Biomass To Water Ratio Research Articles

Hydrothermal carbonization of organic waste using faecal sludge as a water source: Response surface methodology-Box Behnken design

In this research, organic waste was subjected to hydrothermal carbonization (HTC) using faecal sludge as the water source. HTC is a sustainable method for converting organic waste into valuable hydrochar. However, the use of portable water as a reaction medium in HTC is environmentally unsustainable and increases operational costs. The aim of this study was to optimize HTC operating parameters such as residence time, temperature, and biomass to water (BTW) ratio for maximizing both higher heating value (HHV) and hydrochar yield and also to determine the effects of these operating parameters on the hydrochar properties. This study utilized a Box Behnken design within the response surface methodology to identify optimal HTC conditions. Temperature was varied between 180 and 250 °C, residence time between 30 min and 120 min, and BTW ratio between 1 and 10. Volatile matter percentage was reduced in the hydrochar compared to that of the feedstock. A progressive rise in carbon percentage and a decline in oxygen percentage were observed with increasing temperatures. Temperature and residence time were the most significant factors affecting HHV, on the other hand, temperature and BTW ratio were the most significant factors that affected hydrochar yield. Numerical optimization of the factors revealed that a maximum HHV of 28.409 MJ/kg was obtained at 250 °C, 116 min, and a 1:9 BTW ratio, while an ideal hydrochar yield of 57.491% was obtained at 242 °C, 95 min and a BTW ratio of 1:9. This study highlights the environmental sustainability of utilizing faecal sludge as a water source in HTC, presenting a promising possibility for transforming organic waste into valuable hydrochar while addressing concerns related to water use.

High Dimensional Model Representation Approach for Prediction and Optimization of the Supercritical Water Gasification System Coupled with Photothermal Energy Storage

Supercritical water gasification (SCWG) coupled with solar energy systems is a new biomass gasification technology developed in recent decades. However, conventional solar-powered biomass gasification technology has intermittent operation issues and involves multi-variable characteristics, strong coupling, and nonlinearity. To solve the above problems, firstly, a solar-driven biomass supercritical water gasification technology combined with a molten salt energy storage system is proposed in this paper. This system effectively overcomes the intermittent problem of solar energy and provides a new method for the carbon-neutral process of hydrogen production. Secondly, the high dimensional model representation (HDMR) approach, as a surrogate model, was used to predict the production and lower heating value of syngas developed in Aspen Plus, which were validated using experimental data obtained from the literature. The ultimate analysis of biomass, temperature, pressure, and biomass-to-water ratio (BWR) were selected as input variables for the model. The non-dominated sorted genetic algorithm II (NSGA II) was considered to maximize the gasification yield of H2 and the LHV of syngas in the SCWG process for five different types of biomass. Firstly, the results showed that HDMR models demonstrated high performance in predicting the mole fraction of H2, CH4, CO, CO2, gasification yield of H2, and lower heating value (LHV) with R2 of 0.995, 0.996, 0.997, 0.996, 0.999, and 0.995, respectively. Secondly, temperature and BWR were found to have significant effects on SCWG compared to pressure. Finally, the multi-objective optimization results for five different types of biomass are discussed in this paper. Therefore, these operating parameters can provide an optimal solution for increasing the economics and characteristics of syngas, thus keeping the process energy efficient.

Production of hydrochar using pineapple (Ananas comosus) peelings via hydrothermal carbonization

The diminishing supply of fossil fuels as the primary energy source in the global context has prompted both researchers and scientists to look for sustainable alternative solid biofuel. One promising production approach is hydrothermal carbonization (H.T.C.) using biomass precursors. In this study, pineapple (Ananas comosus) waste peelings were utilized to obtain solid biofuel like hydrochar using H.T.C. at different carbonization times (C.T.), operating temperatures, and biomass-to-water ratio (BWR). The produced hydrochar was characterized using proximate analysis and higher heating value (HHV) and compared to the standard coal lignite. Results showed that the highest hydrochar yield of 39.33 % was obtained at 20% (BWR) for 5 hrs. (C.T.), while the lowest yield of 34% was obtained at 10% (B.W.) for 7 hrs. (C.T.). It was observed that the increase in hydrochar yield is associated with the increasing C.T. at lower BWR. In addition, the evaluated HHV was found to be 5805.01 cal/g and 5801.59 cal/g for 5 and 7 hrs. at 250 °C, respectively was obtained. Here the potential of pineapple-derived hydrochar as an option for biomass precursor for solid biofuels can help sustainably address the current scarcity of energy sources.

Biogas production from waste pulps of cassava (Manihot esculenta Crantz) via anaerobic digestion

The huge volume of wastes generated from industries kindles immediate attention, especially those wastes that bring adverse effects to humans and the environment. For one, cassava waste pulps (CWPs) from starch-producing industries are needing attention for its alternate disposal by making value-adding products out of it. In this work, the CWP with pig manure as inoculum was anaerobically digested for the possible production of biogas. The effect of the concentration of pig manure (CPM) and biomass to water ratio (BMR) was scientifically analyzed in relation to biogas yield. The central composite design of the response surface methodology was used as the design of the experiment. Biogas yield was modeled and characterized according to essential properties. The result of the batch experiment obtained a biogas yield of 4.9–7.3 L per kg of CWP. At optimized conditions of 250 gVS of CPM and 1:1.22 BWR (kg/L), the optimum biogas volume was 7.43 ± 0.58 L per kg of CWP. Analysis of the produced biogas via gas chromatography showed a significant concentration of biohydrogen (18.69 ± 1.71%), a highly desirable upshot considering that this gas is highly flammable with less emissions when combusted. Other percent components of the produced biogas include carbon dioxide (38.02 ± 0.71), nitrogen (20.77 ± 1.59), and a trace of methane (0.73 ± 0.28). This work, therefore, proved that CWP can be used for the production of biogas and would eventually provide practical solutions to starch processing industries as it gives promising lucrative routes of CWP with added commercial worth in the production of high-value energy resources like the desirable H2 gas. It poises high potentials with less socio-economic apprehensions while offers numerous environmental advantages.

Hydrothermal Carbonization of Biomass: Design of a Bench- Scale Reactor for Evaluating the Heat of Reaction

HydroThermal Carbonization (HTC) is a thermochemical process capable of converting wet biomass into a carbon-enriched solid, commonly referred to as hydrochar. Hydrochar finds application as bio-fuel, soil improver and for the production of carbon-advanced materials. In recent years, interest in HTC technology has grown significantly, in terms of both scientific research and industrial development. The HTC process consists of several reactions occurring both in series and in parallel: hydrolysis, dehydration, decarboxylation, condensation, aromatization, and others. Some reactions are known to be exothermic, while others are endothermic. Knowing the enthalpy of the “whole” HTC reaction would be beneficial in terms of both process design and energy calculations, in particular to evaluate the process heat duty. Unfortunately, such kind of information is barely available in the literature: some data have been obtained at the “micro-scale” using differential scanning calorimetry (DSC), with the limits of using a few milligrams of (usually heterogeneous) biomass per trial, while punctual data at larger scale are actually missing. In order to fill this gap, we designed and constructed in-house a 2 L batch reactor equipped with four thermocouples - placed at different heights inside the reactor - and capable to withstand pressures up to 140 bar and temperatures up to 300 °C. The reactor, controlled in temperature, is heated by four electrical resistances (1 kW each) and thermally insulated. An electric power meter allows monitoring and recording the electrical consumption during HTC trials.Thermal trials were performed with the bench-scale reactor fed with only water to provide a baseline for calculations. HTC trials were then performed using biomasses, namely organic fraction of municipal solid waste and agave pulp. At the different HTC operating conditions investigated (residence time: 3 h; reactor filling degree: 67 %; temperatures: 180, 220, and 250 °C; dry biomass to water ratio: 0.10 and 0.15), our data testify that the “whole” HTC reaction is exothermic, and the heat released by the reaction increases with temperature. The design of such a reactor and the data obtained so far encourage an in-depth analysis of the enthalpy of the HTC reaction for different biomasses and at various operating conditions.