Browsing by Author "Germain, Eve"

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    Ammonia removal from thermal hydrolysis dewatering liquors via three different deammonification technologies
    (Elsevier, 2020-10-06) Ochs, Pascal; Martin, Benjamin D.; Germain, Eve; Stephenson, Tom; van Loosdrecht, Mark C. M.; Soares, Ana
    The benefits of deammonification to remove nitrogen from sidestreams, i.e., sludge dewatering liquors, in municipal wastewater treatment plants are well accepted. The ammonia removal from dewatering liquors originated from thermal hydrolysis/anaerobic digestion (THP/AD) are deemed challenging. Many different commercial technologies have been applied to remove ammonia from sidestreams, varying in reactor design, biomass growth form and instrumentation and control strategy. Four technologies were tested (a deammonification suspended sludge sequencing batch reactor (S-SBR), a deammonification moving bed biofilm reactor (MEDIA), a deammonification granular sludge sequencing batch reactor (G-SBR), and a nitrification suspended sludge sequencing batch reactor (N-SBR)). All technologies relied on distinct control strategies that actuated on the feed flow leading to a range of different ammonia loading rates. Periods of poor performance were displayed by all technologies and related to imbalances in the chain of deammonification reactions subsequently effecting both load and removal. The S-SBR was most robust, not presenting these imbalances. The S-SBR and G-SBR presented the highest nitrogen removal rates (NRR) of 0.58 and 0.56 kg N m−3 d−1, respectively. The MEDIA and the N-SBR presented an NRR of 0.17 and 0.07 kg N m−3 d−1, respectively. This study demonstrated stable ammonia removal from THP/AD dewatering liquors and did not observe toxicity in the nitrogen removal technologies tested. It was identified that instrumentation and control strategy was the main contributor that enabled higher stability and NRR. Overall, this study provides support in selecting a suitable biological nitrogen removal technology for the treatment of sludge dewatering liquors from THP/AD
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    Biomass characteristics, aeration and oxygen transfer in membrane bioreactors: their interrelations explained by a review of aerobic biological processes
    (Springer, 2005-11) Germain, Eve; Stephenson, Tom
    Membrane bioreactor (MBR) is a promising alternative to conventional wastewater treatment methods. However this process is still under-used due to its high running costs. Its main power requirement comes from aeration, which is used to supply dissolved oxygen to the micro-organisms and to maintain the solids in suspension. In addition, in submerged MBRs, aeration is used for membrane cleaning. A complex matrix links the biomass characteristics, the aeration and the oxygen transfer. These parameters can impact on each other and/or delete one another effect. In order to understand the phenomena occurring in MBRs, similar aerobic biological processes, such as fermentation, mineral industry and slurry, were investigated. This review discusses the interrelations of the biomass characteristics (solids concentration, particle size and viscosity), the aeration intensity and the oxygen transfer in MBRs.
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    Biomass effects on oxygen transfer in membrane bioreactors.
    (Elsevier, 2007-03) Germain, Eve; Nelles, F.; Drews, A.; Pearce, P.; Kraume, M.; Reid, E.; Judd, Simon J.; Stephenson, Tom
    Ten biomass samples from both municipal and industrial pilot and full scale submerged membrane bioreactors (MBRs) with mixed liquor suspended solids concentrations (MLSS) ranging from 7.2 to 30.2 g L−1 were studied at six air-flow rates (0.7, 1.3, 2.3, 3, 4.4 and 6 m3 m−3 h−1). Statistical analyses were applied to identify the relative impacts of the various bulk biomass characteristics on oxygen transfer. Of the biomass characteristics studied, only solids concentration (correlated with viscosity), the carbohydrate fraction of the EPS (EPSc) and the chemical oxygen demand (COD) concentration of the SMP (SMPCOD) were found to affect the oxygen transfer parameters kLa20 (the oxygen transfer coefficient) and α-factor. The relative influence on kLa20 was MLSS>aeration>EPSc>SMPCOD and on α-factor was MLSS>SMPCOD>EPSc>aeration. Both kLa20 and α-factor increased with increasing aeration and EPSc and decreased with increasing MLSS and SMPCOD. MLSS was found to be the main parameter controlling the oxygen transfer.
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    Evaluation of a full-scale suspended sludge deammonification technology coupled with an hydrocyclone to treat thermal hydrolysis dewatering liquors
    (MDPI, 2021-02-01) Ochs, Pascal; Martin, Benjamin D.; Germain, Eve; Wu, Zhuoying; Lee, Po-Heng; Stephenson, Tom; van Loosdrecht, Mark C. M.; Soares, Ana
    Suspended sludge deammonification technologies are frequently applied for sidestream ammonia removal from dewatering liquors resulting from a thermal hydrolysis anaerobic digestion (THP/AD) process. This study aimed at optimizing the operation, evaluate the performance and stability of a full-scale suspended sludge continuous stirred tank reactor (S-CSTR) with a hydrocyclone for anaerobic ammonia oxidizing bacteria (AMX) biomass separation. The S-CSTR operated at a range of nitrogen loading rates of 0.08–0.39 kg N m−3 d−1 displaying nitrogen removal efficiencies of 75–89%. The hydrocyclone was responsible for retaining 56–83% of the AMX biomass and the washout of ammonia oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) was two times greater than AMX. The solid retention time (SRT) impacted on NOB washout, that ranged from 0.02–0.07 d−1. Additionally, it was demonstrated that an SRT of 11–13 d was adequate to wash-out NOB. Microbiome analysis revealed a higher AMX abundance (Candidatus scalindua) in the reactor through the action of the hydrocyclone. Overall, this study established the optimal operational envelope for deammonification from THP/AD dewatering liquors and the role of the hydrocyclone towards maintaining AMX in the S-CSTR and hence obtain process stability.
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    Micropollutant removal by advanced oxidation of microfiltered secondary effluent for water reuse
    (Elsevier Science B.V., Amsterdam., 2014-04-30T00:00:00Z) James, Christopher P.; Germain, Eve; Judd, Simon J.
    The removal of micropollutants (MPs) from secondary municipal wastewater by an advanced oxidation process (AOP) based on UV irradiation combined with hydrogen peroxide (UV/H2O2) has been assessed through pilot-scale experiments incorporating microfiltration (MF) and reverse osmosis (RO). Initial tests employed low concentrations of a range of key emerging contaminants of concern, subsequently focusing on the highly recalcitrant compound metaldehyde (MA), and the water quality varied by blending MF and RO permeate. Under optimum H2O2 and lamp power conditions, AOP achieved significant removal (>99%) of N-nitrosodimethylamine (NDMA) and endocrine disrupting compounds (EDCs) for all waters. Pesticide removal, in particular metaldehyde, atrazine and 2,4,5-trichlorophenoxyacetic acid, was dependent on water transmittance (UVT), and levels of TOC and other hydroxyl radical (OH) scavengers. Further analysis of MA removal showed UVT, hydraulic retention time and H2O2 dose to be influential parameters in determining degradation as a function of UV dose. A cost assessment revealed energy consumption to account for 65% of operating expenditure with lamp replacement contributing 25%. A comparison of three unit process sequences, based on MF, RO, AOP and activated carbon (AC), revealed MF-RO-AOP to be the most cost effective provided management of the RO concentrate stream incurred no significant cost. Results demonstrated AOPs to satisfactorily reduce levels of the more challenging recalcitrant MPs to meet stringent water quality standards for wastewater reuse, but that practical limitations exist and the cost penalty is significant.
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    Raw and analysed data for four ammonia removal technologies treating THP/AD dewatering liquors
    (Cranfield University, 2020-10-09 09:06) Ochs, Pascal; Soares, Ana; Stephenson, Tom; D. Martin, Benjamin; Germain, Eve; van Loosdrecht, M.C.M. (Mark)
    The data set contains influent, effluent and performance data for the paper "Ammonia removal from thermal hydrolysis dewatering liquors via three different deammonification technologies". The data is stored in an excel spreadsheet including raw data, cleaned up data and details to analysis.