Anaerobic pre-treatment of sewage under low temperature (15 [degrees] C) conditions in an integrated UASB-digester system

The main objective of this thesis was to amend the UASB by the means of incorporating a digester for anaerobic sewage treatment in the Middle East region.A literature search of the various parameters that mightaffect the solid liquid separation process by filtration through the sludge bed of a UASB has been elaborated. The overall output of this study includes, literature review, structuring this field of science and highlighting fields where research is needed.The investigation of sewage characteristics in Palestine revealed that the sewage is of high strength and low temperature during wintertime ca . 15 ºC. Accordingly, prediction based on model calculations revealed that the application of the one stage UASB reactor for sewage treatment in Palestine is only possible when designed at a HRT of more than 22 hours. Alternatively, a novel technology consisting of a Digester complementing a UASB, namely UASB-Digester system, was proposed.The results of primary sludge stabilisation in CSTRs revealed that the major achievement of sludge stabilisation occurred at SRT³10 and 15 days at process temperatures of 35 and 25 ºC, respectively. The sludge dewatering results showed the existence of optimal SRT at 20 and 15 days at process temperatures of 25 and 35 ºC, respectively. While, the sludge settling is not affected by digestion.Running a pilot-scale one stage UASB and a UASB-Digester system on sewage from the village of Bennekom, The Netherlands validated the technical viability of the UASB-Digester system. The UASB reactor was operated at an HRT of 6 hours and temperature of 15°C, the wintertime sewage temperature in Palestine, and the digester was operated at 35°C. The achieved removal efficiencies of total COD, suspended COD, colloidal COD and dissolved COD of respectively 66, 87, 44 and 30 in the UASB-Digester is significantly higher than the respectively 44, 73, 3 and 5 achieved in the one stage UASB and as high as those reported for tropical countries. The conversion in the UASB of the UASB-Digester system is substantially higher than in the one stage, viz. the percentage methanogenesis of the influent COD were 21 and 44% in the first and second systems, respectively. The sludge produced from the UASB of the UASB-Digester system is substantially lower and more stable as compared with the sludge in the one stage UASB reactor. The settleability of the sludge of the UASB, UASB of the UASB-Digester system and the digester sludges reveals high settleability with no influence of the digestion conditions. The wasted sludge from the UASB of the UASB-Digester system is better dewaterable as compared to that of the UASB reactor.

Bibliographic Details

Main Author:	Mahmoud, N.J.A.H.
Other Authors:	Lettinga, G.
Format:	Doctoral thesis biblioteca
Language:	English
Subjects:	anaerobic treatment, palestine, sewage sludge, anaërobe behandeling, palestina, rioolslib,
Online Access:	https://research.wur.nl/en/publications/anaerobic-pre-treatment-of-sewage-under-low-temperature-15-degree
Tags:	Add Tag No Tags, Be the first to tag this record!