The Roll of Lime Dosing in Water & Sewage Treatment


Lime Dosing

Lime Dosing is an important process that involves the treatment of Human Waste. Lime is added to sewage via the use of conveyor and mixed with sewage to kill dangerous bacteria such as e.coli. The mixture of quicklime to sewage is an exothermic reaction and it is the resulting heat that causes the bacteria to die. The bacteria is killed as the increase in temperature cause the three dimensional tertiary structure of the fundamental for life active sites in the bacteria. It is not the sewage that reacts with the quick lime, calcium oxide, but rather water, the most commonly found liquid on the planet.

The Process

The process requires a homogeneous mixture as it causes the quicklime to moisten through its exposure to the moisture in the sewage sludge. The reaction can also cause the pH to change. The pH becomes more alkaline as it reaches a max of 12. Lime treatment is hugely advantageous as it can reduce pathogen count by 6 log. Another advantage is that the sludge is stabilised and is not suitable for the regrowth o pathogens. When the process is over the environment is not suitable for any pathogens to live or multiply. The odour is also eliminated by the process this means the vector attraction is massively reduced. The cost of using lime is relatively low compared to the cost of electricity or gas. Lime dosing is a very simple process that doesn’t require a lot of work from the designing engineers. The plant is also fairly repeatable so once built, similar plants can be installed in other, different areas.

The Sewage Treatment Process


EU regulations make lime dosing a very important part of the UK and, in turn, EU waste treatment system. The EU has strict laws directing on how pathogens should be eradicated from treated human waste. The end product produced is rich in organic matter and easy to spread due to the dry solids content. The EU states that human waste must have been prescribed to advanced treatment a process which is easily completed by the lime dosing unit. The Guidelines were agreed between Adas, Water UK, and the retail Consortium. The guidelines have been active since 1999.

Sewage treatment is an important process. Lime Dosing is an efficient way of ensuring all the harmful pathogens are killed. There are other ways of treating sewage but they can be more expensive . Lime dosing also provides a product that can be used on farms or other types of agriculture. The process is also more carbon neutral compared to sewage treatments that use gas or electricity.