Water and Waste

s diverse product range has helped with a variety of applications in the water and waste sector, including:

  • Foam level monitoring and control
  • Sludge blanket level monitoring
  • Liquid level control
  • Silo protection for lime powders
  • Pump control

 

Application: Silo Protection for Lime Silos

Powdered lime is utilised extensively in the treatment of wastewater; for example, to reduce odour in raw, primary sludge, as a cost-effective alternative to using digesters. It is also used in other water treatment processes to help balance pH levels and as part of composting methods for sludge removed from the bottom of primary tanks after it has been de-watered and compressed. The lime and remaining water in the sludge together creates a heated chemical reaction, accelerating the process.

As with most other vessels storing powdered products, lime silos are susceptible to over-pressurisation arising from filtration blockages or excessive input pressures from delivery tankers. Silo over-pressurisation will result in a multitude of problems for sites:

  • Powder escaping the vessel into the environment (particularly problematic as lime is corrosive)
  • Damage to equipment and potential buckling of the silo
  • The potential for silo rupture or the filter unit to be blown off the roof by pressure build-up

These issues are common across many industries. Fitting silos with comprehensive pressure protection systems will negate these problems. These systems monitor and control pressure in a silo during deliveries, stopping filling if there is a problem and indicating what maintenance work is needed to keep the site safe. You can find out more on our silo protection FAQ page HERE

Application: Foam in Municipal Waste

Evidence shows that Sewage Treatment Works (STWs) have almost continuous issues with foam, including in digesters, activated sludge plants and centrifuges. Controlling this has traditionally required many tons of antifoam chemical every year, which can become very expensive. Also, foam can cause costly damage due to blocking filters and causing over-pressurisation, as well as damaging gas compressor blades. It is not unheard of for the roof of a digester to be pushed off by excess foam, resulting in repair costs that run into millions of pounds.

Bulking sludge and foam are two undesirable, complicated and unpredictable challenges for many treatment plants. In many cases, the filaments and filamentous bacteria (commonly Nocardia or Gordonia) causing bulking sludge tend to float and thereby produce vast amounts of foam. The foam may vary in depth considerably and extend throughout the biological circuit, as well as to anaerobic digesters and de-watering units.

The traditional approach is to dose antifoam into the process continually. Typically, this dose rate setting is based on the plant's peak demand, when foam production is at it's greatest. However, on average, this is far too high, and in some systems, there is little or no foam generation for most of the time. Alternatively, the addition of chemicals is often done randomly, in far too large quantities and too late. This reactive approach results in minimal control and understanding of the entire process.

In some cases, the WWTP can suffer for years without finding a sustainable solution to the problem. These chemicals themselves may also add to the foaming problem. In both cases, the high cost of chemicals and energy through unnecessary pumping can be substantial. Unnecessary equipment wear and damage will also generate additional expenses. The use of foam monitoring and control technology is poised to have a significant impact on the industry.

Application: Foam in Industrial Wastewater

Many industrial processes involve cleaning water before discharging it to the local sewer. Treatment may include removing solids and heavy metals and adjusting pH balances. The clean-up processes often involve air injection, for example, DAF, activated sludge and flocculation, which can cause the foam to develop in dirty water. The nature of the materials in such effluent varies, as will the tendency to foam. By detecting when the foam has reached a critical level and dosing antifoam, the process can be controlled at a minimum of cost, which is far more efficient than previous automatic dosing methods.

Hycontrol has specifically developed highly versatile foam control systems for measuring the thickness of the foam in a process, detecting foam-liquid interfaces and measuring liquid levels, ignoring the presence of any foam. The patented technology behind these systems originated from detailed research into foam control during pharmaceutical fermentation. Hycontrol points out that the unique measuring sensors and control equipment have been designed specifically for foam control and are not modified level sensors. 

 

Prominent Hycontrol customers in the water and wastewater sector include Severn Trent, Anglian Water Dublin Bay, United Utilities, Scottish Water and Southern Water. To discuss your application in this industry, please contact Hycontrol via the methods listed below.

Understanding and Controlling Foam in Industry - White Paper
Bringing Anaerobic Digester Foam Under Control - White Paper
Municipal Waste Water Foaming Application - WWT
Multi-Point Level Monitoring Application - Waste Processor
Accurate Dam Level Measurement Application - ENDESA Chile
Sonarflex Effective Sludge Monitoring Application - Waste Water Treatment Works
Foam Control in Municipal Waste Water Treatment Overview - Southern Water

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