Tank Cleaning

When should a digester be cleaned?

There is no set formula for digester cleaning.  Typically a digester should be cleaned before a significant drop in treatment efficiency is noticed. This will depend on a number of factors including plant headworks, plant volumes, and influent characteristics. As a rule of thumb, many plants are cleaning their digester tanks every 4-7 years.

Who should clean your tank?

Do not attempt to clean a tank unless you have had confined space training as hazardous gases may be present.

Most tanks are hazardous environments, and entry may lead to severe injury or death. Regardless of tank size or purpose each tank will need to be cleaned by a qualified professional.

 

How do you clean digesters?

Digester cleaning requires the removal of heavy material (ie:  the scum blanket and heavy build up) from the digester.  This material can be pumped out with hydraulic pumps or vacuumed out with high powered vacuum trucks. The material can then be either handled as a liquid or dewatered to a semi-solid. In either case various factors will have to be considered before a digester is cleaned, as each option has pros and cons which will change depending on your plant location and process. Wessuc Inc. primarily uses vacuum trucks for digester cleaning and has develop specialized equipment, such as our mobile screening unit, for our digester clean out projects.

Why should digesters be cleaned?

Digesters, like other tanks, need to be cleaned on a regular basis to ensure optimal performance.

Despite advancements in mixing equipment technology, all digesters sooner or later build up a bottom deposit of sand grit and heavy solids of all descriptions. Additionally, most digesters form a scum blanket on the top of the digester. Both the build up on the bottom of the tank and the scum blanket reduce the digesters effective treatment capacity and lead to short circuiting or reduced efficiency.

What is a digester?

A digester is a tank designed for the biological treatment of organic matter.

The tank is designed to provide control of pertinent operation and environmental variables. The operation and environmenal variables are controlled so that treatment can occur at accelerated rates. Although there are various methods of digestion, all have a common goal of stabilizing the sludges they receive.

Why clean tanks?

Most tanks need to be cleaned for one of two reasons:

1) Improve tank function or efficiency
2) Enable regular maintenance/inspection to be completed on the tank

Tank cleaning is becoming increasingly important for optimal wastewater and water treatment plant performance.

When are tanks cleaned?

Most waste water treatment plants have a regular schedule for their tank cleaning based on historical records and present tank efficiency monitoring.

However often tanks are cleaned for emergency repairs or for inspection purposes. Small tanks such as septic tanks will need to be cleaned on a regular basis depending on the loading they receive. Each case is unique to the function of the tank and other components of the plant or process. Contact us to help you develop a cleanout schedule.

When should wastewater pumping station wet wells be cleaned?

Solids, grit, sand and debris remain suspended in the wastewater as a result of the high flow velocity and the mixing actions of the liquid.  When the wastewater enters wastewater pumping station wet wells the velocity of flow and the mixing actions are reduced, allowing these solid materials to settle out. If the pumping station wet wells are not cleaned out on a regular basis, this debris can build up causing excessive wear on mechanical equipment, and can also plug pumps and cause system failures.  The cleaning of wet wells is dictated by many variables, but an annual cleaning program is suggested to maintain optimum performance in the pumping station.