Boltz, Joshua

Joshua is a Woodard & Curran Vice President and Principal, Professional Engineer, Board Certified Envrionmental Engineer, and IWA Fellow. His work focuses on biofilm reactors and mathematical modeling.

Titles from this speaker

Evaluating Nitrogen Oxides Transformations at Low Dissolved Oxygen Concentrations

Abstract

This paper was presented at WEFTEC 2023 in Chicago, IL.

This study evaluates nitrogen oxides transformations at low-DO concentrations. Microbial community data coupled with biokinetics, and detailed process modeling facilitated an analysis of the fundamental mechanisms associated with SND and its interaction between biomass and intermediate nitrogen oxide species and readily biodegradable COD.

SpeakerJimenez, Jose

Presentation time

08:30:00

08:50:00

Session time

08:30:00

10:00:00

SessionLow Carbon BNR Fundamentals and Controls

Session locationRoom S502 - Level 5

TopicAdvanced Level, Facility Operations and Maintenance, Municipal Wastewater Treatment Design, Nutrients

Author(s)

Jimenez, Jose

Author(s)J. Jimenez 1; J. Boltz 2 ; M. Miller 3; K. Bauhs 5; B. Sturm 6; B. Rittmann 7; J. Jimenez 1;

Author affiliation(s)Brown and Caldwell 1; Woodard and Curran 2 ; Brown and Caldwell 3; Brown and Caldwell 5; University of Kansas 6; Arizona State University 7; Brown and Caldwell 1;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159062

Volume / Issue

Content sourceWEFTEC

Word count10

Improving Clarifier Models by Describing Extracellular Polymeric Substances

Abstract

Improved settleability in activated sludge processes is an essential feature of new innovations. To accelerate the adoption of such technologies, the ability to link operational conditions with settling characteristics is needed to support process design and prediction of improvements in settleability. The previous works indicated that the threshold of flocculation (TOF) (Mancell-Egala et al., 2017a), which describes the collision efficiency of particles, was successfully introduced as a simple experimental method to calculate the flocculent settling coefficient (rp) in 1-D clarifier models and to enhance the ability to predict clarifier effluent solids. TOF also showed to have a clear relationship with effluent quality making it a useful operational parameter to detect flocculation limitations. In addition, extracellular polymeric substances (EPS) quality, most often expressed as a protein over polysaccharides ratio has been linked to flocculation behavior, densification and granulation (McSwain et al., 2005). This knowledge was used to develop an empirical function between the composition of (EPS) expressed as EPS-TKN/COD and TOF. This relationship between EPS composition and TOF was introduced as a means of linking biological process models (i.e. Sumo2C model) and 1-D clarifier models (Ngo et al., 2021b). Essential for this approach is the prediction of EPS amounts and quality from process models as a function of feast-famine, and other operational conditions as this defines settling behavior. This paper discusses three approaches for EPS prediction from process models and will provide insights on 2 which type of EPS modeling might be needed for different purposes. While this abstract describes different datasets tested for the different models, the full paper will provide a full comparison of the three models on the full-scale dataset collected at Blue Plains

This paper discusses three approaches for EPS prediction from process models and will provide insights on which type of EPS modeling might be needed for different purposes. With optimized EPS quality prediction, it is possible to simulate settling improvements based on changes in operational conditions both based on a wide range of SRT as well as based on feast-famine driver. The latter will help to accelerate the adoption of intensification technologies.

SpeakerNgo, Nam

Presentation time

10:35:00

10:50:00

Session time

10:30:00

12:00:00

SessionPushing the Boundaries of Our Biological Models

Session locationRoom S404a - Level 4

TopicFacility Operations and Maintenance, Intermediate Level, Municipal Wastewater Treatment Design, Research and Innovation

Author(s)

Ngo, Khoa Nam

Author(s)N. Khoa Nam 1; T. Wadhawan 2 ; B. Sturm 3; J.P. Boltz 4; J. Hinojosa 5; A.N. Massoudieh 6; I. Takacs 7; J. Jimenez 8; H. De Clippeleir 9;

Author affiliation(s)District of Columbia Water and Sewer Authority 1; Dynamita SARL, France 2 ; University of Kansas 3; Woodard & Curran Arizona State University, USA 4; District of Columbia Water and Sewer Authority 5; Catholic University of America 6; Dynamita SARL, France 7; Brown and Caldwell, USA 8; District of Columbia Water and Sewer Authority, USA 9;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159190

Volume / Issue

Content sourceWEFTEC

Word count9

Mathematical Modeling of an Anaerobic Moving Bed Biofilm Reactor

Abstract

Introduction Biofilm accumulation on plastic carriers in an Anaerobic Moving Bed Biofilm Reactor (AnMBBR) depends on the (1) surface loading of biodegradable organics (g COD/m2-d), (2) time for the syntheses of microorganisms and biofilm accumulation, and (3) net rate of biofilm attachment/detachment. We developed and used mathematical models of an AnMBBR, 1-D biofilm, and biochemical transformations by bacteria, archaea, and enzymes. Objectives were to simulate experimental scenarios and describe total chemical oxygen demand (TCOD) removal, methane (CH4) generation, and biofilm structure and function. Materials and Methods Physical System: di Biase et al. (2018) investigated the effects of increasing TCOD volumetric loading rate (VLR) on its removal and CH4 production in three 4-L AnMBBRs treating brewery wastewater. Each AnMBBR had a 40% volumetric fill of ActiveCellTM 920 plastic carriers, which has a reported 680-m2/m3 specific surface area (SSA). The TCOD VLR was increased from 3.9 to 19.5 kg CODT/m3-d, and each loading condition lasted for 25 days. Process Model: A process model of biological and enzymatic processes included eight soluble and eight particulate state variables. Heterotrophic bacteria (XF) and acetate-cleaving methanogenic archaea (XM) syntheses and endogenous decays were modeled. Heterotrophic bacteria fermented readily biodegradable COD (SB) into volatile fatty acids (SVFA). Methanogenic archaea fermented SVFA into dissolved CH4 (SCH4) and carbon dioxide. Substrate transformations led to synthesis of active biomass, utilization associated products (SUAP), protein-extracellular polymeric substance (XEPS,P), carbohydrate-extracellular polymeric substances (XEPS,C), and hydrolytic enzymes (XHYD). Endogenous-decay products included XEPS,P, XEPS,C, biodegradable endogenous decay products (XEDP), and unbiodegradable endogenous decay products (XEDP,U). Extracellular enzymes catalyzed the hydrolysis of slowly biodegradable COD (XB), XEDP, XEPS,P, and XEPS,C. Protein-EPS and XEDP were hydrolyzed into protein-biomass associated products (SBAP,P), XEPS,C hydrolyzed into carbohydrate-biomass associated products (SBAP,C), and XB hydrolyzed into SB. Biofilm Model: A numerical, 1-D biofilm model following Wanner et al. (2006) and protocols from the Good Biofilm Reactor Modeling Practice (Rittmann et al. 2018) were applied. The modeled biofilm had a thickness (LF) that was discretized as 10 layers. Biofilms were modeled on the protected interior surfaces of plastic carriers, and biofilm area (AF) was modeled to decrease as LF increases, as illustrated by Figure 1. A mass-transfer boundary layer (MTBL) with variable thickness (LL) modeled mass-transfer resistance external to the biofilm. The transformation of soluble substrate i inside the biofilm was modeled as simultaneous diffusion and reaction. The ratio of DF,i to DW,i was set to 0.80. The rate of particle attachment to the biofilm surface was modelled as the product of the total suspended solids (TSS) concentration in the water (XTSS) and an attachment rate coefficient (katt). The rate of total solids (TS) detachment from the biofilm surface was modeled with a second-order expression that multiplied a detachment rate coefficient (kdet) by LF^2. LF, katt, and kdet were adjusted to maintain a TS concentration less than 300,000 g CODX/m3 inside each biofilm layer. Bioreactor Model and Simulator: The laboratory AnMBBR was modeled as a continuous flow stirred tank reactor. Water displacement by plastic carriers was included. The WWTP simulator SUMO (Dynamita, France) was utilized. Results and Discussion Simulations matched the experimental results of di Biase et al. (2018), see Figure 2. Most of the effluent COD was soluble COD (SCOD) that consisted of SB, SVFA, SUAP, SBAP,P, and SBAP,C, see Figure 3. Most of the SCOD was SVFA. Furthermore, the sum of COD in the effluent, including SCH4, was less than the influent TCOD. Thus, 25 days was not long enough to establish a steady-state LF. Although increasing the TCOD VLR led to increased COD removal rates and conversion to CH4 (expressed in kg COD/m3-d), the fractional conversions declined. The CH4-production rate increased from 0.012 to 0.043 kg COD/d from the first to the sixth stage, but the fractional COD conversion to CH4 dropped from 85 to 59%. The modeled LF increased with TCOD VLR, but the biofilm SSA decreased as the carrier channels filled with biofilm, see Figure 4. This AF loss was an important reason why TCOD removal and CH4 production rates did not increase linearly with the increasing TCOD VLR. Figure 5, which includes 1-D profiles of solids concentrations inside the biofilm, indicates that increasing TCOD VLR led to increased accumulation of endogenous-decay products and methanogenic archaea near the substratum, while the outer portion of the biofilm was enriched in fermenting heterotrophic bacteria. Methanogenic archaea accumulation near the substratum contributed to the relative slowdown of CH4 production for high TCOD VLR. Conclusions Integrated models described measured results from the experimental study by di Biase et al. (2018). Increasing the TCOD VLR led to lower ratios of COD removal and its conversion to CH4. Although higher TCOD VLR led to greater LF, it also was associated with lower SSA and increased accumulation of endogenous-decay products and methanogens deep in the biofilm, which contributed to less conversion of TCOD to CH4.

Sub-models of transformation processes by microorganisms and hydrolytic enzymes, a 1-D biofilm, and a bioreactor were integrated to simulate organic-matter fermentation and CH4 production in a laboratory-scale AnMBBR. The integrated models correctly represented all experimental observations and identified mechanisms underlying how and why the AnMBBR's performance changed when the volumetric loading rate (VLR) of TCOD increased from 3.9 to 19.5 kg CODT/m3-d.

SpeakerBoltz, Joshua

Presentation time

14:30:00

14:50:00

Session time

13:30:00

15:00:00

SessionMechanistic Modeling Developments for Newer Processes

Session number410

Session locationRoom 244

TopicAdvanced Level, Biosolids and Residuals, Industrial Issues and Treatment Technologies, Municipal Wastewater Treatment Design, Research and Innovation

Author(s)

Boltz, Joshua, Rittmann, Bruce, Cai, Yuhang

Author(s)J.P. Boltz1, B.E. Rittmann2, Y. Cai3

Author affiliation(s)1Woodard & Curran, AL, 2Arizona State University, AZ, 3Arizona State University

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159531

Volume / Issue

Content sourceWEFTEC

Word count10

Description: Mobile Biofilms for Biological Nutrient Removal and Wastewater Treatment Process...

Mobile Biofilms for Biological Nutrient Removal and Wastewater Treatment Process Intensification

Abstract

The Mobile-Organic Biofilm (MOB) process includes mobile biofilms and their retention screens with a bioreactor and liquid and solids separation. The MOB process is inexpensive, easy-tointegrate with wastewater treatment (WWT) processes, and provides for high-rate WWT in biofilm or hybrid bioreactors. This paper describes mathematical modeling of the MOB process presented by Boltz and Daigger (2022). This paper describes MOB process (1) modes of operation, (2) design and analysis methodology, and (3) mathematical modeling. The mathematical model was applied to simulate a fixed bioreactor volume and secondary-clarifier area as MOB process Modes I, II, and III. Simulated differences between MOB process modes of operation are described.

This paper was presented at WEFTEC 2023 in Chicago, IL.

SpeakerBoltz, Joshua

Presentation time

11:15:00

11:30:00

Session time

10:30:00

12:00:00

SessionPushing the Boundaries of Our Biological Models

Session locationRoom S404a - Level 4

TopicFacility Operations and Maintenance, Intermediate Level, Municipal Wastewater Treatment Design, Research and Innovation

Author(s)