Experimental Validation of a Model Describing the Cycle of Nitrogen in a Step Sludge Recirculation Activated Sludge System With Denitrification

Abstract

In this paper, a model describing the cycle of nitrogen in a Step Sludge Recirculation (SSR) reactor, was developed. The SSR reactor is a multistage, continuous stirred tank reactor where the recycled biomass is distributed over all stages. The SSR system provides a uniform treatment of the wastewater and high purification efficiency for both carbon and nitrogen removal. The objective of this work was to develop a mathematical model of the SSR system, based on the analysis of various parameters that are present in the system. The simplified form of the IWA-ASM model was adapted to include the carbon removal, nitrification and denitrification processes. For model validation, a SSR pilot plant fed with synthetic wastewater was operated for approximately four months. The experimental results show that the SSR system seems to be appropriate to attain maximum TOC and nitrogen removal with minimum sludge production. The proposed model seems to be capable of expressing the behavior of carbon removal, nitrification, denitrification and various microorganism species in a SSR configuration of a nitrogen cycle. When the experimental results were compared with those estimated by the proposed model, the model predictions matched well with the experimental results.

On The Relationship between Suspended Solids of Different Size, the Observed Boundary Flux and Rejection Values for Membranes Treating a Civil Wastewater Stream

“…This increase of performances was attributed to the establishment of an optimal distribution of microorganisms along the reactor, thus favoring substrate degradation in the first stages and predation in the latter stages. In addition, an increase of sludge settleability was observed [ 17 ].…”

“…In this work, the fouling of membranes treating the effluent of a step sludge recirculation (SSR) activated sludge process treating municipal wastewater was investigated. With respect to conventional activate sludge reactors, the SSR system has been proved to achieve higher carbon and nitrogen removal with minimum sludge production, whose disposal of represents one of the crucial issues in wastewater management [ 17 , 18 ].…”