Enhanced hydrogen production from anaerobically digested sludge using microwave assisted pyrolysis

A total of 25 municipal sewage treatment plants were sampled, 10 of which were resampled, to determine the quantity of phenolics in the sewage, final effluent and the anaerobically digested sludge using capillary GC/MS/DS/techniques. The study noted in decreasing order of frequency in raw sewage: phenol, pentachloro-phenol, dimethyl phenol, 3-methyl, 4-chlorophenol, 2,4,6-trichloro-phenol, 2,4-dichlorophenol, 2-nitrophenol, 2-chlorophenol, 2,4-dinitro-6-methylphenol and 2,4-dinitrophenol. The maximum concentration of phenol in sewage and sludge was 2800 ppb and 4460 respectively, while similar values for pentachlorophenol were 58 and 1200 ppb. Statistically calculated concentration reductions for phenol and dimethyl phenol were generally greater than noted for tri- and pentachlorophenol. Low decreases or increases were noted for monochlorophenol and especially for dichlorophenol as a result of the chloronation of the final effluent.

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Characterization of raw sludge, chemically modified sludge and anaerobically digested sludge in Hong Kong

Water Science & Technology ◽

10.2166/wst.1998.0095 ◽

1998 ◽

Vol 38 (2) ◽

pp. 25-32 ◽

Cited By ~ 2

Author(s):

C. W. Chu ◽

C. S. Poon ◽

R. Y. H. Cheung

Keyword(s):

Hong Kong ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Chemical Properties ◽

Primary Treatment ◽

Digested Sludge ◽

Total N ◽

Chemically Modified ◽

Anaerobically Digested Sludge

Chemically Enhanced Primary Treatment (CEPT) or Chemically Assisted Primary Sedimentation (CAPS) is being employed at the new sewage work on Stonecutters Island as part of the Strategic Sewage Disposal Scheme (SSDS) in Hong Kong. CAPS involves the use of chemical coagulants (such as lime or ferric chloride) to induce coagulation or flocculation and let these finely-divided particles form large aggregates (floc) so that they can settle out within a reasonable period of time. In this study, five sludge samples collected from different sewage treatment plants in Hong Kong were physically and chemically characterized. They were chemically modified sludge from Stonecutters Island (CAPS) raw sludge from Tai Po and Yuen Long Sewage Treatment Plant (STP) (rTP & rYL) and anaerobically digested sludge from Tai Po and Yuen Long STP (dTP & dYL). It was found that CAPS sludge was better than other 4 sludge samples in terms of settleability and dewaterability. CAPS sludge contained significant higher amounts (p<0.01) of extractable compounds than other sludges (except NO3− for dTP, NH4+ and PO43− for dYL). The concentration of total N and P in CAPS sludge were significantly higher (p<0.01) than other sludges (except dYL). The concentrations of total Cu, Pb, Ni, Cd, Cr and K in the CAPS sludge were also significantly higher (p<0.01) than other sludge samples. Most of the metals (Cr, Pb, Cr and Zn) in CAPS sludge were associated with the organically-bounded phase. It is concluded that there are significant differences in both physical and chemical properties between the chemically modified sludge and biological treated sludges.

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Bioleaching of toxic metals from anaerobically digested sludge without external chemical addition

Water Research ◽

10.1016/j.watres.2021.117211 ◽

2021 ◽

pp. 117211

Author(s):

Zhiyao Wang ◽

Gaofeng Ni ◽

Jun Xia ◽

Yarong Song ◽

Shihu Hu ◽

...

Keyword(s):

Toxic Metals ◽

Digested Sludge ◽

Anaerobically Digested Sludge

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through tubing and fittings made of PTFE. Analysis was undertaken by the Warren Spring Laboratory of the Department of Trade and Industry, according to the method described by Bailey and Bedbo rough The results are shown in Table IV. and plotted in Fig. 3. and 4. Table IV. Variation of odour strength of extracted samples with volune of eluted air Volume of air Strength of odour samples passing through (dilutions) sludge before sampling (1/1) Raw sludge Digested sludge 0 154 000 9 900 11.1 53 000 350 22.2 30 600 270 55.6 15 500 190 111 8 200 160 It is clear from these results that there is considerable die-off of odour strength with time, and that, as would be expected, the anaerobic digestion of sludge can reduce the odour potential by at least one order of magnitude. To illustrate the importance of this die-off effect, the results have been re-plotted in Fig. 5. in a cunulative form; that is to say as cumulative percentage of the eventual colour release against volume of air. In the case of the raw sewage sludge, 38% of the ultimate odour was carried in the first odour sample, and 90% of the odour had been extracted by the passage of about 200 1. In the case of the anaerobically digested sludge, the same effect is much more marked; 72% of the ultimate odour was carried by the first sample, and thereafter the strength of the odour fell off very rapidly. There are two possible explanations for this. First, it can be postulated that as it is known that many of the important odorous chemical species are highly volatile, they may be only physically trapped in the sludge, and need little encouragement to transfer to the atmosphere. An alternative explanation concerns the existence of two equilibria. As the vapour/liquid equilibrium is disturbed by the passage of air, the concentration of dissolved compounds in the liquid phase falls, disturbing the ’solid’/liquid equilibrium The kinetics of transfer across this latter phase boundary are much slower than for the liquid/vapour transfer, so that the extraction of odour becomes limited by the rate of diffusion into the liquid phase. Two observations may be cited as evidence for this latter view. First, when sludge is applied to land, there is a rapid tail-off of odour nuisance after spreading. Hie incidence of rain after a dry period is known to result in an increased evolution of odour. Second, in earlier experiments samples of sludge were centrifuged, and the supernatant liquor discarded and replaced by tap water, before being used in the standard odour potential test. Some re-extraction of odour from the samples was rapidly found. In practice, both postulated mechanisms are probably at work, especially if the concept of ’solid/liquid equilibrium’ be extended to

Odour Prevention and Control of Organic Sludge and Livestock Farming ◽

10.1201/9781482286311-64 ◽

1986 ◽

pp. 152-152

Keyword(s):

Liquid Phase ◽

Tap Water ◽

Chemical Species ◽

Liquid Equilibrium ◽

Digested Sludge ◽

Order Of Magnitude ◽

Anaerobically Digested Sludge ◽

Solid Liquid ◽

Kinetics Of ◽

Potential Test

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Supplementation of KOH to improve salt tolerance of methanogenesis in the two-stage anaerobic digestion of food waste using pre-acclimated anaerobically digested sludge by air-nanobubble water

Bioresource Technology ◽

10.1016/j.biortech.2021.126360 ◽

2021 ◽

pp. 126360

Author(s):

Tingting Hou ◽

Jiamin Zhao ◽

Zhongfang Lei ◽

Kazuya Shimizu ◽

Zhenya Zhang

Keyword(s):

Anaerobic Digestion ◽

Salt Tolerance ◽

Food Waste ◽

Two Stage ◽

Digested Sludge ◽

Anaerobically Digested Sludge

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Impact of molecular structure and charge property of chitosan based polymers on flocculation conditioning of advanced anaerobically digested sludge for dewaterability improvement

The Science of The Total Environment ◽

10.1016/j.scitotenv.2019.03.156 ◽

2019 ◽

Vol 670 ◽

pp. 98-109 ◽

Cited By ~ 11

Author(s):

Weijun Zhang ◽

Huidi Wang ◽

Liqing Li ◽

Dandan Li ◽

Qiandi Wang ◽

...

Keyword(s):

Molecular Structure ◽

Digested Sludge ◽

Charge Property ◽

Anaerobically Digested Sludge

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Total nitrogen removal from high-strength ammonia recycle stream using a single submerged attached growth bioreactor

Water Science & Technology ◽

10.2166/wst.2007.242 ◽

2007 ◽

Vol 55 (8-9) ◽

pp. 59-65 ◽

Cited By ~ 1

Author(s):

A. Onnis-Hayden ◽

P.B. Pedros ◽

J. Reade

Keyword(s):

Total Nitrogen ◽

Nitrogen Removal ◽

Removal Rate ◽

Treatment Plant ◽

High Strength ◽

Nitrogen Loading ◽

Digested Sludge ◽

Attached Growth ◽

Anaerobically Digested Sludge ◽

Total Nitrogen Removal

An experimental study investigating the nitrogen removal efficiency from the recycle stream generated in the dewatering facility of the anaerobically digested sludge at the Deer Island wastewater treatment plant (WWTP) in Boston was conducted using a single submerged attached growth bioreactor (SAGB), designed for simultaneous nitrification and denitrification. The applied nitrogen loading to the reactor ranged from 0.7 to 2.27 kg-N/m3·d, and the corresponding total nitrogen (TN) removal rate ranged from 0.38 to 1.8 kg-N/m3·d. The observed nitrification rates varied from 0.42 kg-N/m3·d to 1.45 kg-N/m3·d with an ammonia load of 0.5 kg-N/m3·d and 1.8 kg-N/m3·d, respectively. An average nitrification efficiency of 91% was achieved throughout the experiment. Denitrification efficiency varied from 55%, obtained without any addition of carbon source, to 95% when methanol was added in order to obtain a methanol/nitrate ratio of about 3 kg methanol/kg NO3−-N.

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