Effluent treatment

Lime products are also used to treat potentially dangerous and toxic waste and effluent water. The addition of lime often:

• neutralises harmful acids,
• adjusts the pH prior to further treatment or discharge,
• precipitate metals, sulphate and fluoride,
• reduce nutrients (phosphates and nitrogen),
• modify the characteristics of sludge.

In the broadest sense, the use of lime neutralises the often harmful properties contained within waste and effluent water, making them more environmentally friendly and reducing their risk to living organisms and promoting the healthy development of biodiversity and wildlife in the areas where industrial effluent water occurs.

Sewage works

Similar to the treatment of effluents, lime products can also be used to treat sewage that contains suspended solids, dissolved organic matter, nutrients (phosphate and ammonia) and heavy metals.

These have similar advantages to the local environment, such as: the adjustment of the pH, coagulation of the solids and removal of metals and nutrients. However, it is provides a service of disinfection and conditioning of the sludge that can then be used for agriculture or as a landfill.

A wide number of organic and inorganic sludges can be treated using quicklime or dolomitic lime to increase solids content. Biological sludge can be sanitised by the rise in temperature and pH obtained by adding these materials.  Biosolids treatment up Advanced Treated is achievable with this method.

Find out more in the technical section.

Power station

Lime being the most cost effective alkali, is extensively used in the removal of acidic gases released by power stations. Milk of lime and hydrated lime is sprayed into the flue gas stream (usually Sulphur Dioxide) promoting a reaction to form insoluble calcium sulphate which can then be collected and disposed of. This not only helps clean the air we breathe, but it reduces amounts of acid rain and greenhouses gases, aiding in the ever increasingly important fight against climate change. Power stations and incinerators around the world regardless of what fuel they may burn (i.e. municipal or industrial waste, clinical waste, animal carcasses or natural fuels) have utilised lime as a means of removing these harmful gases many years, arguing that lime is not only cost effective, but also incredibly efficient and sustainable.

Download:Grimsby Operations: flue gas treatment

Contaminated land

Often referred to as Stabilisation/Solidification (S/S), lime can also be used for the remediation of land affected by contamination, as commonly found on brownfield land or derelict sites. S/S is a civil-engineering-based remediation technique in which contaminated soil is mixed with lime and cement to improve its engineering properties and immobilise contaminants. The dual action means that it is suitable for both land of poor engineering properties and land affected by contamination. A large majority of derelict and brownfield land sites are made up of poor land containing contaminants and so S/S provides a practical technique that provides cost-effective remediation. In addition, (S/S) is also a useful technique for treating particular wastes before disposal to landfill.

Wildlife sanctuary from old quarry

Old quarries are restored using inert waste. Restored land often maintains a higher level of biodiversity than the area did prior to quarrying. In fact, the majority of restored sites are now categorised as ‘National Nature Reserves’ of ‘Wildlife Sanctuaries.’  A number of old quarries also transform into shallow wetlands which provide habitats for a wide array of rare and endangered bird species. Over 700 Sites of Special Scientific Interest (SSSI’s) have been designated on former quarries, a large number of which were used to quarry limestone.