Is the dewatering of Palm Oil Mill Effluent (POME) feasible? Effect of temperature on POME's rheological properties and compressive behavior

The current treatment process of Palm Oil Mill Effluent (POME) has been a cause of concern over recent years as POME is known to cause greenhouse gas emission as well as water pollution. An alternative for POME treatment process optimization is to eliminate the conventional cooling ponds and introduce a dewatering device such as a thickener. The thickener will assist in the solid-liquid separation, removal of microbes and other impurities from the wastewater. The latter will contribute to making the anaerobic digesters used to treat POME more efficient by allowing a means of control on the digesters’ load. However, to be able to design and predict the performance of the thickener unit; essential rheological properties of the suspension have to be determined. The rheological characteristics and the compressive behavior of POME have not been studied previously nor has the implementation of such a dewatering device in the POME treatment process. This paper attempts to bridge the gap on the rheological characteristics, the compressive behavior and the effect of temperature on the rheological properties of POME through batch settling and batch filtration experiments. Data such as the compressive yield stress, the hindered settling function, and the diffusivity function for POME have been extracted and evaluated

INVESTIGATION ON THE EFFECT OF SHAPES ON THE DRYING KINETICS AND SENSORY EVALUATION STUDY OF DRIED JACKFRUIT

Jackfruits are seasonal and highly nutritional fruits indigenous to the Southwestern rainforests of India. However much of the produce are spoilt annually due to poor preservation techniques. Minimal studies have been conducted on the drying kinetics of jackfruit and the effect of shapes on the drying kinetics. In this research, drying curves of three different shaped jackfruit slices were obtained using a convective oven at 40oC, 50oC, 60oC and 70oC. Modified Midilli-Kucuk Model was found to be the best kinetic model for drying of jackfruits. At all temperatures, effective moisture diffusivity values and activation energy varied from 2.66 x 10-10 - 4.85 x 10-10 m2/s and 16.08 - 20.07 kJ/mol respectively. Drying was found to be most efficient at 50oC using the square shaped slices with a R2, RMSE and SSE value of 0.9984, 0.01127 and 0.002668 respectively.  Sensory evaluation of untreated and additive-added dried jackfruit slices was conducted by 40 untrained sensory panelists. Jackfruit with ascorbic acid and sugar coating had highest aesthetics value due to better retention of colour by ascorbic acid. However sugar coated jackfruit had the most favorable taste and smell. Further optimization must be done to satisfy consumers collectively to enable a highly marketable product

The influence of different solid-liquid ratios on the thermophilic anaerobic digestion performance of palm oil mill effluent (POME)

An alternative method was proposed to optimize the treatment process of palm oil mill effluent (POME) in an effort to address the poor removal efficiencies in terms of the chemical and biological oxygen demand (COD and BOD), total suspended solids (TSS) as well as oil and grease (O&G) content in treated POME along with many environmental issues associated with the existing POME treatment process. The elimination of the cooling ponds and the insertion of a dewatering device in the treatment process were recommended. The dewatering device should enhance the anaerobic digestion process by conferring a means of control on the digesters’ load. The objective of this study is to identify the optimum solid: liquid ratio (total solids (TS) content) that would generate the maximum amount of biogas with better methane purity consistently throughout the anaerobic digestion of POME, all while improving the treated effluent quality. It was established that a 40S:60L (4.02% TS) was the best performing solid loading in terms of biogas production and methane yield as well as COD, BOD, TSS, and O&G removal efficiencies. Meanwhile, at higher solid loadings, the biogas production is inhibited due to poor transport and mass transfer. It is also speculated that sulfate-reducing bacteria tended to inhibit the biogas production based on the significantly elevated H2S concentration recorded for the 75S:25L and the 100S loadings

The impact of thermal pretreatment on various solid-liquid ratios of palm oil mill effluent (POME) for enhanced thermophilic anaerobic digestion performance

An advancement to the treatment process of palm oil mill effluent (POME) was proposed whereby a pretreatment technology and a dewatering device are introduced into the existing treatment process. Thermal pretreatment is a robust technique with the ability to enhance the rate and increase the biogas production of anaerobic digestion. The dewatering device will confer a means of control on the digester's load, allowing the removal of microbes and impurities as well as assist in the residual oil removal. The proposed advancement to the treatment process allows the removal of cooling ponds making the treatment process more sustainable in terms of the substantial reduction in the amount of greenhouse gas emission, improved residual oil removal efficiency in the waste stream, and better treated effluent quality. However, to be able to implement this innovative treatment method effectively, it is fundamental to know how thermal pretreatment undertook on the solid content of POME impacts on the anaerobic digestion process performance. To conduct the study mentioned above, POME was pretreated at 120°C and was allowed to settle to separate the settled suspension and the clear liquor phases (hereafter denoted “solid” as S and “liquid” as L). Batch thermophilic anaerobic digestion was conducted on various solid: liquid ratios (i.e., the 20S:80L, 40S:60L, 50S:50L, 75S:25L, and 100S). It was found that the optimal ratios were 20S:80L and 40S:60L, which generated approximately 9-fold and 6-fold higher methane yield, respectively, in contrast to their untreated counterparts. Thermally pretreated 40S:60L solid loading exhibited a higher removal efficiency in terms of chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solids (TSS), and oil & grease (O&G), a higher methane yield of 328 mL CH4/g CODremoved and biogas production of 1886±21 mL from a working volume of 100 mL compared to all the other pretreated and untreated ratios

Applicability of various pretreatment techniques to enhance the anaerobic digestion of Palm Oil Mill Effluent (POME) : a review

Palm Oil Mill Effluent (POME) is a potential source of renewable energy. With the intensified energy demands in various industries, if the biogas production from POME treatment can be sustained, the palm oil industry can be made more environmentally and economically sustainable. The current POME treatment process is ineffective in removing residual oil and creates a large amount of greenhouse gas emissions. Furthermore, the limitation of the treatment process is the instability of the anaerobic digestion stage, which is affected by various operating parameters. Subsequently, the chemical and physical characteristics of POME vary depending on different factors, such as the harvest season and the efficiency of the palm oil extraction process. Therefore, having an effective pretreatment system can radically reduce the load on the anaerobic digesters, sustain biogas production, and enhance the treated effluent quality so that it can conform to the stringent environmental standards. The focus of this paper is to review the pretreatment methods (treatments undertaken prior to anaerobic digestion, which contributes to enhancing the hydrolysis step). A comparison of various types of sludge will be carried out to allow a thorough understanding of the impacts of these pretreatment methods and the suitability of their implementation for POME treatment. It was established that thermal pretreatment has bene proven to enhance solubilization, biogas production and the quality of the treated effluent. The increase in biogas production can easily compensate for the energy added to the system

Enhancing the biogas production and the treated effluent quality via an alternative palm oil mill effluent (POME) treatment process : integration of thermal pretreatment and dewatering

To address the limitations associated with the disposal management and the treatment process of POME, an alternative process that consists of eliminating the cooling ponds and integrating a pretreatment technology combined with a dewatering device was proposed. Since the proposed treatment process has not been tested previously, the objective of this study is to investigate the effect of thermal pretreatment and solid loading alteration via dewatering on a thermophilic continuous set up consisting of an upflow anaerobic sludge blanket – hollow centered packed bed (UASB-HCPB) bioreactor. It was established that the best performing solid loading was the 40S:60L, which is made up of 40% by volume of POME settled solids and 60% of clarified liquid. Thermally pretreated 40S:60L solid loading had a significantly enhanced biogas production, methane purity, chemical oxygen demand (COD), biological oxygen demand (BOD), and total suspended solids (TSS) removal efficiencies. The reactor exhibited stability owing to the low volatile fatty acid/alkalinity ratio obtained throughout the run. With a reactor capacity of 5L, thermally pretreated 40S:60L achieved a daily biogas production volume of 48L and a methane purity of 77.2%. The COD, BOD, and TSS removal efficiencies of the thermally pretreated 40S:60L solid loading were evaluated to be 97.5, 95.1, and 94.5%. The enhanced process performance is due to the consistent solids concentration, which allowed a more effective mass transfer and transport in the medium. Meanwhile, thermal pretreatment promoted cell lysis, making the intercellular organic matter readily available for the bacteria consortium

Water literacy in the southeast asian context:Are we there yet?

The water situation in Southeast Asia has changed from one of relative abundance to one of relative scarcity. Conventional water management that strategized around the provision of adequate water supply to users has limited sustainability. Though nations in this region have adopted the United Nations Sustainable Development Plan into their water management framework, successful outcomes are limited thus far. Water literacy has a growing importance for improving water sustainability, especially in developing countries. A literature search was employed to extract data on the different dimensions of water literacy in Southeast Asia including the sources and consumption patterns, water governance and management, and sociodemographic elements as well as the various aspects of water related challenges faced. Results from the review and analysis show that a large proportion of Southeast Asian populations are not part of a water sustainable society, and this presents a major hurdle for the countries to meet United Nations Sustainable Development Goal 6 by 2030. Therefore, active cognitive engagement through the creation of a water literate environment is critical for breaking the chain of water illiteracy and to achieve long-term water sustainability in Southeast Asia countries. Overall, this paper provides a critical analysis on lessons learnt from the region that can be mirrored in other parts of the world

A technoeconomic analysis of sewage sludge valorization for carbon emission reduction

Sewage sludge (SS) is a residual resulting from wastewater treatment that contains both organic and inorganic materials. Nowadays, SS management is a major issue owing to economic considerations and environmental pressure. It has been reported that the current sludge-to-landfill method would pose potential risks to human health and the environment. The incorporation of sustainable sludge valorization techniques (SVTs) into the SS treatment process could be a promising solution by transforming SS into value-added products, which mitigates the environmental impact of SS disposal. However, the selection of the most optimal process pathway from various SVTs is a challenging task. Hence, this paper proposes a mathematical optimization framework to determine the most sustainable SVT pathway using a single objective function of total annualized cost (TAC) minimization with the consideration of carbon pricing. A case study is conducted to evaluate the performance of the optimized SVT pathway compared to the conventional sludge management practice using different SS sources: (1) domestic sewage sludge and (2) a mixture of industrial sludge and domestic SS. The results reveal that the SVT pathway, which includes anaerobic digestion (AD) and followed by land application, is the most ideal route for domestic SS feed. For mixed SS feed, AD followed by landfilling is preferred due to the presence of hazardous constituents in mixed SS. Sensitivity analysis is performed to study the effect of SS quantity and carbon pricing on the SVT selection. It is expected that this study could provide critical insights into the development of a sustainable SS treatment process.</p