Data-driven Soft Sensors in the Process Industry

In the last two decades Soft Sensors established themselves as a valuable alternative to the traditional means for the acquisition of critical process variables, process monitoring and other tasks which are related to process control. This paper discusses characteristics of the process industry data which are critical for the development of data-driven Soft Sensors. These characteristics are common to a large number of process industry fields, like the chemical industry, bioprocess industry, steel industry, etc. The focus of this work is put on the data-driven Soft Sensors because of their growing popularity, already demonstrated usefulness and huge, though yet not completely realised, potential. A comprehensive selection of case studies covering the three most important Soft Sensor application fields, a general introduction to the most popular Soft Sensor modelling techniques as well as a discussion of some open issues in the Soft Sensor development and maintenance and their possible solutions are the main contributions of this work

Comparison of ν-support vector regression and logistic equation for descriptive modeling of Lactobacillus plantarum growth

Due to the complexity and high non-linearity of bioprocess, most simple mathematical models fail to describe the exact behavior of biochemistry systems. As a novel type of learning method, support vector regression (SVR) owns the powerful capability to characterize problems via small sample, nonlinearity, high dimension and local minima. In this paper, we developed a ν-SVR model with genetic algorithms (GA) in the pre-estimate in Lactobacillus plantarum fermentation by comparing the predicting capability of logistic model and SVR model. 5-fold cross validation technique was applied in the SVR train to avoid over-fitting. The information of SVR parameters were obtained in the generation of 150 and the optimal parameters were C= 235.8935, σ= 8.3608, ν=0.7587. Correspondingly, the logistic model parameters μmax and xmax were estimated as 0.4791 and 0.3498, respectively. The experimental results demonstrated that, SVR model excelled the logistic model based on the normalized mean square error (NMSE), mean absolute percentage error (MAPE) and the Pearson correlation coefficient R. We found that the ν-SVR model optimized by genetic algorithms could be a potential monitoring method for prediction of biomass.Key words: Support vector regression, genetic algorithm, logistic model, prediction of biomass

Data-driven soft-sensors for online monitoring of batch processes with different initial conditions

A soft-sensing methodology applicable to batch processes operated under changeable initial conditions is presented. These cases appear when the raw materials specifications differ from batch to batch, different production scenarios should be managed, etc. The proposal exploits the capabilities of the machine learning techniques to provide practical soft-sensing approach with minimum tuning effort in spite of the fact that the inherent dynamic behavior of batch systems are tracked through other online indirect measurements. Current data modeling techniques have been also tested within the proposed methodology to demonstrate its advantages. Two simulation case-studies and a pilot-plant case-study involving a complex batch process for wastewater treatment are used to illustrate the problem, to assess the modeling approach and to compare the modeling techniques. The results reflect a promising accuracy even when the training information is scarce, allowing significant reductions in the cost associated to batch processes monitoring and control.Peer ReviewedPostprint (author's final draft

Machine learning in bioprocess development: From promise to practice

Fostered by novel analytical techniques, digitalization and automation, modern bioprocess development provides high amounts of heterogeneous experimental data, containing valuable process information. In this context, data-driven methods like machine learning (ML) approaches have a high potential to rationally explore large design spaces while exploiting experimental facilities most efficiently. The aim of this review is to demonstrate how ML methods have been applied so far in bioprocess development, especially in strain engineering and selection, bioprocess optimization, scale-up, monitoring and control of bioprocesses. For each topic, we will highlight successful application cases, current challenges and point out domains that can potentially benefit from technology transfer and further progress in the field of ML

The effect of reactor configuration on bioelectrochemical production of acetate from carbon dioxide

To mitigate global warming and its adverse effects, more sustainable alternatives for the fossil fuel-based production of energy and chemicals are needed. Acetogenic bacteria can reduce the greenhouse gas CO2 into hydrocarbons like acetate using reducing equivalents supplied via a cathode in a bioelectrochemical system. However, the production process needs improvements to enable cost-effective production in an industrial scale. To improve the process, a fluidized bed reactor (FluBR) was tested to enhance mass transfer. The tubular cathode chamber inside the cylindrical anode chamber hosted a mixed culture of acetogens and activated carbon granules, which were fluidized at a flow rate of 170 mL/min. As a control for fluidization, a fixed bed reactor (FixBR) was prepared by replacing the bed material with heavier graphite granules, while the flow rate was 250 mL/min. Both reactors supported bioelectrochemical production of acetate reaching their peak performance 14 days after the acetate production had started. The maximum volumetric productivity was 0.21 g/L/d in the FluBR and 0.22 g/L/d in the FixBR while 37 % and 40 % of the electrons provided by the cathode were assimilated into acetate in the FluBR and the FixBR, respectively. The performance of the FixBR and the FluBR were similar, but the differences between the reactor setups could have affected the results. The reactors need to be further tested for comparable results and optimized to improve the acetate production.Ilmastonmuutoksen ja sen haittavaikutuksien vähentämiseksi tarvitaan kestävämpiä vaihtoehtoja fossiilisille polttoaineille ja kemikaaleille. Mikrobielektrosynteesissä asetogeeniset bakteerit käyttävät katodilta saatuja elektroneja hiilidioksidin pelkistämiseen muodostaen hiilivetyjä kuten asetaattia. Jotta menetelmää voitaisiin käyttää kustannustehokkaasti teollisessa mittakaavassa, tuottoprosessia pitäisi parantaa. Työn tarkoitus oli parantaa mikrobielektrosynteesin tehokkuutta parantamalla massansiirtoa leijupetireaktorin avulla. Reaktorin sylinterimäisen anodikammion sisällä oli putkimainen katodikammio, jossa kasvatettiin asetogeeneja sisältävää sekaviljelmää. Katodikammioon lisättiin aktiivihiilirakeita, joita leijutettiin 170 ml/min virtausnopeudella. Leijupetireaktorin kontrollina käytettiin muuten samanlaista kiintopatjareaktoria, jossa aktiivihiilirakeiden sijaan käytettiin raskaampia grafiittirakeita, joiden läpi kasvatusmediumia kierrätettiin 250 ml/min virtausnopeudella. Molemmat reaktorit tukivat asetaatin biosähkökemiallista muodostusta saavuttaen suurimmat tuottonsa ja tehokkuutensa 14 päivää asetaatin tuoton alkamisen jälkeen. Suurin volumetrinen tuottavuus oli 0.21 g/L/d leijupetireaktorissa ja 0.22 g/L/d kiintopatjareaktorissa. Lisäksi leijupetireaktorissa enimmillään 37 % ja kiintopatjareaktorissa enimmillään 40 % katodilta saaduista elektroneista hyödynnettiin asetaatin tuottoon. Reaktorien tulokset olivat lähes samanlaiset, mutta reaktorien väliset erot esimerkiksi virtausnopeudessa ovat voineet vaikuttaa tuloksiin. Reaktoreita tulisi siis tutkia ja kehittää edelleen vertailukelpoisempien tulosten sekä parempien tehokkuuksien ja tuottavuuksien saavuttamiseksi

Revelation of Yin-Yang Balance in Microbial Cell Factories by Data Mining, Flux Modeling, and Metabolic Engineering

The long-held assumption of never-ending rapid growth in biotechnology and especially in synthetic biology has been recently questioned, due to lack of substantial return of investment. One of the main reasons for failures in synthetic biology and metabolic engineering is the metabolic burdens that result in resource losses. Metabolic burden is defined as the portion of a host cells resources either energy molecules (e.g., NADH, NADPH and ATP) or carbon building blocks (e.g., amino acids) that is used to maintain the engineered components (e.g., pathways). As a result, the effectiveness of synthetic biology tools heavily dependents on cell capability to carry on the metabolic burden. Although genetic modifications can effectively engineer cells and redirect carbon fluxes toward diverse products, insufficient cell ATP powerhouse is limited to support diverse microbial activities including product synthesis. Here, I employ an ancient Chinese philosophy (Yin-Yang) to describe two contrary forces that are interconnected and interdependent, where Yin represents energy metabolism in the form of ATP, and Yang represents carbon metabolism. To decipher Yin-Yang balance and its implication to microbial cell factories, this dissertation applied metabolic engineering, flux analysis, data mining tools to reveal cell physiological responses under different genetic and environmental conditions. Firstly, a combined approach of FBA and 13C-MFA was employed to investigate several engineered isobutanol-producing strains and examine their carbon and energy metabolism. The result indicated isobutanol overproduction strongly competed for biomass building blocks and thus the addition of nutrients (yeast extract) to support cell growth is essential for high yield of isobutanol. Based on the analysis of isobutanol production, \u27Yin-Yang\u27 theory has been proposed to illustrate the importance of carbon and energy balance in engineered strains. The effects of metabolic burden and respiration efficiency (P/O ratio) on biofuel product were determined by FBA simulation. The discovery of energy cliff explained failures in bioprocess scale-ups. The simulation also predicted that fatty acid production is more sensitive to P/O ratio change than alcohol production. Based on that prediction, fatty acid producing strains have been engineered with the insertion of Vitreoscilla hemoglobin (VHb), to overcome the intracellular energy limitation by improving its oxygen uptake and respiration efficiency. The result confirmed our hypothesis and different level of trade-off between the burden and the benefit from various introduced genetic components. On the other side, a series of computational tools have been developed to accelerate the application of fluxomics research. Microbesflux has been rebuilt, upgraded, and moved to a commercial server. A platform for fluxomics study as well as an open source 13C-MFA tool (WUFlux) has been developed. Further, a computational platform that integrates machine learning, logic programming, and constrained programming together has been developed. This platform gives fast predictions of microbial central metabolism with decent accuracy. Lastly, a framework has been built to integrate Big Data technology and text mining to interpret concepts and technology trends based on the literature survey. Case studies have been performed, and informative results have been obtained through this Big Data framework within five minutes. In summary, 13C-MFA and flux balance analysis are only tools to quantify cell energy and carbon metabolism (i.e., Yin-Yang Balance), leading to the rational design of robust high-producing microbial cell factories. Developing advanced computational tools will facilitate the application of fluxomics research and literature analysis

BacHBerry: BACterial Hosts for production of Bioactive phenolics from bERRY fruits

BACterial Hosts for production of Bioactive phenolics from bERRY fruits (BacHBerry) was a 3-year project funded by the Seventh Framework Programme (FP7) of the European Union that ran between November 2013 and October 2016. The overall aim of the project was to establish a sustainable and economically-feasible strategy for the production of novel high-value phenolic compounds isolated from berry fruits using bacterial platforms. The project aimed at covering all stages of the discovery and pre-commercialization process, including berry collection, screening and characterization of their bioactive components, identification and functional characterization of the corresponding biosynthetic pathways, and construction of Gram-positive bacterial cell factories producing phenolic compounds. Further activities included optimization of polyphenol extraction methods from bacterial cultures, scale-up of production by fermentation up to pilot scale, as well as societal and economic analyses of the processes. This review article summarizes some of the key findings obtained throughout the duration of the project

Knowledge discovery and data mining to understand and optimise the environmental behavior of wastewater treatment processes

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University LondonDirect nitrous oxide (N2O) emissions during the biological nitrogen removal (BNR) processes can significantly increase the carbon footprint of wastewater treatment plant (WWTP) operations. However, quantifying the emissions and understanding the long-term behaviour of N2O fluxes in WWTPs remains challenging and costly. The aim of the current research is to combine wastewater domain knowledge with data-mining techniques to explain the long-term N2O emissions’ behaviour in full-scale biological reactors. A review of the recent full-scale N2O monitoring campaigns is conducted resulting in the development of an emission factor (EF) database with information on configurations, control strategies and operational conditions. The analysis focused on mechanistic model development, molecular biology methods and on the current data management and analysis practices (i.e. visualization techniques, statistical analysis). Sensor and laboratory data acquired from the N2O monitoring campaigns of mainstream and sidestream wastewater processes were used to develop, test and validate a methodological framework for knowledge discovery in wastewater databases. Abnormal events detection, structural changepoint detection, clustering, classification and regression algorithms are used in order to i) translate data into actionable information, ii) link N2O emissions ranges with specific operational conditions, iii) identify and isolate re-occurring system disturbances that affect performance, iv) predict the range of N2O emissions based on operational and environmental conditions and v) provide feedback to monitoring campaigns for the minimisation of sampling requirements. The analysis showed that the relationship of N2O emissions with the operational variables fluctuates in long-term monitoring campaigns; this should be taken into consideration for the development of mitigation measures and during the investigation of triggering operational conditions. Additionally, findings indicate that structural changepoints of operational variables monitored online can be used to detect changes in the behaviour and range of N2O emissions. Finally, data-driven models can reliably estimate N2O behaviour in wastewater processes under given operational conditions. However, fluctuation of dependencies, system disturbances and process-specific characteristics should be taken into consideration

The role of artificial intelligence-driven soft sensors in advanced sustainable process industries: a critical review

With the predicted depletion of natural resources and alarming environmental issues, sustainable development has become a popular as well as a much-needed concept in modern process industries. Hence, manufacturers are quite keen on adopting novel process monitoring techniques to enhance product quality and process efficiency while minimizing possible adverse environmental impacts. Hardware sensors are employed in process industries to aid process monitoring and control, but they are associated with many limitations such as disturbances to the process flow, measurement delays, frequent need for maintenance, and high capital costs. As a result, soft sensors have become an attractive alternative for predicting quality-related parameters that are ‘hard-to-measure’ using hardware sensors. Due to their promising features over hardware counterparts, they have been employed across different process industries. This article attempts to explore the state-of-the-art artificial intelligence (Al)-driven soft sensors designed for process industries and their role in achieving the goal of sustainable development. First, a general introduction is given to soft sensors, their applications in different process industries, and their significance in achieving sustainable development goals. AI-based soft sensing algorithms are then introduced. Next, a discussion on how AI-driven soft sensors contribute toward different sustainable manufacturing strategies of process industries is provided. This is followed by a critical review of the most recent state-of-the-art AI-based soft sensors reported in the literature. Here, the use of powerful AI-based algorithms for addressing the limitations of traditional algorithms, that restrict the soft sensor performance is discussed. Finally, the challenges and limitations associated with the current soft sensor design, application, and maintenance aspects are discussed with possible future directions for designing more intelligent and smart soft sensing technologies to cater the future industrial needs