Sulfate removal from water

Sulfate is one of the world’s most widely used commodities. Although not very toxic, excessive discharge of sulfate can lead to ecological problems. Used water in the chemical industry often contains organic material in addition to sulfate. SULFATEQ^™ provides simultaneous COD and sulfate removal, whilst producing elemental sulfur that can be reused for other purposes.

Concentrations of metals like copper, zinc or nickel of just a few dozens mg/L in acid mine or rock drainage can be economically recovered using SULFATEQ^™ or THIOTEQ^™ Metal.

The number of bioleaching operations to release metals from ore and concentrate is growing rapidly. There are a number of reasons why SULFATEQ^™ is ideal for dealing with bleeds from the acid recycle in such operations:

• It converts sulfate into sulfide that can be used to precipitate metals as marketable pure metal sulfides.
• It converts excess sulfate into elemental sulfur that can be reused in heap or tank leaching as in-situ acidification agent.
• It precipitates calcium and magnesium as carbonates that can be used elsewhere in the process.
• It generates reusable water.

Many pyrometallurgical operations produce gaseous sulfur dioxide that is converted into sulphuric acid. Gas cleaning produces a weak acid as waste, which is often heavily polluted with a variety of metals with a positive (zinc, cadmium, lead etc.) and a negative value (arsenic). Paques tailor-made technologies allow for maximum recovery of valuable resources and minimal production of waste for disposal.

For more than 15 years, SULFATEQ has been applied in full-scale installations. Its bioprocesses for sulfate removal in water are preferred over chemical processes in sulfate removal. Not only because they are more sustainable, but also because of specific advantages. SULFATEQ is a safe, effective and odor-free process for sulfate removal without lime. It simultaneously recovers valuable metals, such as copper, nickel and zinc, and removes calcium, magnesium, manganese, selenium, thallium, etc. It treats acidic, alkaline and pH-neutral streams in ambient conditions. The effluent is improved and reduced. And often, the effluent is free of solid waste and wastewater is reused in the facility.