Organic matter release from primary sludge by mechanical cutting

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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Preliminary Investigation of Primary Sludge Hydrolysis

Proccedings of 10th International Conference "Environmental Engineering" ◽

10.3846/enviro.2017.076 ◽

2017 ◽

Author(s):

Regimantas Dauknys ◽

Aušra Mažeikienė ◽

Anna Haluza ◽

Illia Halauniou ◽

Victor Yushchenko

Keyword(s):

Organic Matter ◽

Retention Time ◽

Nutrient Removal ◽

Preliminary Investigation ◽

Biological Nutrient Removal ◽

Primary Sludge ◽

Sludge Retention Time ◽

Hydrolysis Process ◽

Sludge Hydrolysis ◽

Hydrolysis Of

One of reasons of non-effective biological nutrient removal from wastewater is lack of readily biodegradable organic matter. This problem could be solved by application of sludge hydrolysis process. The conditions for hydrolysis of primary sludge could be created performing the recirculation of the primary sludge and ensuring the required sludge retention time. In the period of preliminary investigation, the following conditions were created in the primary sedimen-tation tank of Vitebsk WWTP: average sludge recirculation was 4.8 % of the inlet flowrate to the sedimentation tank and average SRT was 5 days. Obtained results showed that hydrolysis process allowed improving the ratio between organic matter and nutrients in wastewater.

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Thermal pre-treatment of primary and secondary sludge at 70 °°C prior to anaerobic digestion

Water Science & Technology ◽

10.2166/wst.2005.0512 ◽

2005 ◽

Vol 52 (1-2) ◽

pp. 161-166 ◽

Cited By ~ 53

Author(s):

I.V. Skiadas ◽

H.N. Gavala ◽

J. Lu ◽

B.K. Ahring

Keyword(s):

Organic Matter ◽

Anaerobic Digestion ◽

Low Cost ◽

Methane Recovery ◽

Primary Sludge ◽

Thermophilic Anaerobic Digestion ◽

Secondary Sludge ◽

Thermophilic Digestion ◽

Pre Treatment ◽

Digestion Step

In general, mesophilic anaerobic digestion of sewage sludge is more widely used compared to thermophilic digestion, mainly because of the lower energy requirements and higher stability of the process. However, the thermophilic anaerobic digestion process is usually characterised by accelerated biochemical reactions and higher growth rate of microorganisms resulting in an increased methanogenic potential at lower hydraulic retention times. Furthermore, thermal pre-treatment is suitable for the improvement of stabilization and could be realized at relatively low cost especially at low temperatures. The present study investigates the effect of the pre-treatment at 70 °C on thermophilic (55 °C) anaerobic digestion of primary and secondary sludge in continuously operated digesters. Thermal pre-treatment of primary and secondary sludge at 70 °C enhanced the removal of organic matter and the methane production during the subsequent anaerobic digestion step at 55 °C. It also greatly contributed to the destruction of pathogens present in primary sludge. Finally it results in enhanced microbial activities of the subsequent anaerobic step suggesting that the same efficiencies in organic matter removal and methane recovery could be obtained at lower HRTs.

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Utilising laboratory experiments as a first step to introduce primary sludge hydrolysis in full-scale

Water Science & Technology ◽

10.2166/wst.2008.227 ◽

2008 ◽

Vol 57 (9) ◽

pp. 1397-1403 ◽

Cited By ~ 3

Author(s):

K. Jönsson ◽

A. Pottier ◽

I. Dimitrova ◽

U. Nyberg

Keyword(s):

Organic Matter ◽

Wastewater Treatment ◽

Carbon Source ◽

Laboratory Tests ◽

Laboratory Experiments ◽

Treatment Plant ◽

Full Scale ◽

Soluble Organic Matter ◽

Primary Sludge ◽

Sludge Hydrolysis

Laboratory experiments have been utilised as a tool to determine the possible yield of soluble COD and VFAs from settled influent and preprecipitated sludge at Klagshamn wastewater treatment plant and to determine the degradability of the organic matter. The release of ammonium and orthophosphate from the hydrolysed sludge has been estimated. It is possible to produce soluble organic matter of good quality from settled influent and preprecipitated sludge at Klagshamn WWTP. Denitrification rates of 3.1 mg NO3-N/(g VSS × h) were found for the hydrolysate in laboratory tests. Owing to the low phosphate concentrations in the hydrolysate from preprecipitated sludge, it shows a potential for postdenitrification despite stringent phosphorus outlet demands. Calculations based on data gained from the laboratory experiments show that about 50% of the external carbon source used today can be saved with minor changes in the plant operation except that the hydrolysis has to be established. Based on these findings, full-scale experiments with internal hydrolysis in the primary clarifiers were scheduled in one of the two lines at Klagshamn WWTP for the summer of 2007.

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