Low Cost Technology for Wastewater Treatment in Developing Countries

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 biomassreported 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*.

*Egyptian limits for treated wastewater discharge to surface water ,law 48 of the year 1982 for the protection of the river Nile.

References

[1] S. A. Abbasi, N. Abbasi and R. Soni, Heavy metals in the environment,

Mittal, New Delhi, 1998.

[2]Ajmal,M.;Rifaqt,A.K.and Siddiqui,B.A.Environ.Monit.and Ass.,38, (1995) 25-35.

[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.

[4]Wang.T.C.;Weissman,J.C.;Ramesla,G.;Varadarajan,R. and Benemann,J.R.: Environ. Cont. Toxico.60 (1998) 739-744.

[5] F.E. Okieimen, E.U. Okundia and D.E. Ogbeifun, J. Chem. Tech.

Biotechnol. 51 (1991) 97.

[6] I. Gaballah and G. Kilbertus, J. Geochem. Explor. 62 (1998) 241.

[7] G. Sun and W. Shi, Ind. Eng. Chem. Res. 37 (1998) 1324.

[8] V.K. Gupta, D. Mohan and S. Sharma, Se. Sci. Technol. 33 (1998) 1331.

[9] N. Khalid, P.O. Nilore, S. Ahmad, S.N. Kiani and J. Ahmed, Sep. Sci.

Technol. 33 (1998) 2349.

[10] M. Ajmal, R. A. K. Rao and B.A. Siddiqui, Wat. Res. 30 (1996) 1478.