Modelling Biogas Fermentation from Anaerobic Digestion: Potato Starch Processing Wastewater Treated Within an Up flow Anaerobic Sludge Blanket

Abstract

IntroductionPotato is one of the most valuable food crop grown in many countries [1]. It has been reported that, a considerable proportion of the potato cultivated globally consumed through starch processing which subsequently generates tons of wastewater that goes to pollute water bodies [1][2][3]. Wastewater of raw potato processed into starch are classified as complex wastewater [4,5], and its concentration of chemical oxygen demand (COD), total suspended solid (TSS) and volatile suspended solid of (VSS) can yield concentrations of 50000, 9700 and 9500 mg/L, respectively [6]. Arhoun et al. argued that recovering valuable resource such as bioenergy (biogas) from such wastewater to supplement energy needs will be beneficial to humans and society at large [6,7]. Anaerobic digestion has severally been reported as a successful bioprocess treating various organic wastewaters and subsequently generating biogas [7][8][9][10][11][12]. However, the biological mechanism of anaerobic digestion is not well understood due to the complexity of the bacterial community structure and bioconversion [13]. Hu et al. asserted that process modeling is a good tool for predicting and describing the performance of biological processes [13]. Other reports also confirmed that process modeling based on previously acquired data is one technical route to enhancing the performance of anaerobic processes. These process models are often developed [14,15]. Nonetheless, modeling of anaerobic digestion is quite challenging and tough because performance of anaerobic systems is complex and varies considerably with influent characteristics and operational conditions [16].Some predictive models have been developed in the past decades for biogas estimation during anaerobic treatment processes. For instance, a regression analysis model for estimating biogas generated in a landfill leachate treatment process was developed by Akaya et al. AbstractHerein, a modeling approach to predict biogas yield within a mesophilic (35 ± 1°C) upflow anaerobic sludge blanket (UASB) reactor treating potato starch processing wastewater (PSPW) for pollutant removal was conducted. HRTs and seven anaerobic process-related parameters viz; chemical oxygen demand (COD), ammonium (NH 4 + ), alkalinity, total Kjeldahl Nitrogen, total phosphorus, volatile fatty acids (VFAs) and pH with average concentration of 4028.91, 110.09, 4944.67, 510.47, 45.20, 534.44 mg/L and 7.09, respectively, were used as input variables (x) to develop stochastic models for predicting biogas yield from the anaerobic digestion of PSPW. Based on the prediction accuracy of the models, it was established that, prediction of biogas yield from the UASB with the combination of COD, NH 4 + and HRT, or COD, NH 4 + , HRT and VFAs as input variables proved more efficient as opposed to HRT, alkalinity, total Kjeldahl Nitrogen, total phosphorus and pH. Highest coefficient of determination (R 2 ) observed was 97.29%, suggesting the efficiency of the models in making predictions. The developed models efficiencies co...

Synchytrium endobioticum – risk from biogas plants?

“…On average, residual waste of 33% is generated per kilogram of processed potatoes (IRENA, 2014). In Germany, 3.5 million tonnes of potatoes were processed in /2015(LfL, 2016, resulting in 1.1 million tonnes of potato waste and a large volume of process and wastewater (Li et al, 2015;Antwi et al, 2017). In Germany, 3.5 million tonnes of potatoes were processed in /2015(LfL, 2016, resulting in 1.1 million tonnes of potato waste and a large volume of process and wastewater (Li et al, 2015;Antwi et al, 2017).…”

“…Sepelev & Galoburda (2015) note that potatoes are usually peeled, with the amount of peel waste varying from 15% to 40% depending on the peeling method. In Germany, 3.5 million tonnes of potatoes were processed in /2015(LfL, 2016, resulting in 1.1 million tonnes of potato waste and a large volume of process and wastewater (Li et al, 2015;Antwi et al, 2017). Recycling or further processing would need to meet the demands of sustainability and avoid pollution.…”

“…Different options for further processing of potato wastes have been described in the literature, for example fermentation of potato peelings to lactic acid (Dreschke et al, 2015;Liang & McDonald, 2015), extraction of phenolic acid or steroidal alkaloids from potato peels (Wu, 2016), use of potato pulp as an additive for producing solid fuel pellets (Obidzi nski, 2014), fermentation of potato starch waste for the production of animal feed (Li et al, 2015) or the production of bioethanol and manure from potato waste (Khawla et al, 2014). However, the production by anaerobic digestion of methane-rich biogas for fuel seems to be the most common method of processing potato waste (Liang & McDonald, 2015;Jacob & Banjeree, 2016;Wu, 2016;Antwi et al, 2017). As potatoes can be infested by a large number of pathogens and other pests, the phytosanitary risks of digestates from biogas plants have to be assessed prior to returning them as fertilizer on arable land.…”

Aerobic and Anaerobic Sewage Biodegradable Processes: The Gap Analysis

“…UASB reactor is a high rate anaerobic system that widely used in tropical countries which the sewage temperature is about 24 0 C to 27 0 C [4]. As reported in many studies, this system was successfully removed high COD from wastewater in warm climate countries [14,18,19].It consists of thesimple solid-liquid-gas separator (GSL separator); the most important part of the system at upflow velocities of 1 to 2 meter per hour (figure 3). The separator connects the well-mixed feature of reactor contact system to separate the gas, liquid and solid phases through mechanisms of an internal gas separation and clarification.…”

“…The sludge increment also reduced COD removal rate that deteriorated the sludge stability [21,22]. Several alternatives were suggested to improve the degradation of suspended solids.This has led to the development of a novel technology such as two-stage anaerobic processes and chemically assisted sedimentation that consists of an integrated high loaded UASB reactor and a digester [18,19,23]. UASB-anaerobic digester is able to stabilize the entrapped sludge in the sludge bed, followed by improvement of its methanogenic capacity [21,24].…”