Effluent treatment cementation

The traditional effluent treatment method in these factories tend to be settlement pits, w here coarse solids are allow ed to settle, sometimes w ith the aid of flocculent addition. Settled solids w ould be periodically dug out of the settlement pits, piled nearby and allow ed to drain back into the pit for further settlement of the runoff w ater. The W ater at the end of the settlement pit w ould then be allow ed to drain to tbul sew er or surface w ater usually w ith mineral acid dosing, to reduce the high pH caused by the lime in the cement, w hich can be as high as pH 13, In extreme, but not that uncommon situations, the w aste w ater is allow ed to flow untreated to surface w aters or allow ed to soak aw ay to the ground, causing immense pollution to the receiving w ater - be it... 

In the last example crossflow microfiltration has been chosen because a slurry of a specified concentration can be achieved, cement is added when this has been obtained [Empsall and Hebditch, 1994]. The ability of microfiltration to provide particle-free permeate, above a certain threshold, has lead to the adoption of skid-mounted crossflow filters for heavy metal effluent treatment, see Figure 10.25 [Metal Finishers Association, 1992]. 

Petroleum. Apart from its use ia petrochemicals manufacture, there are a number of small, scattered uses of lime ia petroleum (qv) production. These are ia making red lime (drilling) muds, calcium-based lubricating grease, neutralization of organic sulfur compounds and waste acid effluents, water treatment ia water flooding (secondary oil recovery), and use of lime and pozzolans for cementing very deep oil wells. 

Beaven, G.W., Cross, J.E., Hooper, E.W., Study of the Behaviour of Inorganic Ion Exchangers in the Treatment of Medium Active Effluents. Part V. The Encapsulation of Inorganic Ion Exchangers in Cement, Rep. AERE-G-4421, United Kingdom Atomic Energy Authority, Harwell (1988) Beeckman, J.W., Froment, G.F., Chemical Engineering Science, 35, 805 (1980)... 

Although traditionally these solutions are treated by the physico-chemical process of precipitation with lime, current efforts are directed to the selective recovery and separation of the metals Zn, Cd, and Pb for subsequent treatment by electrolysis (for Zn, Pb, Cu) or cementation by powder metallic zinc (for Cd). Those effluents with relatively low levels of metal ions cannot be treated efficiently by SX but can be treated by transforming the SX system into the corresponding SIR system. 

Medium and high activity waste is stored at the Cadarache Center. High activity waste consists mainly of parts from the nickel and steel reflector assemblies or from control-rod mechanisms and irradiation devices. These account for the major part of the total radioactivity (4800 TBq) which has been removed from the reactor. The liquid effluent produced by washing and decontaminating operations was transferred to the Liquid Waste Treatment Facility at Cadarache where it has been neutralized, concentrated by evaporation and encapsulated in bitumen or cement. Furthermore, on completion of the partial dismantling work, about 300 tons of material (steel and lead in particular) will been returned to service. Much of this will be turned into biological radiation shielding. 

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