Biofouling and me: My Stockholm syndrome with biofilms

https://espace.library.uq.edu.au/view/UQ:ffca634/UQffca634_OA.pdf

Improving wastewater management using free nitrous acid (FNA)

In order to optimize some operational conditions of MBR systems, a MBR pilot plant equipped with a submerged hollow fibre membrane module was employed in this study. The pilot MBR was fed with real municipal wastewater and the filtration flux, backwashing interval, aeration frequency and temperature were varied. A filtration flux below 25 I/m2h is generally recommended, at below this flux, the MBR operated at sub-critical flux conditions, the filter cake was minimized and membrane fouling was mainly attributed to the membrane pore blocking. Moreover, the membrane fouling, at below 25 I/m2h, was more reversible to backwashing; above this value, backwashing became less efficient to clean the membrane. Less frequent backwashing (e.g. 600 s filtration/45 s backwashing) decreased the amount of fouling irreversible to backwashing and its performance was superior to that of frequent backwashing (e.g. 200 s filtration/15 s backwashing). The MBR suffered more fouling at low temperature conditions (e.g. at 13-14 degrees C) than at high temperature conditions (e.g. at 17-18 degrees C). A conceptual model was built up and successfully interpreted this temperature effect.

Optimising the operation of a MBR pilot plant by quantitative analysis of the membrane fouling mechanism

Simultaneous wastewater treatment and lipid production by oleaginous microalgae show great potential to alleviate energy shortage and environmental pollution, because they exhibit tremendous advantages over traditional activated sludge. Currently, most research on wastewater treatment by microalgal are carried out at optimized temperature conditions (25–35 °C), but no information about simultaneous wastewater treatment and lipid production by microalgae at low temperatures has been reported. Microalgal growth and metabolism will be inhibited at low temperature conditions, and satisfactory wastewater treatment performance will be not obtained. Therefore, it is critical to domesticate and screen superior microalgal strains with low temperature adaptability, which is of great importance for wastewater treatment and biodiesel production. In this work, simultaneous wastewater treatment and lipid production were achieved by a microalgal mutant Scenedesmus sp. Z-4 at the low temperature conditions (4, 10, and 15 °C). The results showed that algal growth was inhibited at 4, 10, and 15 °C compared to that at the optimal temperature of 25 °C. However, decreased temperature had no significant effect on the total cellular lipid content of algae. Importantly, lipid productivity at 10 °C was compromised by more net energy output relevant to biodiesel production, which demonstrated that the low temperature of 10 °C was favorable to wastewater treatment and energy recovery by Scenedesmus sp. Z-4. When molasses wastewater with optimal COD concentration of 8000 mg L−1, initial inoculation ratio of 15%, and C/N ratio of 15 was used to cultivate microalgae, the maximum removal rate of COD, TN, and TP at 10 °C reached 87.2, 90.5, and 88.6%, respectively. In addition, lipid content of 28.9% and lipid productivity of 94.4 mg L−1 day−1 were obtained. Scenedesmus sp. Z-4 had good adaptability to low temperature conditions, and showed great potential to realize simultaneous wastewater treatment and lipid production at low temperatures. The proposed approach in the study was simple compared to other wastewater treatment methods, and this potential novel process was still efficient to remove COD, N, and P at low temperatures. Thus, it had a vital significance for the wastewater treatment in low temperature regions.

/pdf/molasses-wastewater-treatment-and-lipid-production-at-low-3cw1fhaqcg.pdf

Molasses wastewater treatment and lipid production at low temperature conditions by a microalgal mutant Scenedesmus sp. Z-4.

Effects of molecular weight distribution of soluble microbial products (SMPs) on membrane fouling in a membrane bioreactor (MBR): Novel mechanistic insights.

Membrane fouling is one of the most important considerations in the design and operation of membrane systems as it affects pretreatment needs, cleaning requirements, operating conditions, cost and performance. Given that membrane fouling represents the main limitation to membrane process operation, it is unsurprising that the majority of membrane material and process research and development conducted is dedicated to its characterization and amelioration. This work presents the fundamentals of fouling issues in membrane separations, with specific regard to membrane fouling in Membrane Bioreactors (MBRs) and the most frequently applied preventive-control strategies. Feed pretreatment, physical and chemical cleaning protocols, optimal operation of MBR process and membrane surface modification are presented and discussed in detail. Membrane fouling is the major obstacle to the widespread application of the MBR technology and, therefore, fouling preventive-control strategies is a hot issue that strongly concerns not only the scientific community, but industry as well.

Fouling Issues in Membrane Bioreactors (MBRs) for Wastewater Treatment: Major Mechanisms, Prevention and Control Strategies

Evaluation of a novel quorum quenching strain for MBR biofouling mitigation.

Mechanism of SMP aggregation within the pores of hydrophilic and hydrophobic MBR membranes and aggregates detachment

An innovative bioreactor set-up that reduces membrane fouling by adjusting the filamentous bacterial population

Membrane bioreactor (MBR) systems are connected to several advantages compared to the conventional activated sludge (CAS) units. This work aims to the examination of the life cycle environmental impact of an MBR against a CAS unit when treating municipal wastewater with similar influent loading (BOD = 400 mg/L) and giving similar high-quality effluent (BOD < 5 mg/L). The MBR unit contained a denitrification, an aeration and a membrane tank, whereas the CAS unit included an equalization, a denitrification, a nitrification, a sedimentation, a mixing, a flocculation tank and a drum filter. Several impact categories factors were calculated by implementing the Life Cycle Assessment (LCA) methodology, including acidification potential, eutrophication potential, global warming potential (GWP), ozone depletion potential and photochemical ozone creation potential of the plants throughout their life cycle. Real data from two wastewater treatment plants were used. The research focused on two parameters which constitute the main differences between the two treatment plants: The excess sludge removal life cycle contribution-where GWPMBR = 0.50 kg CO2-eq*FU-1 and GWPCAS = 2.67 kg CO2-eq*FU-1 without sludge removal-and the wastewater treatment plant life cycle contribution-where GWPMBR = 0.002 kg CO2-eq*FU-1 and GWPCAS = 0.14 kg CO2-eq*FU-1 without land area contribution. Finally, in all the examined cases the environmental superiority of the MBR process was found.

https://www.mdpi.com/2077-0375/10/12/421/pdf

Dimitra C. Banti

Papers

Fouling Issues in Membrane Bioreactors (MBRs) for Wastewater Treatment: Major Mechanisms, Prevention and Control Strategies

Evaluation of a novel quorum quenching strain for MBR biofouling mitigation.

Mechanism of SMP aggregation within the pores of hydrophilic and hydrophobic MBR membranes and aggregates detachment

An innovative bioreactor set-up that reduces membrane fouling by adjusting the filamentous bacterial population

LCA of a Membrane Bioreactor Compared to Activated Sludge System for Municipal Wastewater Treatment.