Water and Wastewater treatment chemicals
Coagulants
Coagulation is the first and the most important step in physicochemical water and wastewater treatment. With the coagulants we destabilize the colloidal suspension of a system, and through the Brown kinetics, the neutralized particles are merged to form the first micro-flocs. At the next step, these micro-flocs will be bridged by a flocculant to form bigger flocs. The coagulation process demands high shear power which is supplied either by an agitator or by an existing turbulent flow.
Α) Inorganic coagulants
Ferric salts
Ferric chloride
Ferric chloride sulfate
Polyaluminium chloride 18% (PAC 18)
PAC 18 - Low basicity
PAC 18 - High basicity
Aluminium sulfate
Powder
Solution 45% w/w
Sodium aluminate
Available in three concentrations, 8%, 10% and 12% w/w in aluminium cations.
Β) Organic coagulants
Polyamines
pDADMAC
C) Tailor made coagulants
Blends of organic and inorganic coagulants
Decolourants
Dicyan-Diamide Decolourants.
Decolourants are mainly used in the textile industry’s wastewater treatment, where dyes are used in the textile production process. An indicative example is the “indigo” deep blue dye for the jeans. The decolourant reacts with the chromophore groups by breaking the nitrogen bonds.
Polyelectrolytes
The polyelectrolytes are polyacrylamides who are categorized as cationic, anionic and non-ionic, according to their charge.
The main use of cationic polyelectrolytes is the flocculation of the activated sludge, at wastewater treatment plants.
A cationic polyelectrolyte solution is added to the surplus activated sludge (1-3% in dry solids), where the formation of large flocs is occurred. The mixture of flocs and water is then driven either to a belt filter press or to a centrifuge (decanter) where a sludge cake is produced (15 – 30% in dry solids). The clean separated water (filtrate or centrate) returns to the entrance of WWTP. In this way, the surplus activated sludge is systematically removed from the plant, allowing the smooth operation of the final clarifiers.
Traditionally, the main use of anionic and non-ionic polyacrylamides, is the flocculation of the particles of mineral sludges. This is for example the wash waters of a quarry, where the flocculated by the anionic polyacrylamide solids, are settling and then removed as a sludge cake through a frame filter press.
Nowadays, the major volume of anionic polyacrylamides is used in oil extraction. When the oil wells are almost dry, anionic polymer solution is injected into the oil reservoir. It works by increasing the viscosity of the injected water, thus improving its mobility and oil recovery (Enhanced Oil Recovery, “EOR”).
Another use of the polyacrylamides, anionics and cationics, is at the second step of physicochemical wastewater treatment. Their role is very important as they are bridging the small micro-flocs who were formed at the first step of the treatment (coagulation), forming bigger flocs, allowing in this way an effective floatation or settling or filtration of these flocs. So, the wastewater, now free from most of the suspended solids, can enter the next stage of treatment (biological treatment) or to be directly disposed of into a river or sea.
Our company has a full product range of polyelectrolytes:
Cationic polyacrylamides
(powders and emulsions)
Anionic polyacrylamides
(powders and emulsions)
Non-ionic polyacrylamides
(powders and emulsions)
Defoamers
Defoamers are either liquids or powders, and they are used to destroy the already formed foam (knock down) and to prevent the re-formation of new foam (de-aeration of the media). They have a lot of applications in the wastewater treatment, in the food industry, in sugar production, in mining activities, etc.
Two terms are used to categorize these products:
Defoamers and Antifoam agents.
The term “defoamer” characterizes the products who have as a main action the knock down of the foam. The term “antifoam agent” characterizes the products who prevent the foam formation.
In our company there is a wide range of defoamers and antifoam agents.
Deodorants
Hydrogen sulfide scavengers
They are used in cases where hydrogen sulfide is released from the liquid phase to the air phase. These products react with the hydrogen sulfide in the liquid phase, preventing this way the release into the air phase.
Masking agents
ΕThese are neutralization agents who cover the unpleasant odors, without reacting with odorous compounds. They are hyper-concentrated mixtures who mainly contain terpenes.
In our company you can find masking agents with different odors.
Biotechnology products
Pre-selected bacteria blends (powder)
Pre-selected bacteria blends are mainly used at the start-up of a wastewater treatment plant (WWTP) until an effective and sufficient biomass has been generated. In some industrial wastewater, it is necessary to add bacteria systematically to the system, if the environment in the aeration basins does not allow to maintain a healthy biomass. This could happen if the pH of the wastewater varies a lot, if the ratio C:N:P varies a lot, if the influent is sometimes toxic for the biomass (eg if it contains chlorinated detergents), etc.
Enzymes (lipases)
Lipases are used in WWTP where fats oil and grease (FOGs) are present in high numbers in the aeration basins. This could happen if the oil skimmers are not working properly or if it is insufficient due to subsizing.
A characteristic example is the hotel kitchens, where big amounts of FOGs escape from the skimmers and flow unhindered to the aeration basin.
Filter media
In our company you can find the following filter media:
Activated carbon
Granular (GAC): it is used for liquid filtration
Pellet (extruded): It is used for gas filtration. It can be a simple activated carbon or an impregnated activated carbon. For the impregnation it is used either sodium hydroxide, potassium hydroxide or potassium iodide. The impregnated grades are ideal for the adsorption of hydrogen sulfide.
Powder (PAC): it is used in both liquid and gas filtration. The liquid or the gas is mixed with the powder activated carbon and then it is filtered (we must take care to secure a sufficient contact time between the stream and the carbon).
Activated alumina
It is used in gas filtration when the main target is hydrogen sulfide adsorption.
Quartz sand
It is used in liquid filtration to retain the suspended solids.
