Natural plant coagulants for wastewater treatment

Natural plant based coagulants derived from Acacia for wastewater treatment, series ECOTAN

Servyeco has developed a wide range of natural plant coagulants, ECOTAN series derived from the Acacia. All belong to the family of the tannins. Tannins are polyphenol compounds derived from natural materials such as organic extract of the bark and wood of trees such as Acacia, Castanea or Schinopsis. Depending on their structure are classified into two main categories: hydrolysable tannins and condensed tannins. Have in their chemical structure polihidroxifenil multiple groups that possess a high affinity for proteins, metal ions and other macromolecules such as polysaccharides. The tannins are being extensively investigated to develop a wide range of industrial applications such as use in wood adhesives, ink manufacturing, textile dyeing, water treatment, corrosion inhibitors on steel, antioxidants, drugs or cosmetics, among others.

Tannin molecule
fig. 1 Overview of the tannin molecule

Polymeric coagulants can be either cationic, anionic or nonionic. The first two have been generally referred to as polyelectrolytes. Many studies coagulants appoint natural polyelectrolytes, although they have not been chemically characterized to determine their ionic activity. Therefore, this term should be used carefully and only after determining ion activity present in the coagulant. Coagulants are mostly natural polysaccharides or proteins. In many cases, even polymers that are supposed nonionic load can interact.
It is very important to understand the fundamental mechanism of clotting associated with natural coagulants to have a full understanding of its use. The aggregation of particles in a solution can occur via four classical clotting mechanisms:
- Compression of the double layer: The presence of salt can cause compression of the diffuse double layer surrounding the colloidal particles, which destabilizes the same.
double layer
fig. 2 Schematic view of the double layer

- Sweep flocculation or cross: Occurs when a coagulating suspended particles encapsulated in a soft colloidal floc.
- Neutralization of charges and adsorption by bridges between particles: Refers to the absorption of two particles with opposite ionic charges. This process takes place when there is a bridge between particles, that is, when a coagulant provides a polymer chain which adsorbs particles.

Finally, note that some of these coagulants also have antimicrobial properties, so that reduce or eliminate the content of pathogens capable of causing disease in living organisms.

Characteristics of natural plant based coagulants derived from Acacia, ECOTAN SERIES

Is a natural cationic coagulant that is extracted from the bark of Acacia Negra (Acacia mearnsii) having a strong coagulating action acting in colloidal systems in waste water and neutralizing the agglutinating loads (clotting) particles in suspension. As mentioned earlier, are based on natural polyphenolic polymer, with a strong chelating character, which gives extremely reactive in nature.

Due to its natural character as it has no metals in their structure, do not consume alkalinity of the medium as it does not undergo hydrolysis in solution and its effectiveness as a coagulant is always optimal.

Advantages of using plant-based coagulant derived from Acacia

Working conditions

  • Consumes no alkalinity of the medium to not undergo hydrolysis in solution, so that its effectiveness as a coagulant is always optimal.
  • Does not alter the pH of the system and has an effective range of 4.5 to 9.0.
  • Reduces or eliminates the use of alkalizing agents such as sodium or calcium hydroxide.
  • Protects against corrosion of metal parts, not increasing the conductivity.
  • Provides a rapid flocculation and decantation. May act as a coagulant or flocculant eliminates or greatly reduces the consumption of other flocculants.
Implementation and reuse

  • Improves the cost / benefit over other inorganic coagulants and / or synthetic.
  • Present in the liquid state is ready for use, requiring no previous dilutions or mixtures.
  • It is an organic-based polymer derived from plant extracts, totally environmentally friendly. Not corrosive or toxic, favoring biological processes.
  • To provide non-toxic elements such as aluminum, promotes the dehydration and subsequent re-use of sludge.
Other advantages

  • It acts as a deodorant agent, by abducting sulfide derivatives, precursors of hydrogen sulfide.
  • It acts as a deodorant agent, forming insoluble complexes with organic species such as proteins or carbohydrates.
  • Acts as a chelating agent, complexing different metals such as iron, manganese or aluminum.
  • Interacts with cell wall polysaccharides of bacteria. Thus, reduced consumption of biocides or other tertiary treatments.

Drawbacks of the use of vegetable-based coagulant derived from Acacia

  • The only drawback is that it works in all types of waste water, so you have to do a trial of Jar-test to determine the optimal dosage of each type of water.

Examples of waste water purification plant based coagulants derived from Acacia

Wastewater from fruit, textiles, slaughterhouses
Wastewater from dairy companies, spices, ETAP
Wastewater from companies frozen, paper and cardboard, sewage treatment plant

Acacia mearnsii

Acacia mearnsii, black wattle is commonly called a small, expandable tree measuring 7 to 10 meters high, shaped or conical canopy with branches that reach almost to the ground, they are angular and pubescent, bark smooth, brown the youngest greenish, clouded and rough on the main trunks and often exude a gum.
fig.3 Acacia mearnsii with flowers

Other coagulants natural basis for wastewater treatment

Natural coagulants are water-soluble substances, materials from vegetable or animal origin. These act similarly to the synthetic coagulants agglomerating (clotting) colloidal particles in suspension containing the raw water, facilitating its deposition by a weight gain and a destabilization of the surface charge which keeps the particles in suspension. With this we obtain an initial turbidity reduction. Some of these coagulants also possess antimicrobial properties, so that reduce or eliminate the content of microorganisms capable of causing disease. Its natural origin ensures the safety for humans and the biodegradability of sludge produced can also be used in agriculture.
The use of natural coagulants represents an essential step in environmentally friendly technologies. These products can be extracted directly from certain plants or animals or as modified derivatives of natural materials.

Natural animal-based coagulants for wastewater treatment

Within the natural coagulants of animal origin, the most studied is chitosan. This coagulant is a derivative of chitin which is located in the shell of shellfish, the exoskeleton of arthropods and the cell wall of yeast, fungi and yeasts. It's a good coagulant capable of removing up to 99% of raw water turbidity when combined with sand bed filtration. It is also capable of reducing the content of heavy metals, phosphorus and fats from water.

Natural plant-based coagulants for wastewater treatment

Of all the natural coagulant, the coagulant primary plant best known and studied at present is the seed of Moringa Oleifera. It was originally an ornamental tree in Sudan, planted during the British occupation. Moringaceae is the name of the plant family that includes more than 14 known species, endemic African countries, Madagascar, Arabia and India. Half of them are relatively common today and are rarely cultivated, but only the Moringa Oleifera is cultivated throughout the tropical area. The most common use of Moringa Oleifera seed is the treatment of water, due to its clotting properties, antibiotic and antifungal.

Servyeco Iberia, S.L.Servyeco Iberia, S.L.