Role of experimental support as an essential component of sustainable design of the activated sludge process for nitrogen removal

Abstract

Background This study evaluated the essential role of the experimental support as an integral component of process design for the nitrogen removal activated sludge process. This role was demonstrated in prescribing and implementing a relevant design procedure; a similar treatment plant at Ambarlı in Istanbul was selected to provide the necessary experimental support, which was derived from the sewage, lab‐scale experiments, and from the plant itself. Each step of the design included the relevant scientific and conceptual basis and was implemented using the necessary experimental data specifically generated from a selected wastewater source. Results The target was to compile experimental data that would be necessary for the study and be equally applicable to similar design or research activities elsewhere. This data included major wastewater characteristics, chemical oxygen demand (COD) fractionation, process kinetics for COD removal and nitrification, applicable sewage temperature, and details for the impact of primary settling on system performance. Conclusion This study developed a new design approach involving solely COD for both the substrate and biomass but expressing the related component per unit flow rate. This approach offered a template that is adjustable to any similar design by only requiring specific information on the sewage flow and sludge age. The entire design procedure was presented as supported by original experimental data and in a summarized algorithm format. The study also emphasized the selection of an appropriate anoxic volume. A revised empirical expression was suggested for the computation of the corresponding denitrification potential, which was also supported by process modelling; they both indicated that the current empirical approach generally defined an excessively large anoxic volume. © 2022 Society of Chemical Industry (SCI).

Anatomy of chemically enhanced sewage settling by particle size distribution analysis

“…In this context, the practical merit of the suggested treatment scheme should be discussed here, with due consideration of related significant constraints: The Yenikapı discharge is located within the historical peninsula of Istanbul, downstream of the southern outlet of the Bosphorus, with very limited space available for auxiliary treatment. The total volume of the treatment system with respect to the daily sewage flow treated, m 3 (m 3 d −1 ) −1 , best represented by the overall hydraulic retention time, θ HT , would help to visualize the relative space requirement of the alternatives on the table: while the θ HT level is less than 0.04 days for the chemically enhanced settling in this study, the same parameter is at least 0.125 days for the A process; on the other hand, the minimum θ H level of a nutrient removal activated sludge alternative would be in the range of 0.55–0.60 days, way over the above values 21 Istanbul is under a severe earthquake threat in the near future and the Yenikapı area is perhaps one of the most vulnerable spots.…”

“…The total volume of the treatment system with respect to the daily sewage flow treated, m 3 (m 3 d −1 ) −1 , best represented by the overall hydraulic retention time, ⊔ HT , would help to visualize the relative space requirement of the alternatives on the table: while the ⊔ HT level is less than 0.04 days for the chemically enhanced settling in this study, the same parameter is at least 0.125 days for the A process; on the other hand, the minimum ⊔ H level of a nutrient removal activated sludge alternative would be in the range of 0.55-0.60 days, way over the above values. 21 (2) Istanbul is under a severe earthquake threat in the near future and the Yenikapı area is perhaps one of the most vulnerable spots. Marine geological and geophysical studies conducted since the 1999 devastating Izmit earthquake in Turkey indicate that an earthquake with a magnitude over 7.5 may occur in the Marmara Sea at any time in a 30 year period following the Izmit earthquake.…”

“…A recent study provided a detailed demonstration that appropriate experimental support was a vital prerequisite for sustainable wastewater treatment 21 . Accordingly, the experiments were conducted on sewage collected at the effluent of the preliminary treatment facilities (screens and aerated grit chamber) at the Yenikapı marine outfall in order to provide a higher level of pollutant removal prior to discharge.…”

“…Probability distributions showing temporal variations of the concentration levels associated with the relevant quality parameters in the wastewater were evaluated by a simple method. The measured concentrations of a particular quality indicator ( C ) were arranged from lowest to highest and then the probability pCi was calculated as follows: Details on calculation of the 50 and 70 percentiles are given in Orhon et al 21 …”

“…A recent study provided a detailed demonstration that appropriate experimental support was a vital prerequisite for sustainable wastewater treatment. 21 Accordingly, the experiments were conducted on sewage collected at the effluent of the preliminary treatment facilities (screens and aerated grit chamber) at the Yenikapı marine outfall in order to provide a higher level of pollutant removal prior to discharge. The conventional wastewater characterization study was based on the measurement of total chemical oxygen demand (TCOD), soluble chemical oxygen demand (SCOD), TSS, volatile suspended solids (VSS), TN, ammonia nitrogen (NH 4 + -N), nitrate nitrogen (NO 3 − -N), TP, salinity and conductivity for more than 50 days.…”