Dissolved organic matter byproducts from combined low-level alkaline and mechanical treatment of sludge: species, and their bioavailability

Abstract Low-level alkalinity (pH 9–10) coupled with ultrasonic or mechanical cutting with different energy input for obtaining carbon sources were tested for sludge pretreatment process before anaerobic sludge digestion. The differences between the primary sludge (PS) and waste activated sludge (WAS)-derived DOM species were evaluated for their bioavailability and affinity (in the form of amino acids) to the bio-nutrient removal (BNR) biomass. Soluble microbial by-product-like substances as the predominant DOM components in the raw PS and WAS increased by 23 and 22%, respectively, after low-level alkaline treatment (pH 9–10) and ultrasonication. In addition, the protein components were degraded further as free amino acids (FAAs). The sludge-derived aspartate, glutamate, followed by arginine were most commonly used FAAs by the BNR biomass. The pattern of recovering this special sludge-derived carbon source to enhance P removal and recovery in the BNR process is depicted.

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Up-to-date modification of the anaerobic sludge digestion process introducing a separate sludge digestion mode

Water Science & Technology ◽

10.2166/wst.2001.0604 ◽

2001 ◽

Vol 44 (10) ◽

pp. 143-147 ◽

Cited By ~ 8

Author(s):

K. Sato ◽

S. Ochi ◽

M. Mizuochi

Keyword(s):

Sewage Treatment ◽

Anaerobic Sludge ◽

Advanced Treatment ◽

Treatment Mode ◽

Primary Sludge ◽

Sewage Treatment Plants ◽

Advantages And Disadvantages ◽

Digestion Process ◽

Sludge Digestion ◽

Anaerobic Sludge Digestion

Sewage treatment plants in Japan are subjected to advanced treatment to remove nutrients and hence control eutrophication problems in lakes and bays. This paper discusses the advantages and disadvantages of the separate digestion treatment mode for sludge generated from advanced wastewater treatment. In the separate digestion only primary sludge is digested and the excess activated sludge is directly dewatered. Separate digestion can reduce the return load of nutrients to approximately one third, and has major potential for the beneficial use of sludge.

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THE IMPACT OF CHEMICAL PHOSPHORUS REMOVAL ON THE PROCESS OF ANAEROBIC SLUDGE DIGESTION

Mokslas - Lietuvos ateitis ◽

10.3846/mla.2010.094 ◽

2010 ◽

Vol 2 (5) ◽

pp. 71-74

Author(s):

Svetlana Ofverstrom ◽

Ieva Sapkaitė ◽

Regimantas Dauknys

Keyword(s):

Anaerobic Digestion ◽

Phosphorus Removal ◽

Biogas Production ◽

Anaerobic Sludge ◽

Primary Sludge ◽

Sludge Digestion ◽

Volatile Solids ◽

Anaerobic Sludge Digestion ◽

Gas Volume ◽

The Impact

The paper investigates the efficiency of the mixture of primary sludge and excess activated sludge in Vilnius WWTP with reference to the anaerobic digestion process. Sludge digestion was carried out under laboratory conditions using anaerobic sludge digestion model W8 (Armfield Ltd., UK). Laboratory analyses consist of two periods – the anaerobic digestion of the un-dosed and Fe-dosed sludge mixture. The results of digestion were processed using the methods of statistical analysis. The findings showed reduction in volatile solids approx. by 6% when dosing min FeCl3·6H2O and 15% when dosing max FeCl3·6H2O into feed sludge. Gas volume produced during the digestion of the un-dosed sludge was 90–160 ml/d and 60–125 ml/d in min Fe-dosed sludge and 45-95 ml/d. Also, correlation between VS loadings and biogas production was found. A rise in VS loading from 0,64 g/l/d to 1,01 g/l/d increased biogas production from 90 ml/d to 140–160 ml/d.

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Treating an aged pentachlorophenol- (PCP-) contaminated soil through three sludge handling processes, anaerobic sludge digestion, post-sludge digestion and sludge land application

Water Science & Technology ◽

10.2166/wst.2001.0606 ◽

2001 ◽

Vol 44 (10) ◽

pp. 149-156 ◽

Cited By ~ 3

Author(s):

S.-T. Chen ◽

P.M. Berthouex

Keyword(s):

Contaminated Soil ◽

Municipal Wastewater ◽

Treatment Plant ◽

Land Application ◽

Anaerobic Sludge ◽

Primary Sludge ◽

Sludge Digestion ◽

Anaerobic Sludge Digestion ◽

Soil Cleanup ◽

Sludge Application

The extensive pentachlorophenol (PCP) contamination and its increasing treatment costs motivate the search for a more competitive treatment alternative. In a municipal wastewater treatment plant, anaerobic sludge-handling processes comprises three bio-processes, namely the anaerobic sludge digestion, post-sludge digestion and sludge land application, which reduce sludge organic content and make sludge a good fertilizer for land application. Availability and effectiveness make the anaerobic sludge handling processes potential technologies to treat PCP-contaminated soil. The technical feasibility of using anaerobic sludge bioprocesses was studied by treating PCP soil in two pilot digesters to simulate the primary sludge digestion, in serum bottles to mimic the post-sludge digestion, and in glass pans to represent the on-site sludge application. For primary digestion, the results showed that up to 0.98 and 0.6 mM of chemical and soil PCP, respectively, were treated at nearly 100% and 97.5% efficiencies. The PCP was transformed 95% to 3-MCP, 4.5% to 3,4-DCP, and 0.5% to 3,5-DCP. For post-digestion, 100% pure chemical PCP and greater than 95% soil PCP were removed in less than 6 months with no chlorophenol residues of any kind. Complete removal of PCP by-products makes this process a good soil cleanup method. For on-site treatment, PCP was efficiently treated by multiple sludge application; however, the PCP residue was observed due to the high initial PCP content in soil. Overall, more mass PCP per unit sludge per day was processed using the primary sludge digestion than the on-site soil treatment or post-sludge digestion. And, sludge acclimation resulted in better PCP treatment efficiencies with all three processes.

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Acid and alkaline treatments for enhancing the growth of rhizobia in sludge

Canadian Journal of Microbiology ◽

10.1139/w01-033 ◽

2001 ◽

Vol 47 (6) ◽

pp. 467-474 ◽

Cited By ~ 20

Author(s):

Faouzi Ben Rebah ◽

Rajeshwar D Tyagi ◽

Danielle Prévost

Keyword(s):

Cell Count ◽

Sinorhizobium Meliloti ◽

Total Suspended Solid ◽

Alkaline Treatment ◽

Suspended Solid ◽

Wastewater Sludge ◽

Original Sample ◽

Primary Sludge ◽

Sludge Pretreatment ◽

Secondary Sludge

Wastewater sludges have been proposed as an effective media for the production of rhizobia. The effect of total suspended solid (TSS) concentrations and pretreatments of sludge on the growth of Sinorhizobium meliloti were investigated. Acid (pH 2.06.0 obtained with H2SO4) and alkaline (50200 mequiv.wt./L of NaOH) treatments were applied to enhance the biodegradability of primary (0.325%3.2% TSS obtained by dilution of original sample) and secondary (0.2%0.4% TSS obtained by concentration of original sample) sludges. In primary sludge without pretreatment, the highest cell count (11.10 × 109 cfu/mL) was obtained with 1.3% TSS. However, a maximum cell count of 13.00 × 109 cfu/mL was reached using an acid treatment of pH 2.0 and a 0.325% TSS concentration. Moreover, the alkaline treatment with 100 mequiv.wt./L of NaOH and 0.65% TSS increased the cell yield to 21.00 × 109 cfu/mL. For secondary sludge without pretreatment, no enhancement of growth was observed while increasing TSS concentration. This may be due to the increase of inhibitory substances, such as heavy metals, and of the Ca and Mg concentrations. As in primary sludge, some acid and alkaline treatments of secondary sludge tend to improve the cell count of S. meliloti. However, the highest value of 9.80 × 109 cfu/mL obtained with 0.4% TSS at pH 2.0 was lower than that obtained with primary sludge. It was also observed that S. meliloti grown in treated sludges maintained its capacity to nodulate alfalfa.Key words: wastewater sludge, rhizobium, inoculum, sludge pretreatment, nodulation.

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