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Wastewater treatment

Wastewater treatment

MagTreat® is a natural reagent for wastewater treatment. It can be effectively used in primary and secondary treatment processes. Acting like a soft alkali, MagTreat is safer and more effective than any of existing industrial alkalis. It can be applied on each stage of sewages purification, improving the perfomance of a whole process.

Odor is a wide spread problem in waste water treatment facilities. It can affect an environment, operational personel and also can severely damage the eqipment. Thereby, the question of Odor Control araises sharply these days. MagTreat can reduce odor formation not only on initial stages of water treatment process but at the same time on the final stage during biosolids processing. MagTreat reduces the costs of utilizing solid wastes via improvement of sludge dewatering.


Acid sewages neutralization


Due to lower molecular weight magnesium hydroxide provides more hydroxyl ions than hydrated lime and more than monovalent caustic soda per kg. One mt of NaOH is equivalented to 0.73 mt Mg(OH)2 and one mt of Ca(OH)2 is equivalented to 0.79 mt Mg(OH)2.It is vividly illustrated by dissociation reactions*:

2NaOH ó 2Na+ + 2OH-

2(40)g/moló 2(23)g/mol + 2(17)g/mol

Ca(OH)2 ó CaOH+ + OH- ó Ca2+ + 2OH-

(74)g/moló(57)g/mol + (17)g/mol ó (40)g/mol + 2(17)g/mol

Mg(OH)2 ó MgOH+ + OH- ó Mg2+ + 2OH-

(58)g/moló (41)g/mol + (17)g/mol ó (23)g/mol + 2(17)g/mol

*On dry solids basis


Unlike many commonly used chemicals as hydrated lime or caustic soda, MagTreat® gradually neutralizes acids reaching the maximum pH level of 9-9,5 forming safe buffer solutions. Also, there is no exceeding calorification during neutralization process. MagTreat is effective in neutralization of both inorganic and organic acids:


  • Sulfuric acid
  • Hydrochloric acid
  • Phosphoric acid
  • Nitric acid
  • Acetic acid

MagTreat allows to prevent scaling of the equipment in reaction with sulphuric acid and phosphoric acid. It forms products that can be easily removed out of the system - magnesium sulphate and struvite (MgNH4PO6H2O).Treated water is enriched with magnesium ions and have pH level supportable for the next stage of wastewater treatment.

Efficacy of the products AquaMag


Heavy metals reduction

MagTreat helps to reduce concentration of ions to the values of the MPC, while treatment of wastewaters with high content of heavy metals.

When added to a system MagTreat acts like an alkali and a sorbent at the same time. It precipitates heavy metal ions as hydroxides which form colloid suspensions. It effectively removes such dangerous elements as copper, lead, cadmium, zinc, chromium, etc.

Mg(OH)2↔ Mg2++ 2OH-Me2++ 2OH-= Me(OH)2↓where Me2+— ions Fe2+, Cu2+, Ni2+, Zn2+, etc.

At the same time MagTreat absorbs heavy metals, thanks to its high specific surface area about 11 m2/g. The absorption capacity of natural magnesium hydroxide is comparable to the absorption capacity of synthetic ion-exchange materials.


Biological wastewater treatment

MagTreat can be used for secondary water treatment – nitrification/denitrification process. It helps to maintain the optimal pH level for bacteria reproduction. Biological wastewater treatment could be performed either as a joint process of aerobic-anaerobic treatment by activated sludge, or as a two separate processes: nitrification in aeration basin and denitrification inside a methane tank.


Nitrification improvement mechanism:

Nitrification is biological oxidation of ammonia via nitrite to nitrate:NH3NO2NO3

The process occurs in two steps. Both include activity of different bacteria that are extremely sensitive to pH level. Below you can see a graph illustrating dependence of maximum nitrification rate on pH of the system.


Nitrification rate.jpg

Percent of maximum rate of nitrification at constant temperature (20 C°) versus pH

Source: EPA-625/4-73-004a, Revised Nitrification and Denitrification Facilities Wastewater Treatment, U.S. Environmental Protection Agency Technology Transfer Seminar.

MagTreatbuffers at a pH of approx. 9, which is in most cases the optimal level for bacteria reproduction.Thanks to the unique properties it is impossible to overshoot the pH, whereas NaOH can easily reach a pH of 13 and Ca(OH)2 a pH 12. At these pH levels the biomass will sustain severe damage.

Further you can see an illustrated cost-reduction efficiency of MagTreat in comparison with other alkalis:


1.JPG

1 IBC of MagTreat 3 IBCof Ca(OH)2

60% suspension 30% suspension

2.JPG

1 IBC of MagTreat 1.6 IBC of Na(OH)

60% suspension 50% solution


Odor control

A common problem of sewage systems is“rotten eggs” smell, caused by presence of gaseous H2S.In acidic media at a low pH sulfur is being converted to sulfate ions SO42-and then into hydrogen sulfide. TheThiobacillusbacteriaconsumesoxygenfrom airandH2S gas and forms highly corrosive sulfuric acidH2SO4

Thereby the presence of odor in the sewage system indicates that steel and concret consructions could be demaged.Passing into the WWT system at the pretreatment stage MagTreatraises pH level up to 9. At such levels almost no gaseous H2S is forming. So MagTreat not onlyreduces odors, but alsohelps to preventcorrosion of the equipment vianeutralization of sulfuric acid.

Liquid/gas phase diagramm in HS-/H2S system. At low pH lever of 5 the concentration of gaseousH2S is 50 times higherthan at higher pH of aprox. 9, when there almost no gaseous H2S is forming.


Improvement of flocculation and biosolids processing

Flocculation process can be affected by a content of monovalent cations, which are incerted into WWT system with household detergents or sodium based water softeners, or from neutralizing agent based on caustic soda.Thanks to the bivalent Mg2+cations MagTreatenhances the joining of long polymer molecules (for example, FOG + bacteria) which make them easier to flocculate and separate from water. When added into the sewages. MagTreatimproves not only primary treatment process but also dewatering during biosolids processing. It is also useful for limiting of the odors (mainly H2S) emissions during transportation and storage of biosolids.

Hydrogen sulfide is the main component of odors emissions and causes a rotten eggs smell. MagTreatraises pH level in the pressed solid mass to approx. 9. At such level almost no gaseous H2S is formed.Magnesium hydroxide particles dissolve slowly they stay active during a long period oftime,working like a buffer whilst maintaining an adequate pH level in the system.

MagTreat

Solutions for this field

The most demanded products of RMCC in this field are:

MagTreat®


MagTreat - P20R
(PDF, 311.70 )
MagTreat-S10R
(PDF, 312.70 )
MagTreat-P10R
(PDF, 312.66 )
MagTreat-S
(PDF, 312.32 )
MagTreat-P
(PDF, 311.97 )

Contact us, our experts will provide you with advice on the use of the product

MagTreat®
+7 495 789 65 30 sales@magminerals.ru