A wastewater treatment using a biofilm airlift suspension reactor with biomass attached to supports: a numerical model

Abstract

A mathematical model of the biological process occurring in a modified biofilm airlift suspension reactor is presented. When compared with a traditional wastewater treatment plant, a biofilm airlift suspension process has major advantages, such as higher oxygen levels in the bulk fluid and lower space requirements. The limited volumes obtained with this technique generally do not allow to reach the high times of contact required for an efficient removal of nitrogen that normally are characterized by a slower kinetics than carbonaceous compounds. To avoid this problem, supports for attached biomass growth were inserted in the reactor. Both physical and biological aspects were incorporated into the presented model to simulate the removal processes of the substrates. A sensitivity analysis was performed, and the model was validated using experimental results obtained at a lab-scale plant. This model can accurately estimate the removal rate in different boundary conditions providing the details of the water quality profiles through the reactor and in the attached biomass. The model thus represents a valid aid for design purposes and for the management of treatment plants that use these uncommon reactors. The model also provides the required hydraulic retention time for a complete nitrification and the appropriate recirculation ratio. The results have shown the full-scale applicability of this treatment due to its efficiencies coupled to the advantages of its low impact, low space requirement and low sludge production.

Factors Affecting Spatial and Temporal Concentration Variability of Pharmaceuticals: Comparison between Two WWTPs

“…The aim is to give a picture of possible concentration variations in time and their variations as influenced by the main driving forces [45]. This is particularly important since WWTP effluents are often considered and modeled as steady emissions (such as the model GREATER, [46]).…”

A review on the advances in nitrifying biofilm reactors and their removal rates in wastewater treatment

“…In these cases, biofilms can represent an effective solution to successfully retain biomass in the reactors . Several technologies based on the biofilm have been developed as alternatives to the traditional wastewater treatment . Biofilm reactors represent the primary means to harness the usefulness of biofilms for water treatment, such as N removal .…”

“…Biofilm processes are commonly used for nitrification . In recent years, many systems have been tested and applied, mainly for industrial wastewater, to pilot and full‐scale plants, such as MBBRs, sequencing biofilm batch reactors and membrane bioreactors . Different types of nitrifying bioreactors are summarized in Table .…”

“…22 Several technologies based on the biofilm have been developed as alternatives to the traditional wastewater treatment. 23,24 Biofilm reactors represent the primary means to harness the usefulness of biofilms for water treatment, such as N removal. 25 For instance, Zekker et al reported that biological N removal efficiency in moving-bed biofilm reactors (MBBRs) is dependent on temperature and toxic nitrite concentrations.…”

“…28 In recent years, many systems have been tested and applied, mainly for industrial wastewater, to pilot and full-scale plants, such as MBBRs, sequencing biofilm batch reactors and membrane bioreactors. 24,29 Different types of nitrifying bioreactors are summarized in Table 1. This review will discuss the most widely used nitrifying bioreactor systems in recent decades which have been proven to be very efficient.…”