various methods, but the input product details are needed. even an estimate will do.

A high-shear annular crossflow filter (e.g. McCutchen U.S. Pat. No. 7,757,866 (2010) pending in India) might be worth a look. You need something that will, in a continuous (not batch) process, dewater the sludge and thicken it into a paste to make it easier to get rid of, preferably avoiding dead-end filters and added chemicals. Dumping the wastewater on crops does not sound good, and as others point out, during the monsoon its utility would be dubious.