Assessment of Metal Mobility in Sludges and Solid Wastes

For the municipal solid waste (MSW) to be used in a proper way, it is necessary to implement clean technologies capable of thermal treatment of MSW and RDF in order to produce heat and electricity while meeting current ecological requirements. Nowadays, a number of technologies for MSW/RDF thermal treating are being used worldwide. Among them, the most proven technologies, applicable for industrial introduction, have been considered while analyzing their advantages/ disadvantages accounting for local conditions of Ukraine.

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New Systems for the Digestion of Solid Wastes

Water Science & Technology ◽

10.2166/wst.1992.0164 ◽

1992 ◽

Vol 25 (7) ◽

pp. 319-326 ◽

Cited By ~ 3

Author(s):

A. Wellinger ◽

U. Baserga ◽

K. Egger

Keyword(s):

Dry Matter ◽

Gas Production ◽

Matter Content ◽

Solid Wastes ◽

Dry Matter Content ◽

Feeding System ◽

Shear Forces ◽

Tank Reactor ◽

Strong Shear ◽

First Results

Two new systems for the digestion of solid wastes at thermophilic temperatures were developped and are currently being investigated at our research institute. The first system (ANCOM) was designed to process straw-rich cattle manure with a natural dry matter content of 18% to 22%. First results demonstrated a good specific gas production of 1.2 m3 biogas per m3 digester volume and day (54% methane) corresponding to a gas yield of 400 l per kg VS. A second digester system was developed to treat fruit, garden and vegetable (FGV-) waste. Because FGV-waste tends to float, a stirred tank reactor was designed in cooperation with an engineering firm. The reactor includes a distinguished new stirring system taking up strong shear forces and a hydraulic feeding system which guarantees that even during recirculation of the material, the hygenized digested substrate leaving the digester is not brought in contact with the fresh incoming material. First results measured at an HRT of 40 days demonstrated a specific gas production of 2.7 m3 per m3 fermenter and day.

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Metallic pollution in clogging materials of urban porous pavements

Water Science & Technology ◽

10.2166/wst.1995.0014 ◽

1995 ◽

Vol 32 (1) ◽

pp. 57-62 ◽

Cited By ~ 5

Author(s):

Valérie Colandini ◽

Michel Legret ◽

Yves Brosseaud ◽

Jean-Daniel Baladès

Keyword(s):

Heavy Metal ◽

Particle Size ◽

Road Traffic ◽

Total Concentration ◽

Extraction Procedure ◽

Interaction Strength ◽

Metal Mobility ◽

Residual Fraction ◽

Metal Contents ◽

Copper Zinc

Porous pavements infiltrated with stormwater are faced with clogging problems: runoff particles seep and clog the pervious surface layer of these structures. Clogging material samples (in the form of sludge) have been collected in cleaning operations on the pervious asphalt. This study aims at characterizing these materials, particle size distribution, heavy metal contents by particle size, and studying interactions between metals and particles. A sequential extraction procedure proposed by the experts of the Community Bureau of Reference (B.C.R.) was applied to provide information about heavy metal distribution on particles and to evaluate interaction strength, and consequently potential metal mobility when chemical variations occurred in the environment. Mainly made up of sand, the materials are polluted with lead, copper, zinc and cadmium. The concentrations appeared to be linked with road traffic intensity. The heavy metal contents by particle size showed that the finer are the particles, the higher are the heavy metal concentrations. Heavy metals were found potentially labile; metals contents in the residual fraction (mineral fraction) represented less than 20 % of the total concentration. Cadmium and zinc were apparently more labile than lead and copper.

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Conditioning of oily sludges with municipal solid wastes incinerator fly ash

Water Science & Technology ◽

10.2166/wst.1997.0318 ◽

1997 ◽

Vol 35 (8) ◽

pp. 231-238 ◽

Cited By ~ 7

Author(s):

Tay Joo Hwa ◽

S. Jeyaseelan

Keyword(s):

Heavy Metals ◽

Fly Ash ◽

Specific Resistance ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Solid Wastes ◽

Municipal Solid Wastes ◽

Capillary Suction ◽

Optimum Dosage

Conditioning of sludges improves dewatering characteristics and reduces the quantity of sludge to be handled. Anaerobic digested sludge collected from a sewage treatment plant contained 1.8% to 8% oil. The increase of specific resistance and capillary suction time (CST) with increasing oil content observed in these samples indicates the interference of oil in dewatering. It has been found that addition of municipal solid wastes incinerator fly ash decreases the specific resistances and capillary suction times of oily sludges rapidly up to 3% dosage. Beyond 3% fly ash, the decrease is less significant and the solids content in the sludge cake increases. This optimum dosage remains the same for sludges with varying oil contents from 1.8% to 12%. The total suspended solids of filtrate decreases with fly ash dosage but the toxic concentrations of heavy metals increases considerably. However at the optimum dosage of 3%, concentrations of heavy metals are within the limits for discharging into the sewers. The correlations of CST with the dewatering characteristics such as specific resistance, filter yield and corrected filter yield are established. These correlations can be used to obtain a quick prediction on dewaterability.

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