Re-use of water treatment sludge (Alum sludge) in enhancement of domestic wastewater treatment processes

Citation:
Re-use of water treatment sludge (Alum sludge) in enhancement of domestic wastewater treatment processes, Elawwad, Abdelsalam, Rashed Ehab, and Sadawy Mohamed , Journal of Al Azhar University Engineering Sector, Volume 4, Issue 11, p.261-272, (2009)

Abstract:

Huge amounts of alum sludge are generated by water treatment plants every day. The common disposal system of alum sludge in Egypt is to discharge it into the nearest waterways. The impact of aluminum toxicity released from sludge on aquatic life has become a significant environmental issue. Re-use of alum sludge in wastewater treatment may provide a solution for issues related to sludge disposal. It may also help to increase the performance of existing WWTPs, because that alum sludge contains a large portion of insoluble aluminum hydroxides that can be utilized as a coagulant in the wastewater settling processes. Therefore, this paper attempted to study the effect of alum sludge addition on primary and secondary wastewater settling processes. Also, effect of alum sludge addition on the characteristics of the settled primary and secondary wastewater sludge was investigated. Alum sludge and wastewater samples were applied to a series of Jar test experiments. Re-use of alum sludge achieved highly removal efficiency values for the primary and secondary settling processes. The volume of primary settled sludge increased and moisture content slightly increased. However, alum sludge found to have a slight effect on the using of sludge as fertilizer. Finally, SVI values for secondary precipitated sludge decreased, which can solve the problems related to bulking in the secondary settling tanks.

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