Features - Process biology

Screenshot from the LynxASM1 CAE software package

Designing and managing wastewater treatment plants using CAE software − the LynxASM1 modelling and simulation tool

Ever more versatile and sophisticated options for designing and managing plants are being developed. And as the new CAE tools become more accessible and widespread, suppliers continue to develop and refine the tools, so the reliability of their predictions increases – promoting further take-up.

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Process biology | Feasibility, optimisation and costs | Pre-treatment and post-treatment | Water quality and treatability

Fig. 1: Zeta potential distribution of membrane samples as a function of pH

The impact of biofouling on surface membrane properties in MBRs

MBR membranes are prone to fouling generally, and biofouling in particular, by organic matter originating from the microbial cells. These biofoulants vary in concentration with the activated sludge characteristics, such as the mixed liquor suspended solids (MLSS) concentration and solids retention time (SRT) (and so the food/microorganism (F/M) ratio), as well as the feedwater chemistry.

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Membrane operation | Process biology

Long-term monitoring of its constitution in the full-scale MBR

Reducing process aeration energy consumption in MBRs

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.

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Membrane operation | Process biology | Feasibility, optimisation and costs

OPEX vs flux at various membrane life periods

MBR OPEX − the theory of running costs

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.

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Membrane operation | Process biology | Feasibility, optimisation and costs

Filamentous intersections

Foaming in MBRs: measurement and evaluation

Foaming of conventional activated sludge (CAS) is very common. It may happen during start-up due to the presence of surfactants, with insufficient biomass to degrade them during the early stages. However, this is normally a short-term issue. These foams (from surfactant foaming) are mostly white and can be countered with anti-foamants until there are sufficient biomass developed to degrade them.

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Process biology | Feasibility, optimisation and costs

Islamorada WWTP

A decade of simultaneous nitrification and denitrification experience in MBR applications

Biological nitrogen removal from wastewater typically happens through aerobic nitrification (from ammonia to nitrate) and anoxic denitrification (nitrate to nitrogen gas). This is usually carried out in two separate process tanks other than in a sequencing batch reactors (SBRs). However, it is more energetically efficient to convert ammonia directly to nitrogen gas, since it requires less oxygen.

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Process biology