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Biogas, an alternative energy source derived from organic materials, particularly POME, is produced through anaerobic digestion. The utilization of an UASB-HCPB fermenter has successfully yielded biogas with elevated methane content. However, the produced biogas still contained a moderate amount of CO2, necessitating further purification to make the biogas suitable for engine fuel applications. The presence of CO2 must be mitigated through an absorption method. The amount of CO₂ removed from biogas required an absorption system designed to utilize environmentally friendly solvents that can operate effectively at low pressures. The absorption design is important in designing absorber columns, particularly packed column types. It requires careful consideration of flow rates and absorbent concentrations to ensure optimal performance and suitability for industrial applications. This study aims to elaborate the design, fabrication, and performance of a packed absorption column for CO2 removal utilizing K2CO3 as a solvent with MSG as a promoter. K2CO3 promoted with MSG represents an eco-friendly solvent with potential for biogas purification applications. The novelty of this study highlights a gap in integrating biogas production and purification design, wherein biogas generated from anaerobic digestion of POME undergoes purification via an absorption system. Experimental parameters included absorbent flow rates of 1, 1.5, and 2 L/min; a biogas flow rate of 20 L/min; promoter concentrations of 1, 3, and 5 %; temperatures of 35, 45, and 55 °C; and a contact time of 5 min. Results indicated that optimal CO2 removal (47.38±1.58 %) was achieved with an absorbent flow rate of 2 L/min and MSG concentration of 5 %. Based on the calibration results, the distilled water, air, and CO2 flowmeters have regression values (R²) of 0.9947, 1.0000, and 0.9253, respectively. The highest CO2 removal was 94.44 % on CO2 flow rate of 5 L/min, air flow rate of 20 L/min and absorbent flowrate of 1.8 L/min. Maximum CO2 loading (0.0081 mol CO2/mol K2CO3) was obtained at an absorbent flow rate of 1 L/min and MSG concentration of 5 %. Temperature effects revealed optimal CO2 removal (63.32±0.42 %) at 55 °C, while peak CO2 loading (0.00987 mol CO2/mol K2CO3) occurred at 45 °C. At 55 °C, the final biogas composition achieved was 94.18 % CH4, 5.81 % CO2, and 0.01 % H2S. These results indicate an increase in the effectiveness of CO2 removal and high-purity biogas products. However, future research of synergistic study is needed on the regeneration capability of monosodium glutamate-activated K2CO3 for long-term CO2 absorption. Futhermore, development of the absorption column design is also needed by considering the operating pressure. It is expected that this initial study on integrated biogas production and purification can be further developed and applied to the palm oil industry to support the implementation of sustainable zero waste technology.

The Institute of Engineering (IOE), Pulchowk Campus in Lalitpur, Nepal, faces serious solid waste mismanagement issues that threaten the environment and public health. In a comprehensive investigation from June 5 to 12 June 2022, IOE students sorted waste from 58 campus locations. They discovered that the average weights of plastic, paper, and organic waste were 5.84 kg, 8.85 kg, and 3.76 kg, respectively. The study identified current waste management risks and provided recycling strategies, emphasising the 3Rs (Reduce, Reuse, Recycle). Aspen Plus simulation indicated that 0.72 kg/day of segregated HDPE waste produced 0.65 kg/day of liquid fuel. The construction of a pyrolysis plant is estimated to cost NPR 27,11,528.794, with an annual operational expense of NPR 1,39,510. These findings highlight the necessity of proactive environmental management and offer suggestions for sustainable waste management in urban and educational settings.

The escalating environmental threat of heavy metal pollution particularly copper ions emphasizes the importance of wastewater treatment methods. A practical approach is adsorption using plant biomass. This study used column adsorption by comparing the downflow and upflow processes to remove cupric (Cu2+) ion from solution by adsorbent from rambutan stems charcoal that not activated and activated using nitric acid. The adsorbent size was 50 mesh, 70 mesh, and 100 mesh, the feed flow rates was 5 mL/min and 10 mL/min, initial concentrations of Cu2+ ion was 50 mg/L and 150 mg/L. The Cu2+ ion solution was pumped by upflow and downflow after the activated rambutan stem charcoal was inserted into the column. Fourier Transform Infra-Red carried out for analysis the functional group of the adsorbent before and after the activation. Changes in pore structure and chemical composition were verified by Scanning Electron Microscopy-Energy Dispersive X-Ray analysis. The modelling with breakthrough curve and modeling of Bohart-Adam model, Yoon-Nelson model and Thomas model are determined to fit the both column adsorption processes. Based on the results, the highest removal efficiency was 82.71 % obtained at Cu2+ ion concentration of 50 mg/L by upflow adsorption at flow rate of 5 mL/min using 100 mesh of activated charcoal of rambutan stem achieved of 2.87 min loading time. The result of this study describe the increase in removal efficiency occurred at lower Cu2+ ion concentrations with lower flow rate while using of larger adsorbent size. Longer loading times achieved at the increasing of Cu2+ ion concentration, decreasing of flow rate, and increasing of adsorbent size led to. Compared to downflow adsorption, upflow adsorption has a longer loading time. The breakthrough curve has ''S'' shaped profile for both upflow and downflow adsorption. However, the upflow adsorption breakthrough curve is more reliable as well as other modeling fittings showed higher coefficient of determination than the downflow.

The quality of cooking oil needs to be maintained. To purify used cooking oil, an adsorption process involving adsorbents is required. In this study, a 100 mL sample of used cooking oil was taken. The oil was then left to settle for 20 min before measuring the initial turbidity level with a turbidimeter. In manufacturing adsorbents from corncob powder with sizes 50 mesh, 70 mesh, and 100 mesh, each weighed as much as 25 g, mixed with 150 ml of 0.1 M hydrochloric acid for 3 h, and dried in the oven. Each size of adsorbent was weighed as much as 2 g, 3 g, and 4 g. The adsorption process was done by mixing oil with corncob adsorbent in a beaker glass. Every 20 min, turbidity was measured using a turbidimeter for 5 h. Based on the turbidimeter results, an adsorbent size of 100 mesh with a mass of 4 g has an adsorption capacity of 12,728 mg/g with percentage reduction of turbidity of 94.5%. Based on the Scanning Electron Microscope-Energy Dispersive X-ray results, the surface of the HCl-activated adsorbent has pores with a distance of 10 µm, and the adsorbent contains carbon, oxygen, silica, and copper compounds. According to the Fourier Transform Infrared results, there is a change in functional groups, Brunauer-Emmett-Teller results show a change in surface area, and Gas Chromatography-Mass Spectrophotometry results show a decrease in free fatty acids in used cooking oil after purification.

Abstract The canned motor pump has a unique design where the motor rotor and pump impeller are mounted on the same shaft, requiring careful balancing of axial and radial forces to ensure reliable operation. The use of a canned motor pump with a floating impeller system helps to balance the axial forces of the impeller, this balance ensures that the impeller is not subjected to excessive axial forces which can lead to premature wear or failure. The purpose of this study is to investigate the axial force on the canned motor pump when overheating occurs due to an operational fault in the distillation column. Investigation of the pump flow rate over 15 days showed a significant reduction in flow rate from 45,000 to 29,000 kg/h, while investigation of the pump amperage showed that the maximum amperage condition was around 54 to 60 amperes.

The distillation column plays a critical role in purifying the water–methanol mixture, with methanol being reused as a reactant in biodiesel production. However, corrosion-induced disruptions in the distillation system can lead to liquid build-up on trays, excessive vapor accumulation at the top, and foaming, which are categorized as abnormal conditions. This study aims to discuss normal and abnormal conditions in the separation process of the water–methanol mixture using a distillation column in a biodiesel plant. The novelty of this research lies in analyzing the performance of methanol-water separation in a distillation column within a biodiesel plant using lauric acid, identifying the causes of performance failure, and providing practical insights to enhance process efficiency. Data were collected via the distributed control system, capturing flowrate, temperature, pressure, and composition under both normal and abnormal conditions, with an emphasis on the effects of corrosion and column performance. The results obtained under abnormal conditions, the side-draw temperature rises to 85 °C (from 78 °C), and the distillate temperature drops to 63 °C (from 74 °C) due to excessive foaming. Methanol mass purity in the distillate decreases to 88 %, and side-draw purity falls to 61 %. The pressure difference also narrows to 0.2 bar (compared to 0.3 bar in normal conditions), and water purity at the bottom decreases to 85 %, well below the target of 99.7 %. Regular inspections of the distillation column are essential. Implementing advanced monitoring and control systems can further optimize distillation column performance and ensure the consistent quality of the final product.

Wastewater from the biodiesel process contains oil and methanol, requiring treatment to reduce chemical oxygen demand (COD) and biological oxygen demand (BOD5). Chemical separation can generate additional waste, so innovative methods like gravity separators are essential. This research uses an inlet diverter and oil collector at the distillation column bottom to treat wastewater effectively. The results show COD and BOD5 values of 210 mg/L and 80 mg/L, respectively, with percentage of removal was ±70 % and ±60 %, respectively, with 96.2 % oil recovery. Gas chromatography (GC) analysis found 2.6 % methanol and minimal impurities. This method effectively separates water-methanol-oil mixtures, making it suitable for biodiesel plants.

Biochar produced from biomass based Empty Fruit Bunches (EFB) pyrolysis presents an alternative energy source. Biomass through the pelletization process will produce bio-pellets with higher density, while microwave pyrolysis achieves better energy efficiency and cost effectiveness. This two-step process will produce a product with a longer combustion duration and higher thermochemical conversion efficiency. This study aims to utilize EFB waste through a two-step process (pelletization and microwave pyrolysis) to produce biochar as an alternative renewable energy approaching commercial standards. EFB bio-pellets with a mass of 80, 100, and 120 g were pyrolyzed in a microwave pyrolysis reactor with the power of 450, 600, and 850 W, and in time variations of 20, 30, and 40 min. The results showed that 850 W power and 80 g mass were the optimal conditions to produce biochar with the highest heating value (26.73 MJ/kg), moisture content (0.48 %) volatile matter content (12.56 %), ash content (22.33 %), and fixed carbon (64.62 %). The SEM-EDX analysis indicated that the biochar product showed an increase in carbon (C) content up to 67.4 %. It is expected that combination of the pelletization process and microwave assisted pyrolysis could become a new alternative for producing biochar that could be commercialized. This research was carried out to address the problem of accumulating EFB in palm oil mills and generating renewable energy from waste.

In Indonesia, the biodiesel industry generates approximately 48–60 tons of solid waste annually using heterogeneous catalysts. The heterogeneous catalyst's reusability is essential to addressing the issue, notably the first reaction. This research develops Amberlyst CM-4 catalyst recycling using continuous methanol washing to be used multiple times in biodiesel production with lauric acid as feedstock. The research involves the esterification, washing, and drying sections connected using self-designed vessels. The Amberlyst CM-4 catalyst was continuously reacted and reused to monitor the biodiesel conversion level. Based on the results, the Scanning Electron Microscope provides the condition of the visible pores on the surface of the fresh and used catalyst. The Fourier Transform Infra-Red results detect both C–H bonds as part of styrene, and CC was obtained from ethane of the fresh and used catalyst that is the nature of Amberlyst CM-4 catalyst. The Brunauer-Emmett-Teller confirms the change in pore surface area for fresh and used catalysts. The results of the lauric acid and biodiesel components in the Gas Chromatography show major components of C12 and C14. The recycling results show that the esterification reaction can be used up to 24th times in experiments obtained at a temperature of 80 °C and a molar ratio of 8:1. However, by the 25th experiment, the conversion was already below 80 %. The determination of the success of biodiesel production in this study is the conversion obtained ≥ 80 %. This refers to the catalyst manufacturer used in the industrial world to reduce biodiesel production costs. Hence, continuous washing of Amberlyst CM-4 catalyst using methanol could be applied in the biodiesel industry.

Pulp quality significantly affects paper products, necessitating a balance between brightness, strength, and environmental sustainability. The bleaching process, which includes delignification and brightening stages, is crucial for achieving high pulp brightness. Current pulp bleaching research emphasizes optimizing processes and developing predictive models for better quality control, yet real-time pulp brightness monitoring remains a challenge. This research developed a MATLAB program to predict pulp brightness and consistency in real-time during bleaching, conducted entirely without incurring any financial costs. Empirical models for predicting pulp consistency at the extraction-oxidative-peroxide (EOP) and D1 stages were created using second-order polynomial equations, incorporating production rate and inlet pressure as variables. Brightness increment correlations were formulated based on temperature, chemical flow rate, residence time, pH, and inlet pressure, with specific models for the preceding chlorine dioxide (DA), EOP, and second chlorine dioxide (D1) stages. Data normalization ensured efficient processing by standardizing parameter scales. Results showed relationships between brightness increment and parameters for each sub-stage such as DA is linear for pH, quadratic for chlorine dioxide (ClO2) flow rate, cubic for temperature and residence time; EOP is linear for hydrogen peroxide (H2O2) flow rate, quadratic for temperature, cubic for inlet pressure, residence time, and pH; D1 is linear for pH, quadratic for ClO2 flow rate and residence time, cubic for inlet pressure and temperature. The coefficient of determination (R2) for the DA, EOP, and D1 sub-stages are 0.85313, 0.86526, and 0.86322, respectively. Parameters with the highest contributions in each stage were identified, such as inlet pressure in the D1 substage yielding the highest brightness gain. This system offers an alternative approach for analyzing pulp quality issues and is adaptable to future mill operational needs.

Durian (Durio zibethinus) is highly consumed seasonal fruit that generates abundant waste in the form of peel. Durian peel can serve as an effective adsorbent because it is rich in cellulose–lignin. This waste has potential applications in the chemical industry, such as using durian peel to purify crude glycerol. This research studied durian peel as an adsorbent in the form of activated carbon in the purification of acidified crude glycerol. The purification process begins with the acidification process of crude glycerol using concentrated acid with a mole ratio of phosphoric acid:glycerol (n/n) of 0.5:1, 1:1, 1.5:1, 2:1, and 2.5:1. The adsorption process by carbonization and activated of durian peel using 0.1 N KOH as adsorbent with a mass percentage ratio of adsorbent:crude glycerol (%wt) of 5 %, 10 %, 15 %, 20 %, and 25 %, and stirred using a magnetic stirrer at a speed of 250 rpm for 2 h. The adsorbent utilized has a carbon-rich content of as much as 80.6 % based on Energy Dispersive X-ray analysis. The highest glycerol purity obtained at 96.26 % is achieved at phosphoric acid:glycerol mole ratio of 1:1 and adsorbent:glycerol mass ratio of 25 %. This result also matches the analysis by gas chromatography. Thus, the others test of the purified glycerol, such as density of 1.267 g/cm3, water content of 1.6 %, ash content of 0.2 %, and matter organic non-glycerol of 1.94 %, are in accordance with the glycerol standard BS 2621:1979.

Shell and Tube Heat Exchanger (STHE) is a commonly used type of heat exchanger in various industries due to its cost-effectiveness and ease of maintenance. Continuous washing and maintenance of STHE play an important role in influencing both the quality and quantity of production from biodiesel plants. In this particular investigation, the STHE serves as a cooling medium for biodiesel production, with cooling water circulating on the tube side and biodiesel flowing on the shell side. This study focuses on removing silica crust buildup caused by cooling water in the Shell and Tube Heat Exchanger. Furthermore, a Clean-in-Place machine and a 10 % citric acid solution with variable washing times of 2 h, 4 h, 6 h, 8 h, 10 h, and 12 h were used for the cleaning process. The results indicate a significant 250 % increase in the volumetric flow rate of the cooling tower along with an increase in the overall Heat Transfer Coefficient after 10 h of washing. Further analysis at the hours mark showed consistent results, suggesting a steady state. Beyond this point, no additional temperature decrease was observed, with temperature stabilizing at 32 °C. The results of the Scanning Electron Microscope analysis show that the crust formed in the STHE comes from silica found in cooling water.

Palm oil mill effluent (POME) has high levels of contaminants, one of which is Chemical Oxygen Demand (COD) of around 40,000–60,000 mg.L−1. The very high COD levels in POME are harmful in terms of toxicology and aesthetics to the environment. POME treatment by anaerobic digestion can be carried out through the Upflow Anaerobic Sludge Blanket-Hollow Centered Packed Bed (UASB-HCPB) fermentor to produce biogas, while the liquid phase will end up as effluent. However, these effluent not met the quality threshold so further treatment is required. Aerobic process can be address this issue by utilizing microalgae. Chlorella vulgaris is a microalgae that is widely used in wastewater treatment because of its resistance to pollutants and degradation effectiveness. The purpose of this research is to treat the effluent from the UASB-HCPB fermentor by utilizing Chlorella vulgaris in a fed-batch system. The novelty of this research is the utilization of microalgae of Chlorella vulgaris in photobioreactor for treating the effluent from the UASB-HCPB fermentor so that it meets the predetermined quality standards and safe to be discharged into the environment. In this study, the culturing process of Chlorella vulgaris was carried out in photobioreactor with variations of lighting intensity (12:12) and (24:0), with and without aeration. The cultivation process was carried out in the same of the photobioreactor with variation of fed-batch system with effluent addtion of 450 mL.day−1, 900 mL.2 day−1, and 1350 mL.3 day−1 with variation of agitation rate of 10 rpm, 20 rpm, 30 rpm, 50 rpm, and 100 rpm. Based on the experimental results in culturing process, it was found that the aeration and lighting process (24:0) increased the growth of Chlorella vulgaris best with an absorbance of 0.759 with the relationship between optical density and biomass dry weight with a value of (g.mL−1) = 0.008 OD + 0.0017 with R2 = 0.981. The best substrate addition in cultivation process was obtained with the addition of 900 mL.2 day−1 with absorbance 0.758 and specific growth 0.164 day−1. The best COD decomposition efficiency 87.5 % was obtained with the addition of 900 mL.2 day−1. The best agitation of 30 rpm was obtained with absorbance of 0.850 and COD decomposition efficiency of 93.75 % for 12 days cultivation. Total cost estimate offered of 11.1 IDR/L was obtained. This indicates that these conditions are effective for POME effluent treatment applications involving Chlorella vulgaris. The utilization of Chlorella vulgaris optimistically can be applied as a new low cost solution in the integration of sustainable POME treatment in the palm oil industry.

Coconut shell waste has generated environmental problems in Indonesia. Due to fossil fuel shortage, coconut shell waste has been advantaged as an energy source to replace the fossil energy. A pyrolysis technique has been used to crack coconut shell waste into charcoal or solid biochar. An MLR (Multiple Linear Regression) analysis and Lagrange polynomial interpolation has been applied to the pyrolysis process related to pyrolysis temperature and time-affected charcoal characteristics. This type of analysis often used for process optimization. The charcoal characteristics are investigated in terms of their yield, water content, ash content, volatile matter, and calorific value. The experimental result shows that the highest calorific value (≈ 7750 cal/g) was obtained at 450oC and 3h with charcoal characteristics: 2.75% water content, 2.70% ash content, and 9.50% volatile matter that meets the SNI requirements. The MLR analysis has justified that the effect of pyrolysis temperature is more dominant than pyrolysis time on almost all charcoal characteristics. The Lagrange polynomial interpolation shows the highest calorific value (≈ 7784 cal/g) obtained at 500oC and 3h. The finding applying MLR analysis and Lagrange polynomial interpolation based on experimental results is a new breakthrough in this investigation.

The widespread use of heterogeneous catalysts for biodiesel production has led to the generation of substantial waste. Therefore, it was needed to reduce the solid waste catalyst in the biodiesel industry by exploring the reuse of catalysts. This study focused on the reactivation of used catalysts through the esterification of lauric acid using Amberlyst CM-4 catalyst, with pre-treatments involving methanol washing and HCl reactivation. Gas chromatography was employed to analyze lauric acid and methyl ester while Scanning Electron Microscope provided insights into the pore conditions of the fresh catalyst and used catalyst and Brunauer Emmett Teller provided information into surface area and pore condition. In this study, it was examined how many times the Amberlyst catalyst could be used to catalyze lauric acid to become biodiesel. The limitation of this capability is catalyst conversion above 80 %. The results showed that optimal conditions for biodiesel production were reached at a reaction temperature of 60 °C, a reaction time of 120 minutes, and an agitation rate of 500 rpm, yielding 93.7 % conversion for the used catalyst and 98.5 % for the fresh counterpart. The Amberlyst catalyst can be used up to seven times, because the results still provide a conversion above 80 %. After this catalyst does not provide a conversion above 80 %, then this catalyst is washed with methanol and activated using HCl. The results obtained show that this catalyst can still be used four more times. Hence, the results of this research can be applied to reduce industrial waste and reduce the costs of making biodiesel from fatty acids.

An anionic surfactant, Sodium dodecyl sulfate (SDS), was applied to remove Cd ions as contaminants on the sand surface. The remediation operation approach was used, such as batch, flushing column without foam, and with foam of SDS solution. Increasing the SDS concentration is possible to improve the removal ability of Cd ions from the sand surface. For batch, the operation performs the higher removal ability by increasing the shaking rotation per minute (rpm). Fluctuation of the percentage removal efficiency (% RE) was shown by using a flushing column without foam at each flow rate variation. The channeling effect during flushing in the column was proved to be the cause of fluctuation in the removal efficiency. Flushing with foam is possible to increase the removal efficiency from 10% by batch and flushing without foam to about 70% with foam. The increasing flow rate of surfactant SDS solution is possible to increase the removal efficiency and flow to the intra-particle area of sand and then decrease the channeling effect. Flushing in column approach with foam by anionic surfactant SDS shows the higher ability and more efficiency in the removal of Cd ions on the sand surface.

In the purification process of used cooking oil, an adsorption technique utilizing corncob as the adsorbent can be applied. To optimize the purification, the shaking speed, adsorption time, and turbidity vary. Therefore, this study was conducted in batch operation to determine the effect of suitable adsorption and reactions on shaking speed with variations in mass, size, and the contact time of the adsorbent for 5 h. During the experiment, the used cooking oil was subjected to the adsorption process using 100 mL of adsorbent, with mass variations of 2 g, 3 g, and 4 g. The surface morphology of the adsorbent was characterized by modeling corncob and the oil components of chemical compounds contained in the used cooking oil were examined before and after purification. The parameters observed were measured using Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX), Gas Chromatography-Mass Spectrometry (GCMS), Fourier-Transform Infrared Spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET). The results showed that the adsorbent with a size of 100 mesh, a shaking speed of 140 rpm, and a mass of 4 g exhibited a higher surface area and greater adsorption capacity. Furthermore, the adsorbent also influenced the turbidity value of the used cooking oil, and prolonged contact between the adsorbent and oil led to an increase in turbidity, particularly when using adsorbents of sizes 50 and 70 mesh.

This study aims to determine the amount of catalyst and the best reaction time in making biodiesel (methyl ester) from palm fatty acids. The esterification reaction is carried out at 65 oC by using sulphuric acid (H2SO4) as a catalyst. The catalysts used varies from 5 %, 10 %, 15 %, and 20 % to the amount of fatty acid, while the acid value is measured at the reaction time of 60 minutes, 75 minutes, 90 minutes, 105 minutes, and 120 minutes. The molar ratio of methanol and fatty acid varies from 5:1, 6:1, and 7:1. The results obtained show that the acid value increases rapidly from the reaction time of 60 minutes to the reaction time of 105 minutes, and does not increase significantly from the reaction time of 105 minutes to the reaction time of 120 minutes. Based on the acid value obtained, the highest conversion of fatty acids to biodiesel is 97.1250%. This result is obtained at a reaction time of 120 minutes, the amount of catalyst 20 % of the amount of fatty acid, and the molar ratio of methanol and fatty acids 7:1, but this result is almost the same as the conversion of fatty acids at the reaction time of 105 minutes with the same amount of catalyst and molar ratio, that is 96.9286%.