Low Cost technology for wastewater treatment in Developing Countries
1-Natural Materials for remove of toxic and heavy metals from wastewater
M.N.RASHED
Faculty of Science , Aswan, Egypt .E.mail: mnrashed @ hotmail.com
Introduction
The pollution of water and soil with metallic cations and heavy metals has
increased dramatically in the last 50 years as a consequence of the expansion of
industrial activities. The well-established toxicity of metals in solution at
sufficiently high concentrations affects humans, animals and vegetation [1].
Major sources of metals in the environment are wastewaters from industries like
batteries manufacture, metal extraction, surface finishing and paints.
In developing countries they seeking of the low cost materials or recycling the
solid wastes for the treatment of wastewater from metallic pollutants . One of
such treatment method, adsorption onto solids, is an attractive alternative to
chemical precipitation and ion exchange for metals removal.
Two types of such materials are:
1- rocks and plants as naturally occurring materials : Rocks and ores are zeolites
[1], bentonite , pyrolusite [2], kaolin ,barite and chalcopyrite [3] .
Other study [4] on the heavy metals binding and removal by Phormidium sp
biomass reported the highly maximum adsorption , Pb (13,600 mg/kg) and Cu
(10,100 mg/kg) , while it was nearly the same for Cd (9,600 mg/kg) and Zn (9,400
mg/kg).
2-Sorbents prepared from natural organic wastes used in the removal of
cadmium, chromium, copper, iron, nickel, lead and zinc includes groundnut
husks [5], bark [6 ], sunflower stalks [7], bagasse [8], rice husk [9] and
sawdust [10].
These wastewater treatment adsorbents can be used successfully as a low-cost
materials in developing countries and can be found in a large quantities .
Case Study
Kaolin as naturally ore for wastewater treatment from heavy metals
Wastewater treatment using kaolin. After concluded the suitable conditions for
the adsorption of heavy metals Fe,Cd,Cr,Co,Cu,Sr, Mn and Pb on kaolin using
standard solution, drain wastewater from fertilizer factory was applied for the
removal of heavy metals using kaolin .Treatment with kaolin ore size <63 µm
exhibited the high efficiency for the complete removal of heavy metals. The
adsorption per cent were 100% for Cd , Cu, Cr,Mn and Pb. Kaolin reduce the
concentration of Fe ,Sr and Zn ( adsorption per cent 92%,94 % and 88 %
respectively ) . Kaolin treatment method was very effective for the removal of
heavy metals Fe,Cd,Cr,Co,Cu,Sr, Mn and Pb than aeration and alum methods
which used previously .
The results of the wastewater treatment processes (Table 1 ) were in the limits
cited by Egyptian Authority for discharge into surface water or reuse for irrigation .
Table 1:Heavy metals levels(ppb) in Alum treatment samples and Egyptian
standard*.
Sample
Original sample
Alum treatment
Kaolin treatment
Egyptian Standard
Fe
430
30
1
Cd
30
0.0
0.0
Cu
22
0.0
0.0
Cr
Sr
32
150
0.0
10
0.0
0.80
1000 ppb
Mn
40
0.0
0.0
Pb
32
0.0
0.0
Zn
80
10
0.9
*Egyptian limits for treated wastewater discharge to surface water ,law 48 of the
year 1982 for the protection of the river Nile.
References
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Mittal, New Delhi, 1998.
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[3] M.N.Rashed and M.E.Soltan .Removal of heavy metals from urban
wastewater using aeration,alum and kaolin ore .In: In: Proceedings of
International Symposium “Frontiers in Urban Water Management :Deadlock or
Hope?” 18-20 June 2001, Marseille, France. HIP-V \ Technical documents in
hydrology\No.45, UNESCO, Paris, 2001.
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