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Water and Wastewater

Treatment of drinking water

It is well-known that for hygiene reasons as well as reasons related to the treatment technology of drinking water, water coming from springs or water-wells is primarily used. However, the ever-increasing consumption, especially in densely populated areas, can no longer be met. Thus, one is obliged to reside to the use of surface water  so as to fulfill long or short term demands for fresh water. The treatment of water before consumption is essential so that the water with which one ends up meets the health and safety regulations for drinking water. Essential processes are filtration, flocculation with products certified for the treatment of drinking water, and disinfection by appropriate means. 

The purpose of FERI-TRI SA is to supply the companies responsible for drinking water with appropriate chemical products to curb unpleasant side-effects in humans.

Treatment of swimming - swimming-pool water

The water of any swimming pool, small or large, must be cleaned on a daily basis so as to avoid contraction of various diseases that may be transmitted through pool water. Necessary treatments are filtration, flocculation with products certified for the treatment of drinkable water and disinfection by appropriate means. The purpose of FERI-TRI SA is to supply swimming pools with necessary chemical products so as to avoid unwanted consequences for human health.

Treatment of municipal wastewater

Municipal water is the liquid waste generated during cleaning processes (cooking, laundry, toilets, etc.) in a residential area (offices, schools, houses, etc.). The treatment of urban wastewater is now necessary so that the water which ends up at  a final destination (lakes, rivers, sea, land) is in the best possible condition, in order not to degrade the water resources of our planet. The water that has been properly processed can be reused in ways such as:

  •  Farmland irrigation
  • Irrigation of parks/ football fields/golf courses, open spaces in shops/industries, etc.
  • Industrial activities, mainly for refrigeration
  • Enrichment of groundwater, either through spreading basins or by direct infusion in the undergoing aquifer.
  • Environmental/recreational use, including a number of uses other-than-drinking but associated with activities related to water, eg recreational water areas, enrichment of wetlands or enhancement of streams
  • Fire extinguishing, air conditioning, toilet cleaning or construction.
  • Drinking water is obtained after mixing the recovered water with raw drinking water.

Treatment of industrial wastewater

Industrial wastewater is industrial effluent generated during various industrial processes. These can take place in paint shops, slaughterhouses, canneries, dairies, etc.  Processing is necessary so that the water which ends up in municipal water/ sewage companies or final recipients (lakes, rivers, sea, land) is in the best possible condition and, in accordance with environmental requirements for the disposal of industrial effluents.

The processing required in each industry depends on the quality standards of each, the final recipient or the intended use of greywater, and the available financial and technical resources.

ACTIONS

FLOCCULATION

Flocculation is one of the most important processes to which the water must be subjected at an early stage, in order to remove the suspended and colloidal particles, after the sedimentation and precipitation which follow.

In water treatment technology, coagulation is becoming more important and a large number of technologies were developed for this purpose.

 When selecting the medium for flocculation, one must take into account mainly the following parameters, inorder of priority:

1.  Its price must be affordable.

2.  It must have  very good flocculent properties.

3.  It must be soluble in water.

4.  The dosimetry must be simple and functional.

5.  It must not contain contaminants which pose various risks to the environment.

Where sewage treatment plants are overloaded (since the load of dirt may often increase abruptly) the flocculent products, which promote the formation, concretion and sedimentation of persistent organic substances, increase the efficiency of the plant and the degree of purification.

The salts or the iron and aluminium solutions, have the property of precipitation of phosphate (up to 95%), nitrogen and arsenic at a very large percentage of the water mass. They also bind and remove sulphide and sulphurs. Also, ferrous salts have the property of reducing hexavalent chromium to innocuous trivalent chromium. Flocculants generally do not allow the formation of floating sludge and significantly increase the texture of compact sludge that ends up in industrial greywater treatment systems and municipal wastewater, in order to achieve a good degree of dehydration. The flocculation method is also applied when processing brackish water or sea water for the production of drinking water by reverse osmosis. Flocculent is the chemical reagent added to the destabilization of colloidal particles in liquid wastes and flocculent formation. The infusion of flocculants can be done in various parts of the sewage treatment plant such as:

- in the pre-cleaning stage,

- in the biological cleaning stage,

- in the final cleaning stage.

(When flocculation of the raw sewage is in the pre-cleaning stage, both the biological cleaning stage that follows and the organic pre-mixing stage are reduced by 40-60%).

DISINFECTION - NEUTRALISATION - pH ADJUSTMENT

Disinfection is the partial killing of micro-organisms that cause disease. Not all micro-organisms are killed during processing. This fact differentiates disinfection from sterilization during which all micro-organisms are extinguished.

Neutralization is the process to which very acidic or alkaline waste must be subjected so as to avoid problems occuring to recipients because of the high or low pH. Generally, all treated wastewater with too low or too high pH is required to be neutralized before being disposed in natural recipients (river, lake, sea).

PH adjustment is required for a variety of processes in wastewater treatment. Liquid waste which is acidic can be neutralized by the addition of various alkaline chemicals and, alkaline waste by adding acid. No pH adjustment may cause wear (erosion) in waste drains, machinery, etc. Since, generally, many processes take place at a sewage treatment or wastewater plant, specific pH values are required for optimal performance and their control is considered essential.

Oxidation is the loss of electrons and is mainly used:

  • to augment the treatment of non-biodegradable organic matter
  • to eliminate the inhibitory influence of certain organic and inorganic substances on microbial growth
  • to reduce or eliminate the toxicity of certain organic and inorganic substances and microbial growth in aquatic vegetation
  • for the decomposition of organic molecules that are present in industrial effluents and constitute BOD ( e.g. oxidation with ozone, the chloride of hydrogen peroxide)

 

Reduction is the uptake of an electron and mainly used:

  • In metal industries (ferrous sulphate (FeSO4), for the reduction of hexavalent to trivalent chromium
  • In cement industries (ferrous sulphate (FeSO4), for the reduction of hexavalent to trivalent chromium

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PRODUCTS

Title Brand name Form Chemical Type Active substance Applications
ACTIVATED CARBON PELLET, GRANULES, POWDER
ALUMINIUM SULPHATE ALUMINIUM SULPHATE SOLUTION Al(OH)aClb 9-18%
AMMONIUM HYDROXIDE AMMONIA SOLUTION NH4OH 19% ,25%
AMMONIUM NITRATE AMMONIUM NITRATE PRILLS NH4NO3 34,4 %
ANIONIC POLYELECTROLYTES
ANTISCALE AGENT ANTISCALE AGENT SOLUTION
ANTRACITE PELLET, GRANULES
BACTERIA AND BIOTECHNOLOGY PRODUCTS BACTERIA AND BIOTECHNOLOGY PRODUCTS
CALCIUM CARBONATE CALCIUM CARBONATE CRYSTAL, POWDER CaCO3 98,6 %
CALCIUM CHLORIDE CALCIUM CHLORIDE GRANULES, SOLUTION CaCl2 77%, 35%
CALCIUM DIHYDROXIDE HYDRATED LIME HYDRATED LIME Ca(OH)2 > 90%
CALCIUM NITRATE NITRASVESTSOL 50 CRYSTALS, GRANULAR, SOLUTION Ca(NO3)2 99%, 49 %
CATIONIC POLYELECTROLYTES
CHLORINE CHLORINE GAS - LIQUID, TABLETS Cl2 > 99.9 %
COPPER SULPHATE GRANULES CuSO4-5H2O > 25%
DEFOAMING AGENT DEFOAMING AGENT SOLUTION NON SILICONE, SILICONE
DEFOAMING AGENT
FERRIC CHLORIDE FERRISOL 90, 140 SOLUTION FeCl3 9%, 14%
FERRIC CHLORIDE SULPHATE FERRISOL 123 SOLUTION FeClSO4 12,3%
FERRIC SULFATE FERRIXSOL 100, FERRIX 3 SOLUTION Fe2(SO4)3 10%, ~ 19,5%
FERROUS CHLORIDE FERROSOL 90 SOLUTION FeCl2 9%
FERROUS SULPHATE HEPTAHYDRATE POWDER FeSO4-7H2O 18% w/w Fe2+
FERROUS SULPHATE MONOHYDRATE POWDER, GRANULES FeSO4-H2O 31%
HYDROCHLORIC ACID HYDROCHLORIC ACID SOLUTION HCl 1-33% w/w and 36-37w/w (pure grade)
HYDROGEN PEROXIDE HYDROGEN PEROXIDE SOLUTION H2O2 35%, 50%
NON - IONIC POLYELECTROLYTES
POLYALUMIUM HYDROXYDE CHLORIDE PAC NORMAL / HIGH BASICITY. SOLUTION Al(OH)aClb 9-18%
SILICA SAND GRANULES
SODIUM ALUMINATE SODAL SOLUTION Na2O Al2O3.nH2O 10%
SODIUM CARBONATE SODA ASH (DENSE & LIGHT) POWDER Na2CO3 ≥ 92 %
SODIUM CHLORATE SODIUM CHLORATE POWDER NaClO3 98%
SODIUM CHLORIDE SALT CRYSTALS NaCl > 99%
SODIUM CHLORITE SODIUM CHLORITE SOLUTION NaClO2 7,5%, 25%, 31%, 35%
SODIUM HEXAMETAPHOSPHATE SHMP POWDER (ΝaΡΟ4)6 68%
SODIUM HYDROGEN CARBONATE SODIUM BICARBONATE POWDER NaHCO3 99%
SODIUM HYDROGEN SULPHATE SODIUM HYDROGEN SULPHATE GRANULES, SOLUTION NaHSO4 94,5 – 98,5 %
SODIUM HYDROXIDE CAUSTIC SODA SOLUTION, FLAKES, PEARLS NaOH 17-50%, 99%
SODIUM HYPOCHLORITE SODIUM HYPOCHLORITE SOLUTION NaClO ≥12 %
SODIUM METABISULFITE SODIUM METABISULFITE POWDER, SOLUTION Na2S2O5 30%, 40%, 98%
SPECIAL MIXTURE OF COAGULANTS POLYPAC SOLUTION
SULPHURIC ACID SULFURIC ACID SOLUTION H2SO4 97-98 %, 70%,50%,30%