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Since the introduction of polymer banknotes, they have become a new tool for corneal foreign body (CFB) self-removal. Being easily available, lightweight, and sturdy, polymer papers have become a popular and innovative method to dislodge CFB. Although ophthalmology services are easily accessible in Malaysia, ignorance, lack of health awareness, and the desire to avoid medical costs are among the reasons why patients remove CFB themselves. The sequalae span from only a faint scar with relatively good vision to total blindness. Our case series highlights three cases of CFB self-removal using polymer banknotes and their sequalae. To echo what has been known previously, self-awareness and occupational hazard education remain the most important and effective way to prevent vision loss.

Palm oil mills generate a large amount of wastewater, known as palm oil mill effluent, during the production of crude palm oil. The high organic contents in palm oil mill effluent have an excellent potential for biogas utilisation. Besides, such effluent must be further treated before discharge or reused in milling processes. In this respect, an integrated biogas and wastewater treatment system should be developed. The aim of this paper is to synthesise and optimise an integrated biogas and wastewater treatment system via a process systems engineering tool that yields maximum economic performance. To illustrate the proposed approach, a typical palm oil mill case study in Malaysia is presented. The variation in palm oil mill effluent availability is considered to evaluate the changes in performance and ensuring the flexibility of the developed system. As shown in the results, implementation of integrated biogas and wastewater treatment system in a typical 60 t/h mill in Malaysia could export up to 1.9 MW electrical power on average. Alternatively, 110,800 GJ/year of compressed biomethane can be produced when feed-in to the national grid is not available. The implementation of integrated biogas and wastewater treatment system successfully reduces greenhouse gas emissions by 50,430 t CO2e/year as compared with the conventional open ponding system practiced in the industry. Lastly, feasibility studies and strategies to promote biogas utilisation in the industry are performed.

A carotid-cavernous fistula (CCF) is an arteriovenous fistula with an abnormal connection between the carotid artery and cavernous sinus that can be sight and life-threatening. The conjunctival injection is often the most prominent feature, and patients are commonly misdiagnosed for other ocular conditions leading to a delay in diagnosis and treatment. All three patients in this case series presented with persistent red eyes. They were all treated for conjunctivitis and only referred for further workup when other progressing ocular symptoms occurred. The diagnosis of CCF was confirmed with digital subtraction angiography and with successful endovascular embolization, their ocular symptoms resolved with preserved optic nerve function. A high index of suspicion in patients presenting with an atypical red eye is very crucial for timely diagnosis of CCF.

Endogenous Klebsiella pneumoniae panophthalmitis commonly affects those with compromised immunity. The occurrence of this infection in healthy individuals is rare. We describe the case of a healthy adult who presented with endogenous Klebsiella pneumoniae panophthalmitis from an asymptomatic liver abscess. A 64-year-old, previously healthy gentleman presented with rapidly progressive left eye periorbital swelling and blurring of vision. He had a low-grade fever three days prior to the development of ocular symptoms, but otherwise no other systemic complaints. Visual acuity was light perception in the left eye, and ocular motility was restricted in all directions of gaze. Ocular examination revealed proptosis, severe conjunctival chemosis, hazy cornea, and fibrin deposition in the anterior chamber. The posterior segment could not be visualized. Ultrasound of the hepatobiliary system revealed an abscess in the right lobe of his liver. His blood cultures grew Klebsiella pneumoniae. Despite being treated with high-dose intravenous antibiotics, his eye condition deteriorated. Evisceration was performed when he developed scleral melting and globe perforation. We highlight the importance of a high index of suspicion of endogenous Klebsiella panophthalmitis as it can be easily missed in healthy adults. Early diagnosis and prompt management are needed to prevent morbidity and mortality from this devastating infection.

Purpose To describe the epidemiology of open globe injuries and its prognostic factors from the perspectives of a tertiary care centre in northern Malaysia. Methods A retrospective study of open globe injuries in a period of three years between June 2017 and May 2020. Patients presenting with open globe injuries were identified and recruited from hospital census. Case records were retrieved and analysed after recruitment. Results A total of 114 patients with 118 open globe injuries were included in the study. Four patients had bilateral eye involvement. Men were found to have seven and a half times higher rate of ocular injuries than women. The predominant age group of ocular trauma presentation was in younger adults between the age of 21 and 30 years old. Work-related injuries account for almost half of the globe injuries (48.7%) followed by motor vehicle accident-related, domestic accident-related, and others. The significant factors related to the visual outcome are presenting visual acuity (VA), presence of relative afferent pupillary defect (RAPD) and vitreous loss. Conclusion The factors related to visual outcomes in this study may aid the clinician in determining the visual prognosis of ocular injuries. Young working males were the most susceptible group to sustain penetrating ocular injuries due to their job nature. Health education and safety at workplace are essential to reduce the occurrence of ocular injuries.

Background: A diagnosis of ankylosing spondylitis (AS) is challenging and often delayed despitebpatients being symptomatic. Low back pain is the most common initial symptom, appearing in the second and third decades of life. Acute anterior uveitis (AAU) occurs much later in the course of the disease, often when the destruction of the spine is already debilitating. Objective: Here, we report three cases of AS that were diagnosed after the patients developed AAU. Methods: A case series illustrated AAU leading to the diagnosis of AS years after the initial episode of low back pain. A comparison of the clinical presentation, diagnosis, and outcomes was also illustrated. Result: We report three cases of acute anterior uveitis (AAU)-associated AS diagnosed only after many visits to the primary health care provider with the complaint of chronic low back pain. All three patients had irreversible radiological changes upon diagnosis of AS. The AAU resolved with topical steroids, and one patient developed cataract. Conclusion: A high index of suspicion of AS in a young adult with chronic back pain before the development of AAU may prevent further functional loss and provide a better prognosis. Diagnosis of AS following AAU is not only associated with dependency but also may rob the vision of a young adult.

Purpose: To investigate the prevalence of fundus and macular optical coherence tomography (OCT) findings, and the spectrum of dengue-related fundus presentation in a Malaysian tertiary hospital. The associations between platelet count and haematocrit level with fundus and macular OCT findings were also investigated. Design: Cross-sectional study. Methods: The study was conducted at Hospital Raja Permaisuri Bainun, Ipoh, from June to August 2015. Patients who consented to participate underwent a comprehensive ocular examination. Examination included a best-corrected distance (6 m) and near visual acuities, standard black-on-white Amsler chart testing, pupillary light reflex, fundus examination, followed by dilated fundus photographs and OCT of the macula. Results: A total of 134 patients were included in the study. The prevalence of positive fundus finding and macular OCT finding was 35% (95% confidence interval [CI]: 27%, 43%) and 13% (95% CI: 8%, 19%), respectively; 62 eyes of 47 patients had positive fundus findings, whereas 30 eyes of 18 patients had positive macular OCT findings. Scotoma (p < 0.001), near vision disturbance (p = 0.04), and abnormal Amsler findings (p < 0.001) were significantly associated with presence of macular OCT findings compared to absence of macular OCT findings. In the total of 268 eyes, the two most common fundus findings were vessel tortuosity (53 [20%]) and yellow subretinal dot (28 [10%]). Out of 30 eyes, diffuse retinal thickening was the most frequent OCT finding (22 [73%]), followed by 4 (13%) with foveolitis, 3 (10%) with cystoid macular oedema and 1 (3%) with submacular fluid. Platelet count and haematocrit were not associated with abnormal fundus or macular OCT manifestation in patients suffering from dengue fever. Conclusion: Our study revealed that the prevalence of clinical fundus and macular OCT findings among dengue inpatients was higher when compared to other countries, especially during dengue outbreaks. Furthermore, the spectrum of fundus and macular OCT findings in our population can be varied.

Headache can be a primary or secondary disorder. The characteristics of headache and its associated features, especially the presence of red flag signs, are important in distinguishing secondary from primary causes. Hemicrania continua is a type of primary headache disorder characterized by a continuous unilateral headache with episodes of exacerbations and association with cranial autonomic symptoms, which include several ocular symptoms. The absolute response to indomethacin remains the hallmark of this disease. We would like to report a rare case of hemicrania continua with scintillating scotoma during exacerbations apart from the typical autonomic features of conjunctival injection, ptosis, eyelid edema, and lacrimation.

Anaerobic digestion has been widely employed in waste treatment for its ability to capture methane gas released as a product during the digestion. Certain wastes, however, cannot be easily digested due to their low nutrient level insufficient for anaerobic digestion, thus co-digestion is a viable option. Numerous studies have shown that using co-substrates in anaerobic digestion systems improve methane yields as positive synergisms are established in the digestion medium, and the supply of missing nutrients are introduced by the co-substrates. Nevertheless, large-scale implementation of co-digestion technology is limited by inherent process limitations and operational concerns. This review summarizes the results from numerous laboratory, pilot, and full-scale anaerobic co-digestion (ACD) studies of wastewater sludge with the co-substrates of organic fraction of municipal solid waste, food waste, crude glycerol, agricultural waste, and fat, oil and grease. The critical factors that influence the ACD operation are also discussed. The ultimate aim of this review is to identify the best potential co-substrate for wastewater sludge anaerobic co-digestion and provide a recommendation for future reference. By adding co-substrates, a gain ranging from 13 to 176% in the methane yield was accomplished compared to the mono-digestions.

This paper reports a techno-economic assessment for industrial scale bio-flocculant production with okra as biomass feedstock. The sludge dewatering ability of the bio-flocculant was evaluated prior to economic analysis. Several optimisation strategies were investigated in order to lower the bio-flocculant production cost. The results showed that continuous mode microwave extraction was more economically beneficial than conventional extraction in batch and continuous modes. Sensitivity analysis revealed that the production cost was significantly affected by annual production and extract yield, and moderately influenced by raw material price. The optimised scheme for bio-flocculant production was continuous mode microwave extraction at 90° C, a residence time of 10 minutes, a water loading of 3.5 w/w and production rate of 220 tonnes per year. The economic assessment showed that the gross margin was positive, return on investment was in the expected range of 20 to 30% and payback time was within 5 years.

Three main parameters of palm oil mill effluent (POME) i.e. biological oxygen demand (BOD), total suspended solids (TSS) and oil and grease (O&G), at high concentrations, have hindered efficient anaerobic digestion (AD) due to sludge flotation and scum formation. In this study, Moringa Oleifera extract was co-digested with POME to allow TSS and O&G to be coagulated and settled, and hence, an immobilisation media formed for better digestibility. Mono-digestion (POME, T1 and M. oleifera extract, T2, separately) served as control while co-digestion involved dosing 50 mL of M. oleifera extract (500 mg/L) into a fixed volume of POME (450 mL) at two feeding modes: daily, day 1 to day 30 (T3) and one-time, day 1 (T4). Treatments T1-T4 were conducted in an enclosed AD system for 30 days and the undesirable organic materials removal efficiencies i.e. BODremoval, TSSremoval and O&Gremoval were compared. POME co-digestion, T4, showed an improved 92% TSSremoval, 94% BODremoval and methane yield of 24.3 mL CH4/g COD removed. The results suggested that the nitrogen-fixing capabilities of anoxic microbial cells enhanced proliferation and growth encapsulated within the immobilisation media. Methanogen bacterial DNAs isolated from POME, granular sludge and anaerobically-treated POME were identified as Methanoculleus spp., Methanolinea spp. and Methanoculleus spp., respectively. Two-step complementary DNA (cDNA) and quantitative polymerase chain reaction (qPCR) confirmed the highest methanogen DNA concentration in T4. Therefore, the naturally occurring underutilised M. oleifera can be an organic coagulant for efficient POME co-digestion with an overall 69% and 59.5% higher methane yield and TSSremoval than mono-digestion.

Central serous chorioretinopathy (CSCR) is a retinal condition characterized by fluid accumulation in the subretinal space, resulting in neurosensory detachment or pigment epithelial detachment. The risk factors associated with this condition include male gender, middle age, smoking, stress and use of corticosteroids. We report a case of CSCR in a 37-year-old policeman with hypertension and bronchial asthma. He presented with sudden onset of bilateral blurring of central vision for 1 day, worse over the left eye. There were no other significant eye complaints. He is an active smoker and has been on long-term corticosteroids for asthma. On examination, the visual acuity was 6/9 bilaterally. The anterior segment of both eyes was normal. Examination of the right fundus revealed a dome-shaped swelling inferior to the fovea, while the left fundus showed circular detachment of the neurosensory retina at the macula. He was diagnosed to have bilateral central serous chorioretinopathy. He was also counseled to stop smoking. The corticosteroids were continued due to the risk of precipitating an asthma attack if they were withheld. Upon his next review two months later, his condition remained stable. CSCR is usually a self-limited condition, with good visual outcome. A thorough medical, social and drug history should be obtained, and patients advised to modify their lifestyle to eliminate or reduce risk factors such as smoking, stress and corticosteroid use.

We report a case series of dengue maculopathy with different ocular manifestations, managements, visual outcomes and sequelae of patients. All three cases were diagnosed to have dengue fever. Patients presented with symptoms of central scotoma (case 1 and case 3) and blurring of vision (case 2) on Day 9 of dengue fever. Fundus examination showed intra retinal haemorrhages (case 1 and case 2) and macula thickening (case 3). Optical coherence tomography (OCT) revealed macular thickening with intra retinal fluid (case 1) and diffuse retinal thickening (case 3), while in case 2, it had irregular ellipsoid line in OCT. Fundus fluorescence angiography (FFA) revealed parafoveal vasculitis. After treatment with systemic steroids, one patient had good visual outcome (case 2), while two others had a persistent central scotoma due to macula atrophy (case 3). Although it is a self limiting disease, but the mode of treatment is variable. Treatment with corticosteroids may hasten recovery of vision and prevent permanent visual impairment.

Palm oil mill effluent has been extensively researched via three different technologies, namely chemical, physicochemical and biological treatment methods. Biological treatment by anaerobic and aerobic means is currently the most commonly used method for palm oil mill effluent. However, the greatest challenge posed by them is the inconsistent biological oxygen demand of 20 mg/L for the final treated effluent. Large amount of investment for additional polishing plant prior to the final discharge has been utilised intentionally to further reduce the biochemical oxygen demand values, but the problem remains unresolved. The performance of current palm oil mill effluent treatment system deployed by the industry was evaluated by comparing two different types of anaerobic treatments: open ponding and covered lagoon systems (with hydraulic and gas mixing). The covered lagoon with hydraulic mixing achieved the highest chemical oxygen demand, total suspended solids, total volatile solids and lignin removal efficiencies of >80% compared to other systems which showed

Yoga has recently been touted as a means to improve physical and mental well-being. However, no form of exercise is without its risks. A 32-year-old Chinese female with moderate myopia complained of right eye sudden onset of floaters and mild blurring of vision after the head-down posture. The visual acuity was 6/12 in the right eye and 6/9 in the left eye. A right eye fundus examination showed posterior vitreous detachment, with a small blood clot located at the inferior margin of the optic disc. The patient was diagnosed with right eye vitreous hemorrhage secondary to acute posterior vitreous detachment and was managed conservatively. Acute changes in posture, especially between an upright and a head-down position, may cause acute posterior vitreous detachment. As yoga practitioners may be required to assume this head-down position, myopic patients should be warned of the possible ocular complications of this exercise.

The production of natural biopolymers as flocculants for water treatment is highly desirable due to their inherent low toxicity and low environmental footprint. In this study, bio-flocculants were extracted from Hibiscus/Abelmoschus esculentus (okra) by using a water extraction method, and the extract yield and its performance in sludge dewatering were evaluated. Single factor experimental design was employed to obtain the optimum conditions for extraction temperature (25–90 °C), time (0.25–5 h), solvent loading (0.5–5 w/w) and agitation speed (0–225 rpm). Results showed that extraction yield was affected non-linearly by all experimental variables, whilst the sludge dewatering ability was only influenced by the temperature of the extraction process. The optimum extraction conditions were obtained at 70 °C, 2 h, solvent loading of 2.5 w/w and agitation at 200 rpm. Under the optimal conditions, the extract yield was 2.38%, which is comparable to the extraction of other polysaccharides (0.69–3.66%). The bio-flocculants displayed >98% removal of suspended solids and 68% water recovery during sludge dewatering, and were shown to be comparable with commercial polyacrylamide flocculants. This work shows that bio-flocculants could offer a feasible alternative to synthetic flocculants for water treatment and sludge dewatering applications, and can be extracted using only water as a solvent, minimising the environmental footprint of the extraction process.

Upflow anaerobic sludge blanket-hollow centered packed bed (UASB-HCPB) reactor was developed with the aim to minimize operational problems in the anaerobic treatment of Palm Oil Mill Effluent (POME) under thermophilic conditions. The performance of UASB-HCPB reactor on POME treatment was investigated at 55 °C. Subsequent to start-up, the performance of the UASB-HCPB reactor was evaluated in terms of i) effect of hydraulic retention time (HRT); ii) effect of organic loading rate (OLR); and iii) effect of mixed liquor volatile suspended solid (MLVSS) concentration on thermophilic POME treatment. Start-up up of the UASB-HCPB reactor was completed in 36 days, removing 88% COD and 90% BOD respectively at an OLR of 28.12 g L−1 d−1, producing biogas with 52% of methane. Results from the performance study of the UASB-HCPB reactor on thermophilic POME treatment indicated that HRT of 2 days, OLR of 27.65 g L−1 d−1 and MLVSS concentration of 14.7 g L−1 was required to remove 90% of COD and BOD, 80% of suspended solid and at the same time produce 60% of methane.

Palm Oil Mill Effluent (POME) treatment has always been a topic of research in Malaysia. This effluent that is extremely rich in organic content needs to be properly treated to minimize environmental hazards before it is released into watercourses. The main aim of this work is to evaluate the potential of applying natural, chemically and thermally modified banana peel as sorbent for the treatment of biologically treated POME. Characteristics of these sorbents were analyzed with BET surface area and SEM. Batch adsorption studies were carried out to remove color, total suspended solids (TSS), chemical oxygen demand (COD), tannin and lignin, and biological oxygen demand (BOD) onto natural banana peel (NBP), methylated banana peel (MBP), and banana peel activated carbon (BPAC) respectively. The variables of pH, adsorbent dosage, and contact time were investigated in this study. Maximum percentage removal of color, TSS, COD, BOD, and tannin and lignin (95.96%, 100%, 100%, 97.41%, and 76.74% respectively) on BPAC were obtained at optimized pH of 2, contact time of 30 h and adsorbent dosage of 30 g/100 ml. The isotherm data were well described by the Redlich-Peterson isotherm model with correlation coefficient of more than 0.99. Kinetic of adsorption was examined by Langergren pseudo first order, pseudo second order, and second order. The pseudo second order was identified to be the governing mechanism with high correlation coefficient of more than 0.99.

Transesterification of oils/triglycerides (TGs) with alcohol in the presence of catalyst has been the most commonly used process to produce biodiesel. Major limiting factors of conventional biodiesel transesterification process are phase separation and product purification. Precise and correct knowledge of the phase equilibrium behaviour is crucial for future industrial biodiesel reaction, separation and purification processes. For this purpose, it is important to consider the phase equilibrium behaviour in order to thoroughly understand the entire transesterification system for biodiesel production, which consists of six components. This work is to discuss on the liquid–liquid equilibrium (LLE) data of six-component system which involves TG, palm biodiesel (FAME), methanol (MeOH), glycerine (GLY), diglyceride (DG) and monoglyceride (MG). The phase equilibrium data of this system were determined experimentally through transesterification of crude palm oil (CPO). The experimental LLE data have been transposed into a pseudo-ternary diagram as TG–DG–MG + MeOH–GLY + FAME for better visualisation and understanding of the six-component system. Results showed that the transesterification of TG to FAME has formed a two-phase system where CPO-rich phase and MeOH-rich phase co-existed during the reaction. Due to immiscibility of CPO and MeOH, as well as the miscibility of FAME and MeOH, the LLE data suggested that at specific reaction operating condition, the reacted product (FAME) could be continuously removed by separating the MeOH phase from the CPO phase. This favours the forward transesterification reaction and eventually enhances the reaction efficiency to produce an oil-free FAME.

Anaerobic systems operated under thermophilic condition often encounter longer start-up period and operating problems pertaining to temperature shift when mesophilic seed sludge were utilized as thermophilic sludge. Bioaugmentation products for thermophilic conditions were not readily available in the market. Hence, a thermophilic mixed culture has been cultivated specifically for Palm Oil Mill Effluent (POME) treatment at thermophilic conditions using a batch Continuous Stirred Tank Reactor (CSTR) where POME was utilized as a substrate for the growth of microbes. The thermophilic mixed culture managed to reduce at least 90% of Chemical Oxygen Demand (COD) in POME with a hydraulic retention time (HRT) of 6 days with a MLSS concentration of 14,000 mg/L. The biogas produced from the batch CSTR contained at least 64% of methane. The kinetic parameters for batch thermophilic POME treatment were obtained by fitting the Chen and Hashimoto's model to the experimental data. The maximum substrate utilization rate for this system was found to be 0.476 day −1 , which was higher than the systems operated under mesophilic range, and dimensionless kinetic parameters k and Q were −1.365 and 0.0007 respectively. The mixed culture had a methanogenic population which consisted of Methanosaeta thermophila , Methanosarcina thermophila , Methanobacterium thermoautotrophicum , Methanobacterium thermoformicicum and Methanobacterium wolfei .

The production of highly polluting palm oil mill effluent (POME) has resulted in serious environmental hazards. While anaerobic digestion is widely accepted as an effective method for the treatment of POME, anaerobic treatment of POME alone has difficulty meeting discharge limits due to the high organic strength of POME. Hence, subsequent post-treatment following aerobic treatment is vital to meet the discharge limits. The objective of the present study is to investigate the aerobic treatment of anaerobically digested POME by using a sequencing batch reactor (SBR). The SBR performance was assessed by measuring Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS) removal as well as Sludge Volume Index (SVI). The operating pH and dissolved oxygen concentrations were found to be 8.25-9.14 and 1.5-6.4 mg/L, respectively, throughout the experiment. The experimental results demonstrate that MLVSS, OLR and sludge loading rate (SLR) play a significant role in the organic removal efficiency of SBR systems and therefore, further investigation on these parameters was conducted to attain optimum SBR performance. Maximum COD (95-96%), BOD (97-98%) and TSS (98-99%) removal efficiencies were achieved at optimum OLR, SLR and MLVSS concentration ranges of 1.8-4.2 kg COD/m(3)day, 2.5-4.6 kg TSS/m(3)day and 22,000-25,000 mg/L, respectively. The effluent quality remained stable and complied with the discharge limit. At the same time, the sludge showed good settling properties with average SVI of 65. It is envisaged that the SBR process could complement the anaerobic treatment to produce final treated effluent which meets the discharge limit.

Non-arteritic anterior ischaemic optic neuropathy (NAION) may develop due to severe anaemia and hypotension which is seen in acute blood loss. The devastating visual loss is often irreversible. We report a case of NAION in a 20-year-old healthy woman, who presented on the third day of a heavy menstrual cycle with hypovolaemic shock. On day 2 of admission, she had sudden right eye blurring of vision at the superior field on awakening from sleep. Funduscopy revealed a pale and swollen right optic disc. There was a dense right superior altitudinal visual field defect. Her haemoglobin level was low (3.6 g/dL), but she refused blood transfusion due to her religious belief (Jehovah's Witness) and opted for conservative management. She later developed right optic atrophy with persistent visual field defect despite an improved haemoglobin level of 10.5 g/dL.

The present study is intended for the first time to completely replace the inorganic coagulants with organic polymers in palm oil mill effluent (POME) pretreatment by using direct flocculation of single and dual polymer systems under applied shear. The efficiency of direct flocculation of POME was investigated by using the Population Balance Model (PBM) which considered the charge neutralization and bridging attraction under applied shear. The collision efficiency was calculated based on the Derjaguin Landau Verwey Overbeek (DLVO) theory which considered the effect of adsorbed polymer layers on van der Waals attraction and bridging attraction. This is the first attempt to correlate the floc size distribution from PBM to the indirect indicators of COD, suspended solids, oil and grease. The model predictions are in close agreement with the experimental results for both single and dual polymer systems. The interaction energy curves based on PBM shows that the flocculation using cationic polymer is by charge neutralization and bridging attraction whereas flocculation using anionic polymer is by only bridging attraction. At the optimum flocculation conditions, 99.66%, 55.79%, 99.74% and 80.78% of suspended solids, COD, oil and grease removal and water recovery are achieved, respectively. The direct flocculation process significantly reduced the treatment cost by a factor of 3.6 compared to the conventional coagulation–flocculation process.

A mathematical model suitable for the multiple solutes system in continuous cross-flow ultrafiltration is developed. This model is based on mass balance analysis coupled with the filtration theory (osmotic pressure model, Kozeny–Carman equation), resistance-in-series model and gel polarization model. This model is characterized by the parameters R m , P m , K b , K bi and k i . These parameters are estimated by using the Levenberg–Marquardt method coupled with the Gauss–Newton algorithm based on the experimental data obtained from the treatment of pretreated palm oil mill effluent (POME) as a feed in the pilot plant scale ultrafiltration system. The pretreated POME is composed of a ternary system with the solutes of carbohydrate constituents, crude protein and ammoniacal nitrogen. The simulation results show a good agreement with the experimental data. The proposed model is suitable for predicting the performance of multiple solutes in an ultrafiltration process. The concentration of each solute present is correlated with the COD value of the permeate stream.

Flocculation is extensively employed for clarification through sedimentation. Application of eco-friendly plant-based bioflocculants in wastewater treatment has attracted significant attention lately with high removal capability in terms of solids, turbidity, color, and dye. However, moderate flocculating property and short shelf life restrict their development. To enhance the flocculating ability, natural polysaccharides derived from plants are chemically modified by inclusion of synthetic, nonbiodegradable monomers (e.g., acrylamide) onto their backbone to produce grafted bioflocculants. This review is aimed to provide an overview of the development and flocculating efficiencies of plant-based bioflocculants and grafted bioflocculants for the first time. Furthermore, the processing methods, flocculation mechanism, and the current challenges are discussed. All the reported studies about plant-derived bioflocculants are conducted under lab-scale conditions in wastewater treatment. Hence, the possibility to apply natural bioflocculants in food and beverage, mineral, paper and pulp, and oleo-chemical and biodiesel industries is discussed and evaluated.

A one-dimensional model for the multiple solutes filtration system is developed by extending the Spiegler–Kedem model by incorporating the solute–solute interactions. This extended Spiegler–Kedem model is suitable for predicting the performance of multiple solutes system in nanofiltration. The model is characterized by the parameters of Lp, σs, Psi, Pss and ks. The parameters were estimated using the Levenberg–Marquardt method coupled with Gauss–Newton algorithm based on the experimental data obtained from the literature. The simulation results obtained from the proposed model were also compared with the simulation results obtained from the Spiegler–Kedem model and extended Nerst–Plank model, respectively. The simulation results indicate that the flux behavior and the predicted permeate concentrations were in good agreement with that predicted by the two existing models and the experimental data. The extended Spiegler–Kedem model developed is suitable for predicting the performance of multiple solutes for nanofiltration system.

Thermophilic treatment of palm oil mill effluent (POME) was studied in a novel integrated anaerobic-aerobic bioreactor (IAAB). The IAAB was subjected to a program of steady-state operation over a range of organic loading rate (OLR)s, up to 30 g COD/L day in order to evaluate its treatment capacity. The thermophilic IAAB achieved high chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) removal efficiencies of more than 99% for OLR up to 18.5 g COD/L day. High methane yield of 0.32 LCH(4) (STP)/g COD(removed) with compliance of the final treated effluent to the discharge limit were achieved. This is higher than that of the mesophilic system due to the higher maximum specific growth rate (μ(max)) of the thermophilic microorganisms. Besides, coupling the model of Grau second order model (anaerobic system) with the model of Monod (aerobic system) will completely define the IAAB system.

Natural bio-flocculants were extracted from okra and Chinese yam using water extraction method, and the extract yield and their flocculating abilities were evaluated. Results showed that extraction of okra with seed removal and incubation followed by freeze drying enhanced the extract yield by 91% and improved the flocculating ability greatly by achieving solids removal of above 99% when compared with extraction without incubation and followed by oven drying. The effect of an incubation step was further investigated by using Chinese yam. With incubation, a higher extract yield of 2.95% was obtained compared with the extraction without incubation at 2.13% and high flocculating ability was achieved at 99.5% solids removal. To further investigate the application of bio-flocculants, the samples with the highest extract yield and flocculating ability were selected for a case study focusing on treatment of oleochemical wastewater. Yam bio-flocculant showed its flocculating activity with 80% solids removal when it was coupled with coagulant without pH alteration. However, pH adjustment was required for okra bio-flocculant. In conclusion, highly efficient okra and yam bio-flocculants were successfully extracted and their applicability to wastewater treatment was proven.