Frequently Asked Questions - Dewatering Solutions Inc

1. How long will it take before the sludge is dry enough to haul off?
2. How do I determine how many Geotextile tube containers I need for my plant or my project?
3. What happens if I fill the Geotextile container higher than the design height?
4. Can I dewater municipal wastewater treatment biosolids without using polymer?
5. Can Geotextile technology dewater and contain secondary sludge?
6. Can Geotextile technology dewater and contain primary sludge?
7. What is the main reason to use Geotextile technology?
8. Can Geotextile containers contain contaminated material such as PCBs?
9. How do I find out if Geotextile containers are right for our needs?
10. Can Geotextile tubes dewater and contain Alum sludge?
11. Can Geotextile containers dewater and contain fly ash?

How long will it take before the sludge is dry enough to haul off?

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There are several factors that influence the time it takes to sufficiently dewater sludge:

1. Chemical conditioning is the key to optimum dewatering. Working with a polymer supplier, bench tests are conducted to determine the best polymer for dewatering the sludge. Once the product is chosen, the dose is determined. Overdosing the polymer can cause the sludge to “hold onto” the water rather than releasing it and may result in blinding off the Geotextile Tube. Properly mixing the polymer into the sludge is also important. The polymer should be made down into a lower percentage solution and ideally, aged for 30 minutes before injecting it into the sludge line. Equally important is to provide enough mixing in-line to assure that the polymer attaches to the sludge particles to create a floc and allow the free water to flow out of the Geotextile containers.
2. Type of sludge or age of sludge can influence how fast it will dewater. Well digested sludge will dewater more quickly than raw sludge. As process water sludge will dry faster than biosolids.
3. The longer a client can allow the sludge to remain on site and dry after the final filling cycle, the drier the solids will become and the greater volume reduction will be achieved.

How do I determine how many Geotextile Tubes I need for my plant or my project?

First we gather the following information:

• Volume of sludge or flow rate of residuals to be dewatered.
• Specific gravity of the solids.
• In situ percent solids.
• Percent solids during dredging or pumping.
• Target percent solids after dewatering.
• Production rates, GPM, hours per day and efficiency of pumping or dredging.
• We begin by doing bench tests to determine the appropriate chemical conditioning. Tests are then conducted to determine volume reduction and target cake solids after dewatering with Geotextile tubes. The tests may be a Bench Dewatering Test, a icy bag test, a full-scale test or a combination of two or more of these tests. Samples of dewatered sludge are taken at intervals and dried to determine percent solids by weight.
• This information is put into a spreadsheet designed to determine the linear footage of various circumference Geotextile containers required to accommodate the volume of sludge.

What happens if I fill the Geotextile Tubes higher than the design height?

Geotextile tube design height is controlled by the tensile strength of the textile with a 4:1 factor of safety. Exceeding the design height could result in the textile rupturing.

Can I dewater municipal wastewater treatment biosolids without using polymer?

Yes, but the capture of solids won’t be as efficient and it will take much longer to get sufficiently dry cake solids. There is also a risk of masking off the pores of the textile. We recommend the use of polymer on most sludges.

Can Geotextiles dewater and contain secondary sludge?

Yes, It will probably require a polymer to assist in flocculation. This will result in very clean filtrate and solids comparable to older mechanical dewatering technology.

Can Geotextiles dewater and contain primary sludge?

Yes, most installations use a polymer to assist in dewatering allowing faster refilling and obtaining finished solids sooner. Solids levels are usually equal or higher than the traditional older mechanical methods.

What is the main reason to use Geotextile tubes?

Economic savings have been realized by every customer using Geotextile Dewatering systems over traditional dewatering, remediation processes.

Can Geotextile Tubes contain contaminated material such as PCBs?

Yes, Geotextile Tube Dewatering has been chosen by both governmental agencies and private companies as the leading way to safely contain most contaminants, especially PCBs. Geotextiles also provide the added protection of aerating contaminants when processed through an older technology of mechanical methods. Economic reasons are again a key factor.

With competitive price and timely delivery, PENNPLAN sincerely hope to be your supplier and partner.

How do I find out if Geotextile Dewatering is right for our needs?

Contact a DSI representative to discuss your goals and objectives. Experiences with similar applications may already exist that can answer your questions. If not, we normally start with a bench trial to determine if there is a good chance of success. Then a trial can be performed using about 40 to 50 gallons of the material for each bag to help provide estimated chemical needs, dewatering rates, filtrate concentrations, etc. In a few applications a full size Geotextile Tube is installed as a pilot study.

Can Geotextiles dewater and contain Alum sludge?

Yes, It will probably require a polymer to assist in flocculation. This will result in very clean filtrate and solids comparable to older mechanical dewatering technology.

 Filling of soil: The moist soil to be dewatered is first filled inside the geobag. The filling should be evenly distributed to avoid overly dense or loose conditions.

Drainage: After the filling is completed, the drainage process begins. Geobags are usually permeable, allowing water to drain out of the soil through the pores of the bag.

Compaction: To accelerate the dewatering process and improve soil consolidation, moderate compaction can be applied during the soil filling and drainage process. Light compaction can be done with specialized equipment or by hand to compact the soil.

Waiting for dewatering: After drainage and compaction are completed, the geobag needs to be given enough time to dewater. Dewatering time will vary depending on soil moisture, ambient temperature and other factors. It usually takes from a few days to a few weeks.

Removing Cured Soil: When the dewatering process is complete, the cured soil can be removed from the geobag. The cured soil will become drier and stronger and can be used for subsequent project use.

It is important to note that the dewatering process of geobags should avoid exceeding the maximum carrying capacity of the bag to avoid damage to the bag. In addition, the dewatering process also needs to pay attention to the effect of drainage and the degree of solidification of the soil to ensure that the desired effect is achieved.

Are you interested in learning more about geobag dewatering? Contact us today to secure an expert consultation!