Sedimentation with digested sludges

Sedimentation Experiments with Digested Sludges. Sedimentation experiments were made to observe the settling behavior after dilution... 

Fernandez et al. [9] used supercritical fluid extraction combined with ion pair liquid chromatography to determine quaternary ammonium in digested sludges and marine sediments. Carbon dioxide modified with 30% methanol was used as the extractant at an operating pressure of 380atm. Between 0.2 and 3.7g kg-1 surfactant was found in Swiss works effluent sludges, determined with a relative standard deviation of 7%. 

Laboratory and full scale experiments have been made with activated and digested sludge from the Central Waste-Water Treatment Plant in Prague. Laboratory experiments in a steel pipe of 32 mm diameter and full scale experiments were performed in a cast iron pipe of diameter 250 mm used for sludge transport from the Prague Central Plant to the sedimentation fields, Fig. 2, when maximum drag reduction was 15 - 20 %... 

Another study has reported that poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) was extensively mineralized in digester sludge, septage sediments, and landfill reactors, with half-lives less than 30 d (27). 

Thus, LAS and secondary alkane sulfonates (SAS) are extracted from sewage sludges in the form of tetrabutylammonium ion pairs [47]. Lee and Peart extracted NP from sewage sludge spiked with acetic anhydride and a base with supercritical CO2. In this way NP is, in situ, converted into its acetyl derivative [48]. Ditallowdimethylammonium chloride (DTDMAC) is quantitatively extracted from digested sludges and marine sediments using supercritical CO2 modified with 30% methanol [49]. 

Fernandez, R, A. C. Alder, M. J. F. Suter, W. Giger, Ditallowdimethylammonium in digested sludges and marine sediments by supercritical fluid extraction and LC with post-column ion-pair extraction. Anal. Chem., 1996,68, 921-929. 

Jensen et al. [45] applied the method described in section 9.1.2.1 for the determination of DDT and polychlorobiphenyls in sulphur containing sediments to the analysis of sludges. The results in Fig. 9.7 show the beneficial effects of pretreatment of the sewage with tetrabutyl ammonium sulphate-sodium sulphite reagent on the recovery of DDT and polychlorobiphenyls from a digested sewage sludge sample. 

Surfactants such as LAS and NPEO have been found in compartments with low oxygen content, such as anaerobic sludge digesters or anaerobic continental and marine sediments [14,15,18-25]. One of the possible causes of this persistence is the inhibition of the anaerobic digestion [17,26,27]. Battersby and Wilson [27] observed inhibitory effects of NP at 50 mg CL-1 on methane formation in a survey of the anaerobic biodegradation potential of organic chemicals in digesting... 

Alternatively, plain sedimentation basins with mechanical equipment for continuous collection of the fresh sludge may be used. The fresh sludge, so collected, is discharged into separate sludge digestion tanks which operate on the principle of the lower story of the Imhoff tank except that by means of higher and better temperature control the digestion cycle is much more rapid and efficient than for the Imhoff tank. 

Metal and metalloid pollutant analysis of environmental matrices may be conducted with several elemental analysis techniques. For analysis to be possible, all matrices, including unfiltered groundwater, leaching procedure extracts, industrial and organic wastes, soils, sludges, and sediments must be digested with acid. Exceptions are... 

Industrial wastes, soils, sludges, sediments, and other solid wastes (total chromium) Digest with nitric acid/hydrogen peroxide ICP-AES 4.7 pg/L 101% at 3.75 mg/L EPA 1996b (Method 6010)... 

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