Phosphates & Surfactant in WWTP

Published on by in Business

Dears,

I am trying to find an ideal solution for my plant. The WWTP ( domestic ) is having phosphates of 20 ppm & need to guarantee outlet of < 1 mg/l. Moreover , surfactant existed in the plant & is required to be removed. What would be ideal for phosphates removal , 

a. Having anaerobic tank a head of biology ( with about 0.5-1 hour retention time ). What would be the expected removal efficiency to achieve?

b. Primary settling with coagulation of Iron Salt or Alum. Again , any idea of design basis for settling tank as well as the dosage? What would be the expected removal efficiency to achieve?

Regarding surfactant , would the usage of the primary settling along with coagulant enhance the removal? What would be the expected removal efficiency to achieve?

Any suggestions/recommendations?

Thanks

Dania 

Taxonomy

1 Answer

  1. Chemical precipitation is used to remove the inorganic forms of phosphate by the addition of a coagulant and a mixing of wastewater and coagulant. The multivalent metal ions most commonly used are calcium, aluminium and iron. Calcium: it is usually added in the form of lime Ca(OH)2
    it is usually added in the form of lime Ca(OH)2. It reacts with the natural alkalinity in the wastewater to produce calcium carbonate, which is primarily responsible for enhancing SS removal.
    Ca(HCO3)2 + Ca(OH)2 à 2CaCO3 ↓+ 2H2O
    As the pH value of the wastewater increases beyond about 10, excess calcium ions will then react with the phosphate, to precipitate in hydroxylapatite:
    10 Ca2+ + 6 PO43- + 2 OH- ↔ Ca10(PO4)*6(OH)2 ↓
    Aluminium and Iron:
    Alum or hydrated aluminium sulphate is widely used precipitating phosphates and aluminium phosphates (AlPO4). The basic reaction is:
    Al3+ + HnPO43-n ↔ AlPO4 + nH+ 
    Ferric chloride or sulphate and ferrous sulphate also know as copperas, are all widely used for phosphorous removal, although the actual reactions are not fully understood. The basic reaction is:
    Fe3+ + HnPO43-n ↔ FePO4 + nH+ 
    Surfactants are one of these emerging contaminants. They are of interest because of their increasingly ubiquitous domestic and industrial use and the difficulty their presence causes traditional treatment. In response to this developing area, such as Carbon Nanotube (CNT) used.  carbon nanotube (CNT) is a tube made of carbon with diameters typically measured in nanometres.Single-wall carbon nanotubes (SWCNTs) Single-wall carbon nanotubes are one of the allotropes of carbon , intermediate between fullerene cages and flat graphene , with diameters in the range of a nanometre. Although not made this way, single-wall carbon nanotubes can be idealized as cutouts from a two-dimensional hexagonal lattice  of carbon atoms rolled up along one of the Bravais lattice  vectors of the hexagonal lattice to form a hollow cylinder. In this construction, periodic boundary conditions are imposed over the length of this roll-up vector to yield a helical lattice of seamlessly bonded carbon atoms on the cylinder surface. The ability of multiwalled carbon nanotubes (MWCNTs) to remove a non-ionic surfactant, Triton X-100 (TX100), an anionic surfactant, sodium dodecylbenzenesulonate (SDBS), and a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB) from the aqueous phase was investigated. Untreated, OH-, and COOH-functionalized MWCNTs with different outer diameters and chemical composition were examined and compared. As both the concentrations of surfactants and MWCNTs initially added may affect removal efficiency of surfactants, a relationship between the initial concentration ratio of surfactants and MWCNTs (Rc) and the removal efficiency (E) was established.