Primary sludge hydrolysis for biological nutrient removal

Abstract

Primary sludge hydrolysis can enrich primary effluent with the soluble organics which in turn can be a valuable carbon source to subsequent nutrient removal processes. By controlling hydraulic retention time and temperature it is possible to confine the anaerobic digestion of the primary sludge to the acidogenic and acetogenic phase (hydrolysis/fermentation process), and take advantage of the soluble organics produced. This paper presents the results of a research involving bench and pilot scale experiments related to primary sludge hydrolysis. The pilot scale sedimentation tank (4.10 m in diameter, 3.20 m in depth) operated over an expended period of 21 months as a conventional clarifier and following this as a fermentor unit employing sludge recirculation. Parallel to the pilot scale experiments, several batch and continuous flow bench scale experiments were conducted in order to determine the factors controlling the production of soluble organics and the effect of the latter on the denitrification process. The conclusions drawn were that a) a soluble COD production of the order of 5-6% in terms of sludge TCOD can be expected in a batch fermentor operating with HRT≅2days at T≤ 20°C, b) in a continuous flow fermentor, combinations of T>20°C and SRT>2 should be applied in order to achieve a production of the order of 10%, c) significant soluble carbon production can be achieved in primary sedimentation tanks (over 30% in terms of influent SCOD) when relatively increased SRTs (4 to 5 days) in combination with sludge recirculation are employed, under T>22°C, and d) increased denitrification performance of the order of 9 mgNOx/g MLSS.hr, can be achieved with hydrolysate as a carbon source.

The biological quantitative reduction experimental research on aerobic excess sludge in papermaking wastewater

“…The density of CH 4 and CO 2 gas are 0. 7168 g/L and gas 1.9769 g /L, respectively ,while the carbon content in them are 0.…”

“…The gas made by fermented Sludge is methane, which major components of CH 4 order to find that under the conditions of mesophilic digestion ,the relationship between organic content and decomposition rate,which can calculation of oretical gas production.…”

“…Most of them generate VFA by fermented and hydrolyzed the primary sedimentation sludge which come from Sewage Treatment Plant, others study the sludge mixed by primary sludge and excess sludge [3][4][5]. The majority of domestic research the acid hydrolysis of high concentration wastewater.There is little study about the sludge comes from municipal wastewater, directed at the treatment plant less acidogenic study [6], not to mention the sludge comes from papermaking.…”

Acid Fermentation of Primary Sludge Subjected to Sonication

“…Lotne kwasy tłuszczowe, a zwłaszcza kwas octowy (uzyskiwane w procesach fermentacji kwaśnej), stanowią najbardziej pożądaną i przyswajalną formę węgla organicznego. W procesach biologicznego oczyszczania ścieków zawartość łatwoprzyswajalnego węgla organicznego istotnie wpływa na szybkość i efektywność denitryfikacji i defosfatacji [1][2][3].…”

An investigation into the mechanism underlying enhanced hydrolysis of complex carbon in a biosulphidogenic recycling sludge bed reactor (RSBR)

“…Yields of soluble products, such as volatile fatty acids (VFA) and soluble sugars, can be affected by both environmental and operational parameters, and are usually low, with the average being less than 20% (WhittingtonJones, 2000). The maximum reported yield from hydrolysis of PS under methanogenic conditions is approximately 35% at 24 o C (Hatziconstantinou et al, 1996).…”