Reducing the Sludge Disposal Costs

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Reducing the Sludge Disposal Costs

How do you deal with high costs of sludge disposal?

I am interested to hear which methods and technologies you use. Furthermore, I would like to know about the changes you made that have reduced your costs.

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10 Answers

  1. How do you handle sewage sludge, organic sludge, chemical sludge, etc.? 

    Generally, 1st Mechanical dehydrate such as Beltpress, Decanter, Filterpress, Thickener equipment, The Cake sludge of water content will be about 70~80%wt. However, 'cell water' in Floc can not be dehydrated by Mechnical physical dehydration equipment. 2nd, To dehydrate or dry 'cell water', Most of User are dried by hot air, solar dry, such as Solar Dry, Belt dry, Drum Dry, Fluid Bed Dry, or sent to the incinerator for burnt with high heat energy or landfill. But these kinds of method are having a lot of problem as;

    initial investment is very high

    difficult to operate.

    contamination occurs

    costs are also high...etc.. 

    You can choose ELODE to solve all these problem at once, which is a breakthrough dewatering (drying) method of ELODE(electro-Osmosis dewatering equipment). Only operate at 1/3 of your current processing cost, and the initial investment is very cheap, so you can recover it within the maximum 2 years.

  2. If you want to reduce costs, then you should move away from mechanical methods. Mechanical systems can be effective, but at the same time they have high operational costs (use of chemicals, high power consumption, needs for specialized staff) and high maintenance needs. I have been working since many years on a green technology for sludge dewatering and drying; sludge treatment wetlands. In these systems, sludge dewatering takes place through natural processes only mediated by the presence of reeds, no use of chemicals is required, while power is only consumed for the distribution of sludge on the bed surface. It can even run without a permanent staff; regular inspection of the facility is adequate eg every 2-3 weeks. You have continuous loadings with sludge for many years, without the need to transport the dry solids on a daily basis to a landfill for final disposal. After few years of operation, the residual sludge layer that is built within the system is removed and then a new loading cycle beginns. The removed biosolids are digested material and they can be reuse eg in agriculture. The main concern with these systems is that they require higher land than mechanical systems. But they provide many benefits, both financial and technical, while the use of a green technology such as sludge treatment wetland promotes sustainability and the green corporate profile.

  3. Our customers try to reduce by optimal use of polymers to reduce water content of the sludge. Regular testing of dewatering caracteristics is than necessary. The option to use sludge as feedstock for worms is also interesting, but I do not know the economics of this solution.

    1 Comment

    1. Roemer Goossensen The economics are very favourable, with very little power required, it is an aerobic process (with the worms natural burrowing activity providing the aeration for the system). An example (quality wise) a humus sludge from a percolating filter (~1.5% dry solids) as the input would produce an effluent 200 - 300mg/l BOD.  Overall solids to be disposed of would reduce by ~80%, but it would be a solids material ~70 - 80% dry solids - very easy to handle and transport.  N,P & K levels would be determined by the levels within the feed stock.

  5. One method that has worked effectively here in Colorado is non-amended composting. The weather here is mostly dry. For a small facility, an operator only needs a Bob Cat to turn the sludge over every few days. The sludge volume greatly reduces. Some facilities then market the sludge to local businesses as a soil amendment and then sold to the public. The wastewater facility can then earn some revenue from this, thereby, cutting down there sludge disposal costs. Other facilities may store the sludge on site and have the general public come in once to several times per year and take the compost off site. This too greatly reduces the facility's sludge hauling costs.

  6. Having been a sludge process scientist some years ago I have always kept a keen eye on sludge tech as conventional wastewater treatment produces endless quantities of the stuff.  The basic rule of thumb is the more you treat wastewater then the more sludge you produce, giving you an even bigger headache in dealing with it.  Like everything in wastewater the options available are dependent what restrictions are placed on the Company by legislation, how much money you have available to spend and what (if any) your target market is for the end product.  

    Here in the UK if you want to use the sludge as a product suitable for agriculture, then you must treat it to a high standard by reducing pathogens.  The US has a similar scheme.  Keeping pathogens down mean that only certain technology can deliver this outcome.  Anaerobic digestion  provides a lower quality product which (in general) needs to be dewatered before application, but the rush for feed in tariffs have made this technology very popular.  To reduce the pathogen numbers more then you can go for cambi technology (a pressure cooker type technology), sludge drying, but with experience this technology has receded greatly from what was seen as the "ultimate solution".  Less capital intensive technology are the lime technologies, which requires less capital expenditure, but is expensive to run and a right pain H&S wise from using quick lime.  I would add that when deciding on what sludge technology you want you must factor in how to treat the liquids that will in inevitably come from the system.  Solids capture and treatment always leave what can be a high strength liquid stream that can play havoc with your WWTW unless this side stream has been factored in.  

    Contrary to all this technology should you have warm temperatures and endless sunshine then the cheap and simple solution is to use sludge drying beds. Dried sludge has the equivalent calorific value as brown coal so you could burn the dried sludge.  No idea what this smells like though!  You can also use dewatering tubes, where you put the liquid sludge in, the membrane allows water to escape and you are left with the solid residues.

    As an alternative to all of the above our Sludge Wizard (SW) is a biological treatment system which uses worms to treat liquid sewage sludge.  Low capital and running costs, the SW treats the sludge effectively and efficiently.  The resulting effluent waste stream has  BOD levels similar to that of domestic sewage, so it does not impact on the WWTW unlike conventional technologies   The resulting solid by-product (worm casts) makes for an ideal alternative to chemical fertiliser and has higher N, P & K levels way ahead if you just used conventional sludge treatment technology.

    As an aside sludge disposal implies that you are just getting rid of it at lowest cost with the sludge having no value.  Sludge recycling (to agriculture) is attributing a value which can deliver benefits.  In agricultural terms it is recycling nutrient N, P & K and organics which are vital to plant growth.

  7. I use the green technology of Sludge Treatment Wetlands. It is based on plants, with minimum mechanical equipment, without the use of chemicals and with no need for specialized staff. The main advantages are the very low operation costs (up to 90% reduced compared to mechanical methods) dur to the minimum energy consumption. There is no need for daily/weekly transport of sludge. Sludge is accumulated and dewatered-stabilized in the reed bed for 6-8 years. After that time, residual sludge layer is well stabilzied and is removed to be used as fertilizer, for example, since it is a valuable biosolid material. So, I think that these systems are ideal to reduced your total costs and also apply an environmentally friendly technology.

  8. Effective dewatering by mechanical means can be followed by a variety of treatment options. The dewatered sludge can be used as fuel in a biomass gasification system, can be fed to Black Soldier Fly larvae to produce feed, can be composted, or even used to produce methane prior to dewatering.

  9. I have seen tremendous success at dewatering by the use of Colloidal Silica in the Paper production  Industry.    It is quite inexpensive and works very well.  

    Further, depending on the HRT of the WWTP process, utilizing Microbes to reduce the amount of Sludge is very successful.  The successful process utilizes aerobic microbes witch converts all organics to Carbon Dioxide and Water.  The only resultant sludge is inorganics which are a minor part of the original sludge.  Obviously,  this works even better in WWTP processes which are utilizing lagoons. The process can even increase the capacity abilibty greatly.  This can be used instead of the very expensive upgrading of the facility to increase the plant's capacity

    1 Comment

    1. Why stop at microbes?  We have developed a system that uses worms (tiger worms or Eisenia fetida) to treat sludge produced by conventional biological treatment.   Liquid sludge is fed into the plant and the worms within it (~10,000/m2) feast on the solids.  The resulting effluent has a loading characteristic similar to domestic sewage, which makes it to very easy to treat.  In short a system which significantly reduces sludge treatment costs, removing the need for complex dewatering systems, tankers and the high on-costs for disposal. PM me for more details.

  10. Sounds simple, but reducing sludge disposal costs can come from reducing the amount of sludge. This is done through dewatering, different treatment methods which minimise the amount of sludge - e.g. avoidance of alum, and then finally identify secondary life for the sludge - soil conditioners, fuels etc. To do this you may also need to change the treatment method. 

    1 Comment

    1. Dewatering takes a huge amount of energy and the huge pumps are difficult and expensive to repair.  Further, you have to pay for trucking fees and tipping fees to ship the sludge.  Many states do not allow this sludge to be used for putting on land as fertilizer due to possibilities of unfriendly ingredients in the sludge and lastly, you are responsible for the sludge should the truck have an accident...the sludge is your responsibility until it has reached its final home.