SEPARATION OF CHEMICALS

Removal of chemicals from wastewater

Understanding the detailed makeup of wastewater allows one to estimate and conduct the degree of treatment required to make discharge back to the environment safe without deterioration to the original natural water quality.  Uncleaned wastewater poses a serious risk to waterways. The most common organic wastewater components are proteins, carbohydrates, fats, oils, resins, dyes, phenols, petroleum products, detergents, pesticides, etc.  The most common inorganic components are inorganic acids, heavy metals (lead, copper, mercury, zinc, cadmium, chrome) as well as arsenic, chlorine, hydrogen sulphide, sulfate, chloride, nitrate, phosphate, carbonate, ammonium, etc.  When wastewater enters a treatment plant, nitrogen is present in organic compounds and in ammonium salts. The process of nitrogen removal goes through stages.  In the initial stage, organic nitrogen compounds are converted to ammonia and ammonium salts and then under aerobic conditions, ammonia compounds are oxidized to nitrites and nitrates as the result of nitrification. The next stage is denitrification which under anaerobic conditions, nitrates are reduced to molecular nitrogen.

Regarding the removal of ammonia from wastewater, numerous studies have shown that in nature there are at least two different mechanisms of biological oxidation of ammonium compounds under anaerobic conditions.  Bacteria belonging to aerobic nitrifiers such as eutrophil Nirosomonas can reduce nitrites by using ammonium compounds or hydroxylamine as an electron donor.

Esmil Tube Air Diffusers at Municipal WWTP (Harbin, China)

Another group of autotrophic microbes use nitrites as electron acceptors to achieve more efficient oxidation rates of ammonia. This method of oxidation of ammonium compounds is termed anammox (anearobic ammonia oxidation).

Fluoride ions can be removed from the wastewater by means of membrane techniques, absorption, chemical precipitation, coagulation, electrocoagulation or ion exchange.  Fluoride wastewater treatment efficiency depends on process conditions, initial fluoride concentration, pH levels or the presence of accompanying ions.  The types of mercury of most concern in wastewater are soluble mercury (Hg2+) and particulate mercury (Hgp).  The treatment process for mercury removal from wastewater can be as simple as a settling pond.

A more complex wastewater treatment system typically includes several separate operations including desaturation, equalization (to stabilize influent pH), metals precipitation, coagulation, clarification and filtration.

Hydrogen sulfide in the sewage network is formed during wastewater decomposition. This process most commonly occurs in pipelines due to the development of anaerobic bacteria.  Simple methods of hydrogen sulfide removal include pipe-end techniques, biofilters and activated carbon filters and gel sublimation substances. The higher the concentration of hydrogen sulfide, the more common the use is for oxidizing reagents or iron ions.

Esmil Industrial Group offers solutions based on coagulation, filtration under pressure and aeration.

Esmil equipment application in this solution:

• DAF – Unit
• Polymer solution preparation unit
• Chamber-membrane filter press
• Aeration system – tube air diffusers

Our services