Dilution, sludge-filtrate

With regard to chemical use -diluted ferric chloride solutions (10% to 20%) usually give better results in the conditioning of the sludge. A high calcium lime is preferable or sludge filtration work. One should avoid excessive use of chemicals. The quantities of chemicals used for conditioning can be frequently reduced by careful control of the... 

Figure 7. Solids retention hy Nuclepore membranes loaded with a 100 1 dilution of sludge with sludge filtrate ((D) 1.0 pm (A) 8.0 pm)...

Thus, from sludge concentration c and the weight of a wet cake per kg of dry cake solids, x can be determined. If the suspension is dilute, then c is small and the product of m X c is small. This means that x will be almost equal to c. Since x depends on the product me, at relatively moderate suspension concentrations this effect will not be great and thus may be neglected. However, for the filtration of concentrated sludges, the mentioned phenomena will play some role, i.e., at constant feed the filtrate changes with time. 

In order now to remove proteins from the thin sludge it is vigorously stirred with 0-05 A-acetic acid in amount just sufficient to change the colour of methyl red (pH=4) (test with a sample), and is then filtered as above after shaking with a little kieselguhr if necessary. The filtrate is made neutral to litmus with dilute ammonia and in this condition, protected by a little toluene, can be kept unchanged for several days. 

In a recent document [25] presenting techniques adopted by the French for pollution prevention, a new process modification for steam segregation and recycle in phosphoric acid production is described. As shown in Figure 9, raw water from the sludge/fluorine separation system is recycled to the heat-exchange system of the sulfuric acid dilution unit and the wastewater used in plaster manufacture. Furthermore, decanted supernatant from the phosphogypsum deposit pond is recycled for treatment in the water filtration unit. The claim was that this process modification permits an important reduction in pollution by... 

The filtrate is diluted with 60 1. of cold water (Note 1) and allowed to stand overnight. The brown sludge is filtered with suction (Note 2) and pressed as dry as possible on the funnel. After drying, it weighs about 164 g. The combined precipitates are refluxed for thirty minutes each with successive 650-, 500-, and 500-cc. portions of chloroform. The chloroform extracts are filtered while hot, and. the bright red filtrates are combined and concentrated to a volume of 500 cc. by distillation. One liter of petroleum ether (b.p. 60-90°) is added, whereupon the crude 2-nitro-6-methoxybenzonitrile separates as a red powder. It is removed by filtration and air-dried. It weighs 120-125 g. (22 23 per cent of the theoretical amount) and melts at 148-157° (Note 3). It is used without purification (Note 4). 

Fig. 8-13. Separation of inorganic anions in the filtrate of a neutral sludge. — Separator column IonPac AS4A eluent 0.0017 mol/L NaHCC>3 + 0.0018 mol/L NajCCb flow rate 2 mL/min detection suppressed conductivity injection 50 pL sample (1 250 diluted).

EPA Method 3050 is a procedure for aeid digestion of sediments, sludges, and soils. A sample of up to 2 g is treated with a mixture of nitric acid and hydrogen peroxide the sample is then refluxed with either con. HNO3 or con. HCl, then refluxed with dilute HCl, filtered, and the filtrate analyzed for metals. 

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