Simulation analysis of ASM/Takács models in the BSM1 configuration.

The present paper summarizes the outlines of a simulation analysis study conducted on the BSM1 (formerly the COST benchmark) configuration using activated sludge models (ASM1, ASM2d and ASM3) coupled to Takács settler model. The prime objective was to develop reliable simulation software programs to implement these complex models according to the working conditions of a realistic plant. The analysis focused on comparing the steady state predictions of models ASM1/ ASM3 when imposed to pulse/ step type disturbances on wastewater characteristics and control variables, then on assessing the capability of the simulated configuration for bio-P removal using model ASM2d. Section 1 of the paper briefly presents problem definition/ solution approach while section 2 demonstrates some examples showing the main indications of the simulation analysis. ASM1/ ASM3 predictions indicate the presence of some significant differences between both models that could be related to their underlying concepts. ASM2d simulations show that adverse effects on the permissible limit of effluent's ammonia concentration should be expected when the plant is operated to achieve dual nutrient removal.

Combined effects of cadmium and zinc on both sequencing batch reactor and continuous activated sludge.

This study aims to investigate the performance and treatment capability of sequencing batch reactor and activated sludge systems under heavy metals shock loads. The combined effects of cadmium and zinc on both systems were studied. Two pilot plant units, one for each system were used to study the effect of gradually increasing both cadmium and zinc on the treatment process. Batch tests were also performed to study the effect of both cadmium and zinc shock loads on the acclimated sludge that collected from each pilot plant. The results of the pilot plant units showed that the efficiency of COD removal decreases under the gradual increase of heavy metals and that this efficiency was higher in the sequencing batch reactor pilot plant than the activated sludge pilot plant. Results of batch tests showed that the efficiency of COD removal of acclimated sludge collected from each pilot plant was higher than the normal sludge collected from both systems before adding metals. Similarly this efficiency was higher in the sequencing batch reactor pilot plant than the activated sludge pilot plant operated under the same conditions.

ASExpert: an integrated knowledge-based system for activated sludge plants.

The activated sludge process is commonly used for secondary wastewater treatment worldwide. This process is capable of achieving high quality effluent. However it has the reputation of being difficult to operate because of its poorly understood biological behaviour, variability of input flows and the need to incorporate qualitative data. To augment this incomplete knowledge with experience, knowledge-based systems were introduced in the 1980s however they didn't receive much popularity. This paper presents the Activated Sludge Expert system (ASExpert), which is a rule-based expert system plus a complete database tool proposed for use in activated sludge plants. The paper focuses on presenting the system's main features and capabilities to revive the interest in knowledge-based systems as a reliable means for monitoring plants. Then it presents the methodology adopted for ASExpert validation along with an assessment of testing results. Finally it concludes that expert systems technology has proved its importance for enhancing performance, especially if in the future it is integrated to a modern control system.