CHE5055Z – Critical Synthesis on

“Approaches to biomass retention in a non-sterile environment”

Presented by: Tayana Raper

University of Cape Town >> 3 May 2023 >> - 2 -

Brief Background

Selection of articles

Chosen based on ‘quick read’

of content

Variety of topics for differing

opinions

Methods of selection

Avoided Google Scholar

Made use of subscribed

databases and journal searches

Critical Synthesis

Critical SynthesisUniversity of Cape Town >> 3 May 2023 >> - 3 -

Papers StudiedTitle Year Authors Journal Citations Impact

Factor

Production of PHA by activated sludge treating municipal wastewater: effect of pH, sludge retention time (SRT) and acetate concentration in influent

2003Chua A, Takabatake H, Satoh H, Mino T.

Water Research 91 5.389

Influence of sludge retention time on membrane fouling and bioactivities in membrane bioreactor system

2005 Han S, Bae T, Jang G, Tak T.

Process Biochemistry 88 2.983

Increasing PHA yields from Cupriavidus necator by using filtered digestate liquors 2013

Passanha P, Esteves S, Kedia G, Dinsdale R, Guwy A.

Bioresource Technology 0 5.172

Performance of a bioreactor with submerged membranes for aerobic treatment of municipal wastewater

2002

Rosenberger S, Kruger U, Witzig R, Manz W, Szewzyk U, Kraume M.

Water Research 201 5.389

Domestic Wastewater treatment using an anaerobic bioreactor coupled with membrane filtration

1999 Wed C, Huang X, Qian Y.

Process Biochemistry 48 2.983

Critical SynthesisUniversity of Cape Town >> 3 May 2023 >> - 4 -

Brief BackgroundMaximised by increasing SRT

Conversion of feed

Low substrate concentration

Why Biomass Retention?

High throughput flowrates

Strain on downstream purification

Soluble product

Critical SynthesisUniversity of Cape Town >> 3 May 2023 >> - 5 -

Similarities

Use of Membrane Reactor

Type of membrane reactor

Benefits of increased SRT

Disadvantages of increased SRT

Yes, along with sequencing batch reactors (SBRs)

Submerged Hollow fibre (differing pore sizes)

Higher sludge/biomass concentration

Membrane permeability is decreased

Treatment performance better than traditional wastewater plants

Increase in concentration of inorganics (endogenous residue)

Sung-Soo Han et al, S. Rosenberger et al and Cheng Weng et al all concurred about the use of membrane bioreactor systems, in conjunction with sequencing batch reactors

Diagram showing SBR with a membrane filter Rosenberger S et al (2002)

< Conference >University of Cape Town >> 3 May 2023 >> - 6 -

ContradictionsAdeline Chua et al and Pearl Passanha et al looked at producing PHA from activated sludge and digestate liquors respectively. Their approaches were less obvious, and different to other three authors.

Reactor type used Effect of Increased SRT

Fed batch reactor for formation of PHA

PHA production from activate sludge was higher, for lower SRT (3 days vs. 10 days). Chua A, et al

Passanha P. et al only looked at one 50 hour fermentation

Batch experimental setup used in Chua A. et al (2003).

< Conference >University of Cape Town >> 3 May 2023 >> - 7 -

Approach to Synthesis

Selection• Find appropriate

articles• Ensure reputable

Summarise

• Careful analysis of sub-topic

• Summary of findings

Compare and

Compile

• Use summary to collate information

• Highlight contradictions

• Identify areas needing work

< Conference >University of Cape Town >> 3 May 2023 >> - 8 -

Limitations• Biomass Retention is a broader sub-topic than expected.

• Most of the articles are of recently used approaches as opposed to traditional.

• Factor of sterility vs. non-sterility proved very difficult to find. Most articles didn’t mention much about this.

• Qualitative comparison due to varying methods used• Comparing general approaches not necessary specific details.

• Five papers is actually too few to get an accurate synthesis about biomass retention.

• More literature on traditional approaches should be found.

< Conference >University of Cape Town >> 3 May 2023 >> - 9 -

Thank you