*Shahrol Mohamaddan^1,2, Mohd Rizal Arshad³, Annisa Jamali¹, Helmy Hazmi⁴ and Muhammad Naim Leman⁵

¹ Faculty of Engineering, Universiti Malaysia Sarawak, 94300, Kota Samarahan, Sarawak, Malaysia

 ² Department of Bioscience and Engineering, College of System Engineering and Science,

Shibaura Institute of Technology, Japan

³ School of Electrical and Electronic Engineering, Universiti Sains Malaysia, Malaysia

⁴ Faculty of Medicine and Health Sciences, Universiti Malaysia Sarawak, Malaysia

⁵ Industrial Training Institute Kota Samarahan, Malaysia

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Abstract

According to Word Health Organization (WHO) and United Nation (UN), there is an increasing number of elderly and people with disabilities (PWD) around the world. Among the PWDs, stroke has the highest number of patients. In order to regain the functionality of the body (upper and lower limb), the stroke patient needs a consistent rehabilitation program guided by the therapist. Unfortunately, the traditional rehabilitation program is laborious and intensive especially for the lower limb (e.g. gait rehabilitation). The impact of rehabilitation program is also depending on the therapist’s experiences. The rehabilitation program is difficult to meet the requirement of high intensity and repetitive training due to the increasing number of patient and the lacking number of therapists. The development of lower limb rehabilitation robot (LLRR) is one of the solutions to support the rehabilitation program. LLRR has been used to regain the muscle strength and to support the patient’s mobility. In this research, LLRR with the home-based concept will be developed. The ‘compact and mobile’ LLRR is expected to be used by the rural community in Sarawak. The research starts with kinematic and dynamic analysis of the LLRR. Based on the analysis, design and fabrication of the LLRR will be conducted. The novelty of this research will be on the adaptive control system that will be implemented on the developed LLRR. The control system will ensure that the LLRR is more flexible and adjustable based on patient’s condition, progress and participation. In the era of Industrial Revolution 4.0, this research is hoping to support the community in Sarawak by providing the robotics solution for biomedical application.

Lidyana Roslan¹, Shahrol Mohamaddan¹, Annisa Jamali¹, Saidatul Ardeenawati²

¹ Faculty of Engineering, Universiti Malaysia Sarawak, 94300, Kota Samarahan, Sarawak, Malaysia
² School of Biomedical Electronics Engineering, Universiti Malaysia Perlis
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Abstract

The human foot plays an important role in human motion such as standing, walking, running, jumping, balancing, and also helps to withstand the force from body parts. Every person has a gait, or manner of progressive locomotion which is peculiar to that individual (Boehler, Hollander et al., 2008). However, one can have an abnormal gait due to certain disease like foot drop syndrome. The patient tends to walk with an exaggerated flexion of the hip and knee to prevent the toes from catching on the ground during the swing phase. As a result, the force of the heel strike exceeds body weight and the direction of the ground reaction vector passes behind the ankle and knee center throughout the gait. This is because foot drop occurs from a muscular condition caused by problems with the common peroneal nerve or paralysis of the muscles in the anterior region of the lower leg. Some of the most common diseases that can cause foot drop include direct hit to the back of the knee, muscular dystrophy, multiple sclerosis, and cerebral palsy. Complications in a replacement surgery or knee ligament reconstruction surgery may also cause this problem.

To fix the problem, AFO (ankle-foot orthosis) is introduced to patients diagnosed with weakness in the lower limb (Mohamaddan, Ishak et al., 2018). The AFO is a device or brace that covers the foot, ankle, and part of the leg (Chin, Hsiao-Weckler et al., 2009). The approach of AFO is to mechanically lift the foot without trying to replace the muscle action. The device is used to correct the instabilities and joint weaknesses of the lower limb muscle (Kao & Ferris, 2009). AFO was able to improve mobility and can be used as rehabilitation devices to correct the motor patterns (Park, Chen et al., 2011). Moreover, the AFO may improve the walking pattern performance of the user by proper control motion of the device (Peckham & Knutson, 2005). However, AFO is considered bulky in size and only offered a passive approach.

On the contrary, FES (functional electrical stimulation) offers an ‘active’ approach where human muscles and nerves are stimulated that imitates for rehabilitation exercises on targeted muscles to retrain the ‘muscle memory’. FES is the application of electrical current to excitable tissue to supplement or replace function that is lost in neurologically impaired individuals. FES is the application of electrical current to excitable tissue to supplement or replace function that is lost in neurologically impaired individuals (Everaert, Thompson et al., 2010). By using the body’s muscles nerves, there can be some rehabilitation from exercise, and muscle memory can be rebuilt. Therefore, FES can be used in many clinical applications to restore upper extremity, lower extremity, bladder and bowel, and respiratory function. This is why FES is defined as an active approach for lower limb rehabilitation. Likewise, FES is also considered lighter in size compared to the existing method of using AFO. Figure 1 shows the comparrison between a 3D printed APO and a commercial FES walk stimulator.

Figure 1: Left: 3D printed AFO. Right: Commercial FES walk stimulator (Retrieved from Amazon).

The objective of this research is to study the suitable and important human muscle parameters by using FES for lower limb rehabilitation in the effort to find suitable and important human muscle parameters that can improve the lower limb rehabilitation. The understanding of human muscles and their characteristics provides a platform to design the FES circuit and algorithm. By proper placement of the surface electrode on the lower limb, designing the mechanical switch for the overall system, and control the current or voltage for the stimulator, the goal is to reduce pain or discomfort. To achieve this, three important parameters; pulse frequency, amplitude, and duration will be manipulated for stimulation to acquire maximum muscle contraction. The locomotion experiment will be used to study the gait pattern (plantarflexion and dorsiflexion) to validate the finding. This includes manipulating those parameters to control the strength of muscle contraction.

The research outcome is expected to have efficient stimulation (lowest stimulation with the strongest contraction) with lower electrode leads and at the same time reduce pain or discomfort to the patient. The finding may contribute to further understanding of human muscle and propose new methods such as combining the passive and active approach in supporting lower limb rehabilitation.

This research is aligned with the Sarawak Digital Economy Strategy 2018-2022: To increase accessibility and improve the level of medical and health services in rural and remote Sarawak and promote world-class health tourism. The study is supported by Sarawak Research and Development Council. 

Chee Khoon Ng, Hoo Tien Nicholas Kuan, Leonard Lik Pueh Lim, Sim Nee Ting, Idawati Ismail

Faculty of Engineering, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia

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Abstract

The ferrosilicon and manganese alloys production in Samalaju Industrial Park generates abundant of by-products known as silica fume and manganese slag. These by-products are categorised as scheduled wastes by the Department of Environment (DOE). Manganese slag has been found to posses pozzolanic properties and therefore suitable for usage in concrete mix. This proposed research will focus on utilising these waste materials in the production of concrete and/or geopolymer concrete. The mechanical and durability properties will be determined for the optimum mix of maganese slag-cement concrete and geopolymer concrete. Leaching test will also be carried out to identify the environmental impact of using these types of concrete in building construction. A life-cycle cost analysis will also be carried out to compare the cost of using maganese slag-cement concrete and/or geopolymer concrete compare with conventional concrete in building construction.

The use of manganese slag as pozzolanic material in concrete mix is still very profound to the best knowledge of the authors. The percentage of ordinary Portland cement that can be replaced by manganese slag without compromising the material properties of concrete remain unknown. Furthermore, the research on manganese slag in geopolymer concrete is even more scarce. The ferrosilicon and manganese alloys production in Samalaju Industrial Park generates abundant of by-products known as silica fume and manganese slag. These by-products are categorised as scheduled wastes by the Department of Environment (DOE). If the manganese slag is found to be applicable in cement blend and concrete production through this research, then the benefits are two-fold, i.e., recycling waste and wealth creation.

Some preliminary studies on utilising silicomanganese slag as replacement material had been carried out by Frias et al. (2006) and Altun & Yılmaz (2002) with 5% to 45% of replacement. It was found that the 7^th day compressive and flexural strengths of the mortars had been compromised by 10-25% but the effect was less profound at 28^th and 90^th day strengths. It is important to note that this study was carried out on mortars with limited variation on percentage of replacement. Therefore, there is still a need in research of actual concrete behaviour with more variation in replacement percentage in order to utilise this waste material (manganese slag) efficiently.

In a separate study conducted by Wang (2017), it was found that manganese slag mixing with fly ash has a potential application in geopolymer concrete through alkali activation. However, this study only provides preliminary results indicating the potential use. Therefore, further investigation into utilising manganese slag in geopolymer concrete is still a necessity.

On durability aspects, Ganesh et al. (2018) reported that when the coarse aggregate of concrete was replaced with 50% of manganese slag, the strength and durability aspects of the concrete were not compromised. However, this study did not use manganese as replacement of Portland cement and the results cannot represent research on using manganese slag as pozzolanic material. Liu et al. (2012) conducted a research on manganese slag-cement concrete and found that it has improved on both seawater and freezing-thawing resistance. To the best knowledge of the authors, there is no research on leaching characteristics of manganese slag-cement concrete. Due to the high content of heavy-metal oxide in manganese slag, it is envisaged that leaching of heavy metal from this type of concrete posts environmental impact. Therefore, it is an important aspect to investigate if this type of concrete is going to be used in building construction.

The optimum replacement percentage of Portland cement with manganese slag without compromising the mechanical and durability of concrete and/or geopolymer concrete can be identified. The effect of leaching will also be present to study on the effect of environmental issue.

Shahidul Islam, Mohd Azrin Mohd Said, Rubiyah Baini, Shirley Johnathan Tanjong
Faculty of Engineering
Universiti Malaysia Sarawak
 Kota Samarahan, Sarawak, Malaysia

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Abstract

This research project focuses on building a pilot plant with anaerobic reactor (AR) and Nano membrane filtration (NMF), and to investigate the performance of the pilot plant in producing biogas and water from the palm oil mill effluent (POME). The broad objective of the work is  to model an economically and environmentally sustainable solution for POME treatment, in line with three sustainable development goals: SDG-6 (clean water), SDG-7 (clean energy), and SDG-13 (climate actions). The proposed pilot plant is designed based on findings of several laboratory-scale experiments, using a  batch  anaerobic reactor (BAR) with C/N enriched inoculum for digesting the total organic material (TOM) of POME and using Nano membranes for separating TOM from effluent of BAR. The BAR will be operated at temperature 35⁰C with various range of manipulating variables for digesting TOM. The Nano membrane will be operated at feed pressure range from 60 to 120 psi for separating TOM from the effluent. The findings of this research would be useful in optimizing the  biogas  and water  production from POME. The novelty of the proposed research is to use a ‘two stage anaerobic reactor and nano membranes in series for optimizing the performance of POME treatment in lign with expected contribution to achieve the UN Agenda 2030.

 

Keywords: Palm Oil Mill Effluent,  Anaerobic Digestion,  Waste to Energy [WtE],  Production and Productivity, Nano- Membrane; Environmental Sustainability, Climate Change

 

1.0    Background of Water Resource Recovery from POME

Malaysia currently accounts for 39 percent of world palm oil producer (17.73 million tons) which is about 44 percent of global export market share.  The average earning of Sarawak’s palm oil industry is about RM 8.0 billion per year contributing to the state economy especially in the aspect of employment generation and economic growth.  The challenges faced by palm oil industry are potential carbon emission and pollution from solid biomass and POME, which possibly contributes to climate change (Shahidul et al. 2019; Eugene et al. 2019).  Currently,  palm oil mills have been using several types of anaerobic digester, and it was reported that the biogas and quality effluent production performance was appeared to be poor and not technically and financially feasible to be used  (Ahmed et al. 2015; Chan and Chong 2019; Shahidul et al. 2018). It has been widely claimed that  due to the poor performance of anaerobic digesters,  the palm oil mills are reluctant to install anaerobic technology (Ahmed et al. 2015; Chan and Chong 2019); thereby the mills continue using the traditional POME treatment method (Jefferson, Kanakaraju, and Tay 2016). It has also been found that there is a research gap exists in POME treatment in reducing TOM. Indeed, this research is done to reduce the research gap in improving the performance of  anaerbic reactor, and also to produce water and biogas from POME in lign with expected contribution to achieve SDG-6(Clean water for all), SDG-7(clean energy) and SDG-13( climate actions) towards achieving  the UN Agenda 2030 (United Nations 2015).

 

 

1.1       Current State of the Art of POME Treatment  

Biodegradation of POME produces methane (CH₄), carbon dioxide (CO₂) and hydrogen sulphate (H₂S) that are emitted to the air as greenhouse gas (GHG). In order to minimize GHG emission, several types of AR have been used to digest TOM. It has been reported that the C/N, pH, HRT, SRT, temperature and OLR of substrate inside the AR plays a  vital role in decomposing TOM  for producing  biogas (Ahmed et al. 2015; Chan and Chong 2019; Iskandar et al. 2018).   

 

1.1.1 Performance of Anaerobic Reactor in POME treatment

Eugene et al. (2019) and Abdelgadir et al. (2014) have conducted studies to reveal the effect of pH (from 6.9 to 7.5) on TOM reduction from POME. The findings demonstrated that performance of anaerobic reactor has a positive effect on anaerobic digestion process .The published reports have also demonstrated that the anerobic digestion of POME leads to acidic and toxic environment in the anerobic reactor with pH less than 6.6, which  negatively associated with digestion process and biogas production  ((Abdelgadir et al. 2014; Eugene  et al.2019).

 

Siddique et al. (2016) and Poh and Chong (2009) revealed that at higher HRT (4<HRT<8) in anaerobic process, the contact time between microbial communities and organic substance increase which contributed to the increasing of digestion performance of substrate and result in the increasing of biogas production  and quality effluent from POME ( Seman at el. 2019; Shahidul  et al.2018; Siddique et al. 2016).

 

Eugene et al. (2019) and Abdelgadir et al. (2014) stated that SRT has a positive and significant (p-value<0.05) effect on TOM digestion, and it is effective between SRT 13 days to 20 days. It was also reported that beyond that time limit,  the TOM utilization rate in digestion process would reduce; Abdelgadir et al. (2014), Halalsheh et al. (2005), Shahidul, Malcolm, et al. (2018), Krishnan et al.(2017), Mao at el.(2015) and Nayono (2010) revealed that in POME treatment process, the OLR is positively associated with anaerobic digestion process and has a significant effect (p-value<0.05) on biogas production from TOM. It was stated that at OLR higher than 5.0 g.m^-3. d^-1, the biogas production tends to reduce; and at much lower than (≤ 3.5 g.m^-3. d^-1), the digestion perfromance  also tends to reduce (Fang et al. 2011; Krishnan et al. 2017; Malakahmad and Yee 2014; Mao et al. 2015; Nayono 2010).

 

It was stated that the carbon to nitrogen ratio (C/N) between 26 and 32 is required to provide  optimum level of carbon and nitrogen for anaerobic bacteria growth in the digestion  process (Nurliyana et al. 2015). At lower C/N (C/N<26), the nitrogen concentration in the digestion process get higher contributing to acidic environment. At the higher C/N (C/N>35), the nitrogen concentration in the digestion process suffer lack of nitrogen and tends to reduce the activities of the bacteria. In both cases, the anerobic proecss exhibits a poor perfromance in TOM digestion (Esposito et al. 2012; Eugene, J. J, Shahidul, M. I., & Mamunur 2019; Nurliyana et al. 2015; Zakarya et al. 2016).

 

Membrane technology (NMF) has been given priority by scientists and engineers in recent years as a tool for separating dissolved solids from bio-fluid.  The NMF  has been successfully used  in  water prodcution  from  wastewater  as well (Fakhru’l-Razi 1994; Liew Abdullah et al. 2005). However, Abdurahman et al. (2011) and Espinoza-Gómez (2003) revealed that membrane technologies specially NMF is a potential separation means for reducing dissolved solid from bio-fluid like POME (Heriberto   et al. 2004;  Abdurahman  et al.  2011).

The literature review concludes that the performance of anerobic digester depends on pH, HRT, SRT, C/N and OLR. All these manupulating variables have both negative and positive effect on the performance of anerobic digestion process in converting TOM to biogas and to produce dischargeable effluent from POME.

 

 

2.0 Problems in POME Treatment and Research Objective

The  global production volume shown that the  CPO potential is about 74.0 million metric tons in a year  (Shahbandeh 2020). Malaysia shares about 40% of  global CPO.  Indeed, the CPO processing is an identified GHG emission source and a primary driver of climate change. In Malaysian perspective, the carbon (CO₂eq) emission potential of POME is approximately 28m³ per ton of POME . It was reported that carbon (CO₂eq) contains about Methane (CH₄ ≥65%) which is source of biogas based energy. The  estimated energy potential of POME in Malaysia is  about 13,600 MWh per Year (Shahidul and Malcolm, 2018).

 

However, a few palm oil mills have been using anaerobic digester for converting POME into biogas and dischargeable effluent, but the success records are not satisfactory. It is also reported that a few mills are discharging poor quality effluent to the environment due to lack of required technology. However, it was found that palm mills are struggling to comply with the  environmental regulations and they need an affordable and efficient technology for POME treatment (Seman  et al., 2019; Shahidul and Malcolm, 2018). A few researches have reported that the performance of  AR  in  POME treatment is less than 65% (Eugene, et al, 2019; Ng et al. 2012; Shahidul, et al., 2018).  However, the reported problem in palm oil mill domain demonstrated that in many cases, the process used for decomposing TOM  is not fully able to meet the requirement of the Department of Environment(Eugene et al.,   2019; Ng et al. 2012; Shahidul et al. 2020; Shahidul et al.2018). Indeed, this research is designed to address TOM reduction problem  from POME to produce biogas  and recyclable water, and the main objective is to build a pilot-scale plant with AR and NMF; the Biogas and fresh water potential  from  POME will be determined .

 

3.0 Research Methodology

The research activities will be divided into two parts. In the first part, BAR will be used for the digestion process of TOM to produce biogas and effluent. In the second stage, Nano membranes will be used to separate TOM from the Bar’s effluent. The methodology included are sample (POME) collection, pilot-scale plant setup and experiments according to design experiments from Design Expert (version 2018) software, inputs-outputs data collection of experiments, and data analysis. The Design of Expert (version 2018) software  (DOE) will be used to estimate the required experimental runs (Chan and Chong 2019), and to analyse experimental data. 

 

3.1 Experimental Setup

Figure 1 shows the experimental setup that includes major parts such as the feed stock tanks, pumps, BAR and NMF.

 

Figure 1: Machinery  of pilot plant with Bar and NMF

3.2 Membrane Setup for Waste Biomass Separation from Effluent

Three NMF  will be  used, and similar membranes have also been used by several researchers in solid separations process from effluent ( Espinoza et al., 2001; Heriberto at al., 2003; Heriberto  at al., 2004). The properties of  NMF  are listed in Table 1.

 

Table 1: Properties of Nano Membrane Used

Membrane Type	Surface Areas	Pore Diameter (nm)	Membrane CODE	Hydraulic Permeability (10-14 m)
NF270-4040	7.6 m2	≈0.8	NMF1	0.899
NF90 4040	7.6 m2	0.68	NMF2	0.929
GE NF4040	6.5 m2	0.10	NMF3	0.699

 

3.3 Research Variables 

The independent research variables are HRT, SRT C/N, pH and OLR.  The range of independent variables and experimental runs will be estimated by using DOE (Chan and Chong 2019).

 

3.4 Method of Conducting Experiments

Feedstock will be prepared with  C/N enriched  inoculum. The pH in the substrate will be adjusted by adding sodium hydroxide (NaOH) (Choi et al. 2013; Eugene,  et al. 2019). The BAR1 will be used for hydrolysis and acidogenesis and it will be operated at pH 5.0 and temperature of 35℃ for 2 days  [HRT 2 days] in order to break down the long chain organic materials into short chains (Eugene et al., 2019;Mamimin et al. (2015;  Kim et al. (2015). In  BAR2, the acetogenesis and the methanogenesis processes will be  performed at pH from 6.5–7.5 and temperature of 35℃. The HRT, SRT and OLR will be varied based on the DOE estimate (Fang et al. 2011; Halalsheh et al. 2005; Mahmoud et al. 2004; Malakahmad and Yee 2014).

 

Effluent of BAR will be fed to NMF for clean water production. The feed pressure and cross flow velocity  of effluent  will be determined from the NMF’s manufacturers operations manual. The outputs of NMF such as the volume and dissolved solids of concentrates and permeate,  will be determined as per the  method suggested by Van  and Olieman  (1991).

The concentrated parts of effluent (m_f) enriched with TOM will be recycled through BAR1, BAR2 and NMF. The data of TOM, biogas and water will be collected from  BAR and NMF, and  will be analysed to achieve research objectives. 

4.0       Expected Research Outcomes, Benefits and Implications

The estimated outputs from the pilot plant are 0.30m³ biogas per m³ of POME and 0.6m³ water per m³ of POME. The outcomes of the proposed research have some practical benefits to the society in achieving economic and environmental sustainability. The project will contribute to develop human capital with required knowledge to address the challenges with POME treatment related to carbon emission and air pollution which are contributing to climate change.

 

4.1       Implications of Research Outcomes

The findings of this research are expected to have  a few implications in economy, health and environment aspects in Sarawak. The technologies and methods proposed in this research  would be a guideline in recovering waste biomass and organic material from POME for reducing carbon emission (CO_2eq). Additionally, the method described in this paper would be useful to increase the quality of dischargeable effluent which would contribute to reduce the pollution in the air, water and soil. These findings would be a useful reference for engineers and researchers working with palm oil mills to provide quality service in achieving higher efficiency in  producing biogas and quality effluent from POME.  

 

5.0       Research outcomes and Conclusion  

The pilot plant will be developed and operated based on the outcomes of several laboratory scale researches conducted since 2013. The expected outcomes  from the  pilot plant would contribute to establish a solid path to recover clean water resources from hazardous POME. The outcomes would also be a guidline for engineers and industries to design the process for producing quality effluent from  POME. The proposed pilot  plant would be a model to produce commercial scale POME treatment plants that is expected to contribute in the achievement of  economic and environmental sustainability in the state of Sarawak.

 

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