Sludge recycling

[Yankybrit]

I am looking for a method to benifically recycle WWTP sludge. We currently produce about 1000 tons per annum and the material is non hazardous with about 70% water content with Iron being the next major constituent at about 10% and Calcium at about 3%.

I am looking for any methods to recycle the material as is and any methods that would require some process changes that would make the make the matterial more recyclable, such as drying or change to alumu instead of ferric.

Any suggestions?

 

[RWF7437]

Both the City of Milwaukee WI and Salem OR recycling their sludge as fertilizer for crops NOT for human consumption. The build up of heavy metals in the soils limits the usefulness of the sludge as do some other factors. You might try contacting them and reviewing what they do.

Russ Faust
Salem, OR

 

[KRSServices]

We utilized our WWTP sludge and applied it to pasture fields (horses). The animals were not allowed to graze until 6 months after injection.

It was the greenest field for miles around and of course, it had approvals from regulators. KRS Services

http://www.krs-services.com

 

[ischgl99]

Ferric and Alum are not the best when if comes to land applying. To get the most benefit, you want to precipitate out the phosphorus in a useful form to increase the fertilizer value of the sludge. Brucitic marble and magnesuim hydroxide are used for sludge conditioning, odor control, nitrification, phosphate precip, reduction of polymer, etc. That will improve your process as well as make it desirable for land application. Mike Bensema

http://www.dutchmenservices.com

 

[Yankybrit]

Thank you for your response about landspreading. This is an Industrial process and does contain a low level of heavy metals. Can you refer me to guidelines for metal contents for landspreading of sludge.

 

[saxon]

yankybrit, Here in Chicago we use land application as the primary disposal method or as secondary, fill. Annual volume is in the neighborhood of x million tpy. In fact, the sludge farm (for leaching/drying purposes) has got its own railroad.
The main issue's of this type of disposal are uptake and bio-accumulation in the food chain or storm water runoff to the surface waters. Hence, strigent regulations regarding concentrations of toxic heavy metals and organics (beyond the regulated limits this stuff becomes a hazardous waste and must be handled as such, with incredible operating cost consequences). Check with your local Environmental office, they are familiar with all of the pertinent regulations and requirements and applicable permits required.

Hope this helps,
saxon

 

[waterexpert]

The japanese are using biological treatment sludge for all sorts of stuff, making building materials by mixing it with PFA from power stations.

 

[sommerfj]

Another option is to pelletize the sludge and sell or give it away as a landscape/lawn fertilizer. I understand that one brand has been made for years from Millwaukee municipal sludge. Chicago, Toronto, and Atlanta are either doing this with part of their sludge or building plants to do this. You might want to ask them.

 

[kenvlach]

Re use as fertilizer: More detailed analyses are needed to determine feasibility. Besides the heavy metals, you have to be concerned about certain neutralization salts. E.g., chlorides are bad, whereas sulfates, nitrates and phosphates are okay in limited amounts (provided that runoff to surface or groundwater is limited – often a function of the weather!). In any case, (as others have mentioned) you will need justifying analyses and plan approval from your EPA-administering agency. A land disposal plan needs soil type, permeability, depth to groundwater, climatic data, slurry storage methods, etc.

Re slurry vs. solids as fertilizer: The Metropolitan Milwaukee Sewerage District has for many years used biogas to generate electricity & heat. At their main plant (Jones Island), some of the heat has been used since 1926 to dry & sterilize & pelletize treatment product sold as the fertilizer 'Milorganite.' I believe that removing the water is not energy-efficient -– it only makes for convenience in spreading granular fertilizer on lawns.

At the newer MMSD South Shore plant, biogas is burned to provide electricity for the plant. The treated effluent in slurry form is used as ‘Agri-Life’ fertilizer, which is then spread from 6000 gallon tanker trucks. Below is a link to the Metropolitan Milwaukee Sewerage District:

http://www.mmsd.com/about/page6.asp#Agri-Life

You haven’t mentioned the wastewater source, but some modifications may make the sludge more suitable/safer to use as fertilizer. You should also consider alternatives. Perhaps you are pickling steel and your waste contains heavy metals Cr, Cu, Ni and Zn. You might consider an acid purification unit from some company like Eco-Tec or US Filter. This would give a small amount of more concentrated waste to send to a metals recovery company (Encycle, US Filter, World Resources, etc.).

 

[iski]

Here in the Philippines, a paper processing plant has used its sludge from the wastewater treatment plant as a component of concrete hollow blocks (CHBs) and cement board panels. In fact, the company exhibits a model low-cost house made of these materials. The sale of the CHBs, which have lower costs than the commercial ones but within standard strengths, is doing quite well. The cement panel boards are their new product and sales are also starting to pick-up.

hope this helps.

iski

 

[oxilume]

Yankybrit,

My company has recently developed a patent pending cost effective sludge dryer. Units will be available for rent in late July. The rental and drying costs are offset by reduced transportation costs and an efficiency increase in your current WWTP operations.

I can email a brochure to you. Please email me at:
toddforet@usa.net

Sincerely,
Todd Foret