Although a number of studies have compared the MBR system performance with that of the conventional or classical activated sludge (CAS) process in treating municipal wastewater, none have attempted a simultaneous comparison of their environmental, techno-economic and social acceptance aspects.
Feasibility, optimisation and costs | Alternative membrane technologies and applications
MBRs use more energy compared with classical activated sludge (CAS) because the aeration requirements are greater. Aeration is needed both for the biological and membrane tanks for degrading the organics and scouring the membrane respectively. Typically, aeration energy consumption accounts for 70–80% of total energy used for the municipal wastewater treatment process, with 40–60% consumed by the process biology.
Membrane operation | Process biology | Feasibility, optimisation and costs
A study carried out by Andrade and co-authors assessed the viability of a two-stage membrane bioreactor−nanofiltration scheme (MBR−NF) for treating dairy wastewater. Of key concern was the quality of the treated water with respect to its potential reuse and the overall cost of the scheme.
Feasibility, optimisation and costs | Pre-treatment and post-treatment | Water quality and treatability
China features many of the largest municipal wastewater MBRs in the world. Apart from their capacity, some also are ambitious in their construction. The below-ground installation at Kunming City, commissioned in 2012, is one such example. At an ADF (average daily flow) capacity of 150,000 m3/d and a peak daily flow of 195,000 m3/d, it is a substantial plant.
Membrane operation | Feasibility, optimisation and costs | Pre-treatment and post-treatment | Water quality and treatability
Operational costs in MBRs are marginally higher than those of conventional activated sludge (CAS). Firstly, permeating water through a membrane demands energy. In the case of the immersed technologies (iMBRs) this means that the overall specific aeration demand (SAD) is higher, since air is needed both for maintaining the process biology in the aeration tank and scouring the immersed membrane.
Membrane operation | Process biology | Feasibility, optimisation and costs
Last year, we asked 'What’s the main issue with MBRs?' This time our question focused on the topic of sludge − most of your responses from the previous three surveys had been based around this topic so we felt it was worthy of further investigation.
