As we all known, groundwater, specifically well water, contains many dangerous substances, common such as iron, manganese, lime scale ( Scale of CO3, SO4 ), H2S, NH3, toxic microorganisms, substances causing high cancer risk such as Arsenic, Cyanide, organic compounds of pesticides, herbicides, even salinity, Fe – Mn contamination. The treatment of groundwater in general and of well water in particular is considered urgent, but we face many difficulties such as long time and high cost to build this treatment project

Please refer to the article “Understanding the quality and treatment of groundwater and surface water”

1- What is well water treatment?

Groundwater treatment or drilling water treatment is to remove hazardous substances from polluted water with an appropriate method to obtain water quality for domestic use according to current QCVN 01-1: 2018 / BYT standard.

So far, there are some basis processes for well water treatment. To select the best method for long time stable, we can delet out or add to some steps that should be based on water characteristics, capacity and space for construction.

Because well water quality changed seasonally or the depth of the well, quality statistics for a year is overviewed to design the best

In addition to explaining process and the basic steps, we – UCE Co. Ltd also make a difference so that you can clearly see the advantages and disadvantages of each option.

We have finished succesfully many underground water treatment projects with different technologies. For deeper understanding, we offer 2 treatment options, only briefly mentioning the main points. If you want to learn more or prepare a plan for an upcoming project, upgrade or maintain an existing plan, just contact us!

Causes of groundwater polluted

Causes of groundwater polluted

Well water is polluted with Iron

Well water is polluted with Iron

Well water overpopulated with manganese

Well water overpopulated with manganese

Although the well water has just been pumped up with transparent,  quality is still not yet confirmed until checked with specialized devices

Although the well water has just been pumped up with transparent,  quality is still not yet confirmed until checked with specialized devices

Wells are polluted by waste water from traditional craft villages

Wells are polluted by waste water from traditional craft villages

2- Well water treatment with traditional techniques (using chemical)

The following is general process, depending on the quality and quantity of treating water, which can be adjusted or bypassed the treatment stage to be suitable

Process of treatment

. There are 4 main steps in the process of treating well water to domestic water.

Treating groundwater to domestic water with chemical added

Treating groundwater to domestic water with chemical added

Oxidizing

  • Use oxygen from the air to remove CO2, H2S,… and reduce iron, manganese, ammonium, and arsenic.
  • Enhance, accelerate oxidation and kill bacteria with chemical, such as Chlorine.

Sedimentation

  • Removes solid particles, oxidized substances, suspended compounds, and other residues from the water source through the settling stage. Besides, sludge is collected and removed at the bottom of the settle tank by suction pump and drain valve in automatic or manual fashion. This step can remove up to 90% of impurities.
  • To faster and achieve better settling efficiency in well water treatment process, can mix more sedimentation aids such alum of aluminum, iron; PAC, Polymer and adjust pH with NaOH.
  • Sedimentation tanks can be increased efficiency by adding upflow stopping plates with suitable inclination ( 45 – 60 degree )

Multimedia filter ( MMF)

  • Remove again the remaining suspended impurities (approximately 10%) from the water through suitable filter media. Can be filtered by pressured sand filter or naturally gravity filter.
  • Backwash to remove the residue on filtering media by the reverse flow of water from bottom to top of the tower.
  • Using UF filter is also a modern process alternative to sand filter

Active carbon filter.

  • The main function of this step is to caught residuals of organic, odorants and some hazardous substances that have not been removed from the previous steps.
  • Remove the absorbent out of active carbon by backwashing, it also can be regenerated with hot steam, however this is not easy to do without a boiler nearby.

Advantages

  • Chemical can be adjusted to ensure the stable quality if there is worse from source
  • Chemical will make the treatment result faster
  • Easy to operate in generally
  • if there is a large surface area for sedimentation tank, chemical maybe not needed.
  • Can remove many heavy metals and a part of sulphate, hardness, silica from high to medium concentration.
  • Can be converted for surface water treatment (river, stream…).

Dis-Advantages

  • Requires a large area.
  • High operating costs due to chemical need
  • Although easy to operate, the use of chemical must be monitored to avoid too little or much, also its safety

Well water treatment for household

Well water treatment for household

3- Well water treatment with special techniques without chemical

Process

According to this technique, instead of using chemical, oxygen from the air is used for maximum reactions that all happening in only one tank. The feature of this well water treatment method is to use the maximum amount of oxygen to the saturation level to oxidize impurities. The oxidized substances will be deposited on the surface of the sand layers, separated by spray washing from the top and pushed out, while maintaining the stability of the lower sand filter layers. This washing step is called partial washing.

In the lower layer, will continue to occur oxidation by oxygen and microorganisms to convert to MnO2 that both removed from the water, and useful for absorbing heavy metals and some remaining gases. By washing with water from the bottom, it will remove the substances from the surface of the sand layer, which is mainly manganese.

Well water treatment process without chemical added

Well water treatment process without chemical added

Advantages of well water treatment without chemical compared to traditional techniques

  • Without chemical used will save operating cost because only electricity cost
  • Significant space saving for project (about 50%).
  • With high load capacity for iron, manganese and ammonium but still can keep stable in quality after treatment.
  • There is no cost to change materials because only filter sand, at least once every 5 years, while sand is a cheap material.

Dis-Advantages of well water treatment without chemical compared to traditional techniques

  • Maybe need the longer test run if well water with lower manganese but higher ammonium
  • Contractor must have a lot of experience to design, operate and maintain because this is deep technic
  • It is difficult to combine surface water treatment (rivers, streams) if the load is high.
  • Still need disinfection treatment for next step with Chlorine, UV, Ozone…

Well water treatment to domestic water with some components that are difficult to remove

In groundwater, including domestic water, there are many cases of salinization, containing high salt content (TDS, chloride), high hardness (Ca, Mg) or Sulphate, Nitrate groups, etc., it is necessary to remove a part of these components for good quality water, without taste and meets safety standards for health.

The removal of these components by two process above is very limited or impossible. Therefore, it is necessary to combine other processing stages, such as following:

  • Softening with ion exchange resin: Remove the desired hardness, can completely remove the hardness.
  • RO membrane filter: Removes all components (chloride, TDS, hardness, SO4, NO3…). However, it should only be partially filtered because of high investment and operating costs if water is used for domestic use, as well as no more useful minerals remaining
  • Electrolysis and sludge collection with FujiKlean technology: Part of the salt will be removed, these components will be reduced by collecting deposits at the electrode, but only a system with a small capacity should be applied.

Just contact us – UCE Co. Ltd for your long-term solution, saving investment and operating cost.