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Bio-cementation is a new sustainable approach that has gained popularity due to its low energy and carbon dioxide footprint compared with those of existing technologies for geotechnical and geoenvironmental engineering applications. Bio-cementation is a soil improvement technique that involves binding the pore space of soil particles with calcium carbonate minerals by microbially induced carbonate precipitation (MICP) and filling the soil pore space. The purpose of this paper is to present the current state of the art and a comprehensive discussion on the development of bio-cementation for soil improvement/reinforcement. Premixing, injection, immersing and surface percolation are identified as four distinct bio-cementation treatment techniques. Furthermore, scholars have reported employing ureolytic bacteria such as Sporosarcina pasteurii, Bacillus sphaericus and Lysinibacillus sphaericus isolated from corals, limestone caves, soils, waste materials, seawater and other sources to accomplish effective bio-cementation. Some of the major issues (bacterial cultivation costs and ammonium production) that impede its industrial potential and promising remedial techniques are also discussed. This state-of-the-art review also discusses the benefits and drawbacks of bio-cementation compared with traditional approaches. The significance of enzyme-induced carbonate precipitation as a soil bio-cementation alternative to MICP is also highlighted. Finally, the sustainable procedure, bio-cementation principles and future implications are discussed.

The process of ureolysis-driven biocementation is used to improve granular soils. The precipitation of calcium carbonate (CaCO3) crystals results from the reactions of urease generated by ureolytic bacteria and chemical reagents, which strengthen or bind soil particles together. Using a lab-based scaled physical model, this study investigated the influence of selected spacing intervals (107, 214 and 321 mm) on the effectiveness of biocementation through the injection–suction or ‘push–pull’ approach. Polystyrene moulds were used to create soil specimens. These were then injected with six cycles of treatment solutions at the intervals stated. The compressive strengths and calcium carbonate contents of the biocemented soil specimens were measured after curing. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy and effluent analysis (pH and ammonium measurements) were also performed. The biocemented soil specimens with different spacing intervals obtained compressive strengths of 2.53 ± 1.06 to 4.2 ± 2.3 MPa, while the calcium carbonate contents were from 2.78 ± 0.3 to 11.16 ± 1.5%. The elemental compositions and bonding of calcium carbonate precipitates in the biocemented soil were confirmed by EDS and FTIR spectra, while SEM micrographs revealed chip-like and irregular rhombohedral crystal forms. The results demonstrated that injection spacing had an effect on biocemented soil treated by microbially induced carbonate precipitation.

Understanding the degradation rate of polyethylene (PE) plastic mediated by bacterial-fungal consortium (BFC) is important to ensure an effective design process of bioremediation technology. This study aims to investigate the degradation behavior of PE plastic waste mediated by the BFC colonies using the modified mass transfer factor models to get better understanding on the kinetics and mechanisms of internal, external and global mass transfer. The performance of rectangular reactor (RR) to degrade PE plastic reaching 61.5% of the efficiency shows an increased efficiency of 55.9% stimulated by the presence of BFC strains in the breakdown of complex PE molecules during the process of bioremediation. Trend in the variation of [kLa]d value viewed almost the same with that of [kLa]g value is higher than that of [kLa]f value during 150 days of the experiment hence the rate-limiting step of PE plastic waste degraded depends on the resistance of external mass transfer. Analysis of degradation efficiency pursuant to both the factors of internal and external mass transfer during the 150-day experimental period provides a new insight on the role of BFC strains to increase the performance of RR process contributing to advance the future bioremediation process of PE plastic waste.

This paper presents a study on household waste management and recycling awareness. Residential areas are the major sources of solid waste as that is where people live. The waste that is usually disposed of from residential areas includes food waste, plastic waste, paper, glass, tin, and others. The increasing trend in waste generated from homes has become a major concern. This study aimed to assess household waste management and recycling awareness in two residential areas located in Padang Terap District, Kuala Nerang, Kedah, Malaysia. Recently, Padang Terap district showed an increase in waste generated compared to another district, Kedah. An open-ended questionnaire was distributed to approximately 32 respondents, and an interview was conducted to study household waste management and recycling awareness in two residential areas—Taman Jati and Taman Pelangi. The research shows that household waste management to segregate the waste remains a problem, despite most respondents being aware of this issue through different media. Furthermore, the lack of household waste management and recycling programs and facilities by the local authorities caused residents to be reluctant to practice these activities.

The century of urbanisation and industrialisation had a great impact on the environment due to the rapid growth of the flue gas sectors. Thus, green technology is enforced to convert carbon dioxide (CO2) gas into methane (CH4) gas as an alternative fuel in electricity generation, particularly coal and natural gas sources. Cerium (Ce) was recognised as one of the most basic and unique redox characteristics utilised in the promising methanation reaction among catalysts used. The trimetallic catalyst used in this work was prepared with Ce as the based catalyst and ruthenium/magnesium (Ru/Mg) as the impregnated metal. Response surface methodology projected the CO2 conversion to be less than 0.3% of the experimental value of 78.82% using the indicated parameters of 593 °C calcination temperature and 61 wt.% ratios. Ru/Mg/Ce/Al2O3 catalyst with 60 wt.% of Ce loading calcined at 600 °C produced 58.08% of CH4. The characterisation results revealed that CeO2, Mg(Al2O4), and RuO2 species were the active species for CO2 methanation selectivity, as observed in XRD and XPS analyses. The mesoporous structure and particle agglomeration resulted in a surface area of 147 m2/g.

The smaller particles that dominate the particle number concentration (PNC) in the ambient air only contribute to a small percentage of particulate matter (PM) mass concentration although present in high particle number concentration. These small particles may be neglected upon assessing the health impacts of the PM. Hence, the knowledge on the particle number concentration size distribution deserves greater attention than the particulate mass concentration. This study investigates the measurement of the particle mass concentrations (PM2.5) and PNC of 0.27 μm

Microbially induced carbonate precipitation (MICP) is a remarkable method that creates sustainable cementitious binding material for use in geotechnical/structural engineering and environmental engineering. This is due to the increasing demand for alternative environmentally friendly technologies and materials that result in minimal or zero carbon footprint. In contrast to the previously published literature, through bibliometric analysis, this review paper focuses on the current prospects and future research trends of MICP technology via the Scopus database and VOSviewer analysis. The objective of the study was to determine the annual publications and citations trend, most contributing countries, the leading journals, prolific authors, productive institutions, funding sponsors, trending author keywords, and research directions of MICP. There were a total of 1058 articles published from 2001 to 2021 on MICP. The result demonstrated that the volume of publications is increasing. China, Construction and Building Materials, Satoru Kawasaki, Nanyang Technological University, and the National Natural Science Foundation of China are the leading country, journal, author, institution, and funding sponsor in terms of total publications. Through the co-occurrence analysis of the author keywords, MICP was revealed to be the most frequently used author keyword with 121 occurrences, a total link strength of 213, and 152 links to other author keywords. Furthermore, co-occurrence analysis of text data revealed that researchers are concentrating on four important research areas: precipitation, MICP, compressive strength, and biomineralization. This review can provide information to researchers that can lead to novel ideas and research collaboration or engagement on MICP technology.

Air pollution is a crucial contributor to premature mortality and health problems. The excessive inhalation of fine particulate matter (PM2.5) is strongly associated with adverse health effects due to its capability to penetrate deep into the human respiratory system. This study aimed to analyze the seasonal cycles of 24 h average PM2.5 mass concentrations in a suburban area in the southern region of Peninsular Malaysia. The meteorological variables and PM2.5 data were obtained via a Grimm Environmental Dust Monitor from August 2017 until January 2018. The maximum 24 h mass concentration was 44.6 µg m–3, with a mean value of 21.85 µg m–3, which was observed during the southwest monsoon . 43.33% and 8.33% of the daily concentrations exceeded the 24 h World Health Organization Guideline and Malaysian Ambient Air Quality Standard, respectively. The variation in the PM2.5 mass ranged between 0.53 and 0.90 times of the PM10 mass, indicating that the PM2.5 consistently contributed 52–92% of the PM10 mass concentration. During the monsoon seasons, the ambient temperature exhibited a significant positive correlation (p < 0.05) with the PM2.5 mass concentration (r = 0.425–0.541), whereas the wind speed (r = –0.23 to –0.0127) and the relative humidity (r = –0.472 to –0.271) displayed strong negative correlations with it. Additionally, the rainfall was weakly correlated with the mass concentration. The presence of northeasterly wind at the study site suggests that the PM2.5 originated from sources to the northeast, which are influenced by anthropogenic activities and high traffic.

Air pollution is a worldwide issue that is mainly caused from excessive inhalation of hazardous PM2.5 pollutant that is emitted into the air. The objective of this study is to assess the fundamental knowledge revolving PM2.5 (particles aerodynamic diameter of lower than or equal to 2.5 μm) and its inorganic composition in ambient air of urban areas, mainly in Malaysia in comparison to other Southeast Asia countries. This research also investigates the theory of particle number concentration (PNC) with PM2.5, also the health effects and origins of the emissions. The factors affecting the PM2.5 mass include the local emission, El Nino phenomenon, land, meteorological effects, monsoons, rainfall events, sea breeze, transboundary pollution and seasonal changes. 24 h mean PM2.5 mass concentration for metropolitan regions in the SEA is in the range of 11 μgm−3 and 72.3 μgm−3, while between 5.30 μgm−3 and 55.89 μgm−3 for semi-urban zones. For rural area, the 24 h mean PM2.5 value is about 30 μgm−3. The findings indicate that metals in PM2.5 emission are frequently Pb, Se, Zn, Cd, As, Bi, Ba, Cu, Rb, V, Ni, Fe, Ca, Mn, Cr, Al, Si and K, where Zn has the uppermost range of 133.50 to 419.30 ngm−3 while the major water-soluble ions exist are NH4+, K+, Ca2+, Na+, in which Na+, NH4+ and Cl- are present in aged sea salt and mixed industrial, Ca2+ and Mg2+ present in mineral dust, NH4+, K+ and SO42− present in mixture of SIA and biomass burning. There is a high correlation between the particle mass concentration and PNC level, especially the ones in accumulation mode (PNC0.1–1.0) which are mostly originated from the emission of heavy traffic streets.

The smaller particles that dominate the particle number concentration (PNC) in the ambient air only contribute to a small percentage of particulate matter (PM) mass concentration although present in high particle number concentration. These small particles may be neglected upon assessing the health impacts of the PM. Hence, the knowledge on the particle number concentration size distribution deserves greater attention than the particulate mass concentration. This study investigates the measurement of the particle mass concentrations (PM

The aim of the present study is to investigate the potential of magnetic field application as an alternative approach for controlling sludge bulking due to long sludge retention time (SRT) while enhancing nitrification efficiency upon the occurrence. Two sequencing batch reactors, reactor A (SBR(A), magnetic field intensity 88.0 mT) and reactor B (SBR(B), control) were operated under long SRT to induce the growth of filamentous microorganisms. The effect of magnetic field on nitrification, viz. ammonia–nitrogen (NH(4)–N) and nitrite removal, as well as biomass properties were studied under the sludge bulking condition. Results indicated that nitrification efficiency of SBR(A) was consistently higher with 90% NH(4)–N removal and 74–81% nitrite removal, which could be credited to the enhanced biomass properties of activated sludge due to the induced magnetic field. Metabolism activity and biodegradability of aerobic bacteria were also enhanced through the application of magnetic field, even under long SRT condition. This was evidenced by the average oxygen uptake rate (OUR) in SBR(A) that was higher with 11.7 ± 1.2 mg/L·h compared to SBR(B) with 9.5 ± 0.4 mg/L·h. Occurrence of filamentous sludge bulking was likewise minimized.

The present work investigates the feasibility of aerobic granulation for the treatment of low-medium strength domestic wastewater for long-term operation and effects of a static mixer on the properties and removal performances of the aerobic granules formed. The static mixer was installed in a sequential batch reactor to provide higher hydrodynamic shear force in enhancing the formation of the aerobic granules. Aerobic granules were successfully formed in the domestic wastewater, and the granulation treatment system was sustained for a period of 356 days without granules disintegration. Subsequent to the installation, aerobic granules with a low SVI30 of 41.37 mL/gTSS, average diameter 1.11 mm, granular strength with integrity coefficient 10.4% and regular shape with minimum filamentous outgrowth were formed. Mineral concentrations such as Fe, Mg, Ca and Na as well as composition of protein and polysaccharide in tightly bound-extracellular polymeric substance of the aerobic granules were found to be higher under the effect of the static mixer. However, no significant improvement was observed on the TCOD, NH4+-N and TSS removal performance. Good TCOD and TSS removal performance of above 85% and 90%, respectively and moderate NH4+-N removal performance of about 60% were observed throughout the study. Higher simultaneous nitrification and denitrification (SND) efficiency of 56% was observed after the installation of the static mixer, as compared to 21% prior. Therefore, it may be concluded that the installation of the static mixer significantly improved the properties of aerobic granules formation and SND efficiency but not the TCOD, NH4+-N and TSS removal performance.

Nutrients contribute to the wellbeing of water bodies. However, excessive enrichment of water bodies by nutrients could harm aquatic organisms. Some of the severe environmental problems caused by nutrients on water bodies include eutrophication and algal bloom. In children, consumption of nitrate-polluted water causes methaemoglobinemia. Consumption of food irrigated with nutrient-polluted wastewater has been associated with several health implications. These nutrients primarily originate from point and non-point sources. Several biological-suspended treatment systems have been developed to reduce nutrients to acceptable limits prior to discharge into water bodies. These treatment systems are associated with several merits and demerits. This chapter explores the implications of water body enrichment by nutrients and their impact on health, economy, and environment. Furthermore, some suspended growth treatment systems applied for the treatment of nutrient polluted wastewater were explored.

The current work aimed to investigate the removal mechanism of NH4+ from wastewater treatment plant effluent (WWTPE) onto the zeolite in the plug-flow column reactor (PFCR). The adsorption process was optimised as a function of length (2–15), time (0.5–202 min), and accumulation (0.05–2.4 mg/g) using response surface methodology (RSM). The optimal operating parameters for the adsorption were recorded after 134.89 min with 1.52 mg/L of zeolite with 6.685 cm of the column length where the predicted and actual removal was 99.79 vs. 98.00% of NH4+ from WWTPE. The bed depth service time (BDST), Thomas, and Yoon-Nelson models were used to explain the adsorption behaviour. In contrast, the mass transfer factor (MTF) model was carried out to determine the internal and external removal mechanism. The findings revealed that PFCR exhibited an efficiency for removing NH4+ from WWTPE. The dynamic adsorption behaviour was satisfactorily described by the BDST, Thomas, and Yoon-Nelson models. These findings confirmed that the empirical models had verified the suitable of PFCR for removing NH4+ from WWTPE.

Electrocoagulation has emerged a reliable technology for the treatment of various wastewaters. Its basic principle depends on the response of water particles to strong electric field in a redox reaction. Oxidation of the anode material releases coagulating agents that form metal hydroxide complexes which neutralize particulate materials to form agglomerates. The agglomerates either settle at the bottom or float to the surface depending on the removal path of the electrocoagulation reactor. The merits of electrocoagulation include minimal sludge generation, minimal operator attention, simple equipment, high pollutant removal capacity, and ease of operation. Therefore, this chapter explores the mechanisms of electrocoagulation, components of electrocoagulation, benefits, and demerits of electrocoagulation. Furthermore, the similarity between electrocoagulation and coagulation is explored. Application of electrocoagulation for the treatment of various wastewaters was explored. Feasibility of electrocoagulation was examined through cost evaluation with other treatment technologies.

Extra-cellular polymeric substances are responsible towards bioflocculation and settleability of sludge. This substances act as glue that holds the bioflocs to form larger aggregates by intervening both cells cohesion and adhesion. Different composition of this substances lead to different circumstances of sludge problem including bulking. Numerous studies have been conducted in optimizing the content of extra-cellular polymeric substances using various approaches. However, none of the approaches investigated on the use of magnetic field. Therefore, this study is aimed to investigate the effect of magnetic field on extra-cellular polymeric substances specifically its soluble-bound composition and its chemical constituents. Magnetic field of 88 mT was used in Reactor A, while Reactor B acted as control system. Results showed that Reactor A obtained mostly higher tightly bound extra-cellular polymeric substances compared to Reactor B in order of predominance: protein > polysaccharides > carbohydrates. These observations implied that magnetic field influenced the production of polymeric substances mainly its tightly bound constituent as well as protein and polysaccharides content. These productions were significant in improving bioflocculation and sludge settleability, thus minimizing potential occurrence of bulking.

In this preliminary study, a natural flocculant is developed from an oil palm trunk. The flocculant further tested for its ability in turbidity and COD removal with additional of atrazine in wastewater and demineralised water matrix. At the optimum dosage of 20mg/L, the developed cationic OPT starch able to remove around 95% turbidity and 85% COD. In addition, the cationic OPT starch also show the ability to remove spiked atrazine from both water matrixes to the maximum range of 55-85%. In conclusion, the developed oil-palm based flocculant show great potential for real-world application with added cost-effective benefits.

Understanding of mass transfer kinetics is important for biosorption of nitrogen compounds from palm oil mill effluent (POME) to gain a mechanistic insight into future biological processes for the treatment of high organic loading wastewater. In this study, the rates of global and sequential mass transfer were determined using the modified mass transfer factor equations for the experiments to remove nitrogen by aerobic granular sludge accumulation in a sequencing batch reactor (SBR). The maximum efficiencies as high as 97% for the experiment run at [kLa]g value of 1421.8 h−1 and 96% for the experiment run at [kLa]g value of 9.6 × 1037 h−1 were verified before and after the addition of Serratia marcescens SA30, respectively. The resistance of mass transfer could be dependent on external mass transfer that controls the transport of nitrogen molecule along the experimental period of 256 days. The increase in [kLa]g value leading to increased performance of the SBR was verified to contribute to the fu...

Over the decades the palm oil industry has managed some challen ging environmental concerns regarding land transformation and degradation, increas e in eutrophication, changing habitats of wildlife, pesticides runoff into inland wa tercourses, and probable climate change. Countries producing palm oil desire to do so in a more sustainable way that will leave the environment evergreen. Therefore this paper aims to encourage sustainable management of agro-industrial waste and its potenti al in making financial returns from the same waste. Hence, the study was conducted with the participation of seven local palm oil mills having different capacities and oper ation age. Attention was given to milling waste as they could cause serious environmenta l menace if unattended to properly. Milling waste includ es lignocellulosic palm biomas s namely the empty fruit bunches (EFB), oil palm shell (OPS), mesocarp fibres, pal m oil mill effluent (POME), and palm oil mill sludge (POMS), as well as solid waste generated from the further processing of these biomass into the palm oil fuel ashe s (POFA) and palm oil clinkers (POC). The opportunities available to the Malaysian pa lm oil industry and the financial benefits which may accr ue from waste generated during palm oil production process cannot be over emphasized.

Kinetic and mass transfer aspects of biosorption of oxidisable organic matter (OOM) from wastewater are important for better understanding of the mechanisms of granules initiation and development. The modified mass transfer factor models were used to predict the liquid–solid mass transfer rates of OOM biosorption from palm oil mill effluent (POME) attached to aerobic granular sludge (AGS) in a sequencing batch reactor (SBR). The variations of [kLa]g, [kLa]f and [kLa]d pursuant to time were verified to have a zigzag pattern due to the organic loading rate varies with a change in the quality of POME feeding the SBR. The influence of added Serratia marcescens SA30 on the rates of mass transfer would be very remarkable due to the effects of metabolites and biomass growth this can lead to a rapid utilisation of OOM accumulated into AGS. The maximum efficiencies of SBR reaching 48% for CODt removal at [kLa]g value of 3.054 h−1 and 68% for CODs removal at [kLa]g value of 21.012 h−1 were verified before the addition of S. marcescens SA30 and those reaching 68% for CODt removal at [kLa]g value of 1.229 × 1063 h−1 and 94% for CODs removal at [kLa]g value of 7.152 × 1064 h−1 were verified after the addition of S. marcescens SA30. The resistance of mass transfer could be dependent on external mass transfer, which controls the movement of organic molecules along the experimental period of POME fed the SBR without and with added S. marcescens SA30. The performance of SBR would increase with increase of [kLa]g value, and this provides new insight into dynamic response of the aerobic digestion to AGS development.

Biogranulation is an effective biological technology suitable for the treatment of various wastewaters. However, the major drawback of this technique is the long start-up period for biogranule development. Hence, the primary focus of this study was on cell surface hydrophobicity which is the main parameter that indicates cell agglomeration during the initial self-immobilization process of aerobic granulation. The effects of sludge concentration and magnetic activated carbon on cell surface hydrophobicity were investigated in this study. Response surface methodology (RSM) was applied to design, analyze, and optimize the outcome of the study. Experiments were performed at sludge concentration of 1,000-3,000 mg/L and magnetic activated carbon mass of 1-5 g/L with 24 hr of aeration time. The results show that both variables yielded a positive significant effect on the initial development of aerobic granulation with 56% surface hydrophobicity. Interaction effects between variables on the responses were significant with positive estimated interaction effect at all different measured aeration time. The magnetic activated carbon acted as nuclei to induce bacterial attachment and further enhanced the initial process of biogranule development under optimal condition of 1:1.1 (sludge concentration: magnetic activated carbon). PRACTITIONER POINTS: Cell surface hydrophobicity was evaluated Magnetic activated carbon enhanced cell surface hydrophobicity Response surface methodology was employed for analyses Magnetic activate carbon mass and biomass concentration was significant Magnetic activated carbon acted as nuclei to improve biogranulation.

Sludge bulking caused by filamentous microorganisms is one of the prevailing operational problems in activated sludge process. Its severity is determined by the relative abundance of filame...

Palm oil mill effluent (POME) is categorized as high strength wastewater. The current treatment technology for POME is mostly depends on biological treatment through anaerobic and aerobic processes. Application of magnetic field was reported able to show effective removal performance of pollutant. The exposure of magnetic field will cause changes on the physical and chemical properties on a molecular level. The main objective of this research is to evaluate the application of EMF to enhance the performance of acetogenic microbes towards POME treatment. In this study, the EMF was evaluated in batch reactor system under an anaerobic acetogenic condition followed by aerobic reaction phase to treat POME. The hydraulic retention time and the intensity of EMF applied in this study were five days and ±15 mT respectively. The results indicated that using EMF improves the removal performance of color by 19%, chemical oxygen demand (COD) by 28%, ammonia nitrogen by 13%, nitrite by 17% and nitrate by 31%. Ultimately, the application of EMF helps to enhance anaerobic acetogenic bacteria and then enhanced the overall removal performance.

Aerobic granulation is a promising technology that has increasingly attracted global attention due to its potential as a cost effective system, and its application in a wide range of wastewaters. Aerobic granules are highly structured suspended microbial aggregates capable of degrading biodegradable compounds with excellent settling properties, good pollutant removal and high resistance to toxic compounds. However, evidences show that granules formation in high strength wastewaters takes relatively much longer time at initial stages. This article reviews the state-of-the-art of the researches done on the factors influencing granulation at initial stage, with particular focus on the aggregation of microbial cells. In addition, this review discusses the effective approaches adopted for the enhancement of initial development of aerobic granules. Moreover, the current article highlights the mechanism of aerobic granulation at its initial stage, as well as other different approaches. Finally, future research directions to improve aerobic granules formation at the initial stage are discussed.

This study investigated the effect of various cations (Ca2+, Mg2+, Al3+, Mn2+, Zn2+) on the autoaggregation (AAg) and surface hydrophobicity (SHb) of three different bacteria (Brevibacillus panacihumi strain (ZB1), Lysinibacillus fusiformis strain (ZB2) and Enterococcus faecalis strain (ZL)) using a 2-level factorial design. The AAg ratio was measured from the changes in the absorbance of the media. Results show that ZB2 had maximum AAg for the three bacteria investigated. A microscopic clustering of cells was observed when Ca2+ was added to ZB2. The AAg was in the range of 62%, 58% and 34% for ZB2, ZB1 and ZL, respectively and correlated to the SHb. The aggregation and SHb of the microbial cells increased with increasing ionic strength due to the repulsive steric or overlap forces between the polymer covered surfaces. Ca2+ demonstrated a more significant effect on aggregation and SHb of microbial cells due to an attractive binding force.

This study evaluated the performance of aluminum and iron plate electrode systems on the continuous electrocoagulation of boron from produced water under varying conditions of retention time, initial concentration and electrode distance. The experimental data were validated for mass transfer resistance using the modified mass transfer factor (MMTF) model. Results show a similar trend for both electrode systems. Boron removal decreased from 78.7–60% for aluminum electrode and 67.3–53.3% for iron electrode with shortening retention time from 45 to 30 min.. Boron removal further decreased from 84 to 72.7 % for aluminum electrode and 76 to 61.3 % for iron electrode with increasing electrode distance from 0.5 cm to 1.5 cm. Analyses of the mass transfer resistance showed that the driving force (B) for boron mass transfer was concentration dependent and increased from 0.1037 to 0.4002 mg.g for aluminum electrode and 0.0445 to 0.1258 mg.g for iron electrode with increasing initial boron concentration from 5 to 15 mg/L. A similar trend was observed for the affinity between boron and the electroactive species. Analyses of boron mass transfer resistance related to the global and film mass transfer, and porous diffusion show that boron mass transfer resistance correlated to the film mass transfer for both electrode systems. Aluminum electrode system showed better performance for boron removal and higher mass transfer kinetics. This study clearly demonstrates that continuous electrocoagulation is a suitable alternative for boron removal from produced water.

Transportation system is an important part of the municipal solid waste management system, and also requires substantial investment and operational costs after the landfill. The further of the service route and the more the number of trucks ritation then the greater the operational costs to be incurred. Transportation system in the research location uses two methods, namely Hauled Container System/HCS (4 units) and Stationary Container System/SCS (19 units), each with 6 m³ capacity. Armroll truck activity analysis found that one time ritation takes an average of 2.72 hours and the average amount of ritation is 3 rit / day. The operational cost required for the armroll truck is 13.433.68 IDR / m³ / day. The result of dump truck activity analysis obtained the average time in one ritation is 4.77 hours, with the amount of ritation of 2 rit / day. Operating cost for dump truck is 25.400.1 IDR / m³ / day so HCS method with armroll truck is more effective than SCS method with dump truck, although the number of units is less in the research location, this is due to the investment cost of the carosery which is slightly larger than the dump truck.

This study examined the degradation of pesticide aqueous solution containing chlorpyrifos, cypermethrin and chlorothalonil by the FeGAC/H2O2 process. Under the operating conditions (FeGAC 5 g/L, H2O2 concentration 100 mg/L and pH 3), chemical oxygen demand (COD) and total organic carbon removal were 96.2 and 79.2%, respectively, and biodegradability (BOD5/COD ratio) increased from 0 to 0.40 after 60 min reaction. Complete degradation of chlorpyrifos, cypermethrin and chlorothalonil pesticides active ingredients occurred in 1 min. Kinetic models such as pseudo-first-order, pseudo-second-order and intraparticle diffusion were evaluated. The Fourier transform infrared spectra (treated and untreated pesticide aqueous solutions) also indicated modification and/or degradation of the pesticide organic bonds. The study showed that FeGAC/H2O2 process can be used for the pretreatment of pesticide aqueous solution containing chlorpyrifos, cypermethrin and chlorothalonil before further treatment by biological...

A pilot-scale sequential batch reactor (SBR) biogranular system for the treatment of actual textile wastewater was developed in this study. The reactor had a working volume of 70 L and was operated according to SBR’s sequence for 24-hr cycle, which includes sequential anaerobic and aerobic reaction phases. Wastewater from two textile mills were used as feed, while sewage and pineapple wastewater were used as co-substrate. After operating the system for 60 d, 30% of the sludge had transformed into biogranules and had increased to 67% at the end of the study. The biogranules developed in the reactor have sizes ranging from 0.2 mm to 9.5 mm with a mean settling velocity of 28 ± 7 m/hr and sludge volume index of 73.9 mL/g. At the end of the study, the system yields 92% removal of COD, but the color removal oscillated throughout the development period in the range of 50 to 70%. Although the biogranules development is much faster in lab-scale reactor under controlled environment, the findings indicate the feasibility of developing biogranules in a bigger scale reactor using actual textile wastewater and other high-strength biodegradable wastewater as co-substrate.

Aggregation and surface hydrophobicity are two important indicators used to evaluate the successful development of biogranules. The effect of substrate concentration, pH, and temperature on these properties of selected bacteria that are isolated from biogranules used in treating textile wastewater was investigated. Statistical response surface methodology was used to quantitatively determine the effects and to determine the relationship between the responses and variables. Thirty experimental runs were performed at substrate concentrations of 500–3000 mg L −1 , pH of 5–9, and temperatures of 20–40 °C. The results show that all variables investigated were either positively or negatively correlated with aggregation and surface hydrophobicity and induced significant linear responses in these indicators. Interaction effects were also observed for some of the variables. An acceptable statistical model describing the relationship between aggregation and surface hydrophobicity of the selected bacteria and substrate concentration, pH, and temperature has been developed for the stated experimental conditions.

In this study, activated sludge was exposed by magnetic field exhibited from NdFeB – type of permanent magnets. The exposure was aimed to improve the physical properties of the activated sludge used in treating wastewater. Hence, it was hypothesized that the magnetically-exposed activated sludge is potential in enhancing the efficiency of removal performances of the wastewater treatment processes. The influence of magnetic field, exposure time, biomass concentration and mixing intensity on turbidity reduction, aggregation and settling velocity was thoroughly investigated. Response surface methodology (RSM) was applied for experimental design, analysis and optimization. Based on the results, magnetically-exposed activated sludge displayed certain trends showing that its properties were positively affected by magnetic field. At the optimum conditions of magnetic field of 88.0 mT, exposure time of 38.5 hrs, biomass concentration of 3380 mg/L and mixing intensity of 345 rpm achieved 68.3%, 60.1% and 0.0104 cm/s of turbidity reduction, aggregation and settling velocity, respectively.

This paper presents the effect of different sizes of palm kernel shell (PKS) activated carbon as the carrier material in a micro-bioreactor system to treat the palm oil mill effluent (POME). Three different sizes of PKS activated carbon were used as the carrier material, i.e. 4.750 – 2.360 mm (large), 1.180 – 0.710 mm (average) and 0.425 – 0.300 mm (small). The systems were run for a total of 29 days under hydraulic retention time (HRT) of 24 hours. The performances of several effluent quality parameters of POME regarding the use of PKS activated carbon of different sizes were studied. PKS activated carbon with size 1.180 – 0.710 mm showed the highest removal performances for chemical oxygen demand (COD), ammoniacal-nitrogen (AN), and solids, with 41 %, 84.6 %, and 88 % of removal respectively. The system with PKS activated carbon of size 4.750 - 2.360 mm showed the highest performance in removing TP (45 %), while 1.180 – 0.710 mm size of PKS activated carbon showed the highest performance in removing TN (53 %). The system was also found to effectively reduce the effluent colour. In overall, the PKS activated carbon of size 1.180 – 0.710 mm showed the best results as a carrier material to be used in the micro-bioreactor system in treating POME compared to the other two sizes.

In this study, four dye-degrading bacteria, Bacillus pumilus strain ZK1, Bacillus cereus strain ZK2, Brevibacillus panacihumi strain ZB1, and Lysinibacillus fusiformis strain ZB2 were used for the development of granule. Sterile sludge was used as seeding agent in a sequencing batch reactor under intermittent facultative anaerobic–aerobic system followed by subsequent textile wastewater treatment. Physical and morphological characteristics of the granules were determined after 112 d of development time. The average size of the mature granules reached 3.3 ± 1 mm, with integrity coefficient of 25 ± 2, settling velocity of 56 ± 5 m h−1, and sludge volume index of 35 ± 5.5 mL g−1. Mixed liquor suspended solids and mixed liquor volatile suspended solids were 12.9 ± 0.8 and 11 ± 0.6 g L−1, respectively. The developed granules showed 61% of decolorization and 46% of COD removal at HRT of 24 h. The population distribution of the bacteria consortium in mature granules developed into subsequent ratio of 1:4...

The fundamental understanding of mass transfer kinetics is essential for biosorption of phosphorus by aerobic granular sludge (AGS) to gain an insight into biological processes regarding the treatment of wastewater with high organic load. The removal of phosphorus by AGS from palm oil mill effluent was performed in a sequencing batch reactor (SBR) while the experimental data were assessed using the modified mass transfer factor (MMTF) models to get better understanding on the mechanisms of external and internal mass transfer. A zigzag pattern of the [kLa]g, [kLa]f and [kLa]d variations was verified before and after addition of Serratia marcescens SA30 due to the variations of organic loading rate and total phosphorus concentration were observed at every additional 50% new sample into the SBR. This study verified that the biosorption process is controlled by transport of phosphorus through a film of external fitting AGS. The analysis of SBR performance shows a logarithmic increase in the efficiency of phosphorus removal with increasing of the [kLa]g value. A new insight of the dynamic AGS growth of biological process revealed by the MMTF models may contribute to the advanced treatment of high organic content wastewater.

The excessive inhalation of pollutant particles with aerodynamic diameters less than 2.5 µm (PM2.5) results in risking the human respiratory health. The aim of this study is to investigate the possible pathways of long range and local tranportation for PM2.5 sources. The route patterns are analyzed by using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT 4.9) software during August 2017 to January 2018, covering three main monsoon seasons of Malaysia; southwest (SW), intermonsoon (IM) and northeast (NE) monsoon. This study represents the 72 h air mass backward trajectories in a mixed commercial-residential-industrial site of Skudai, Johor Bahru. The identified source origins are largely varied with different monsoon seasons and meteorological factors. The air-flow at different altitudes results in different effects, as the trajectory at height 500 m contributes to the greatest impact on the pollution level. The potential sources were generally from the Sumatera, Indonesia, during SW monsoon and China, during NE monsoon. The PM2.5 exceedance pattern in the Skudai area is also strongly influenced by the localized circulation, anthropogenic emission and dispersion characteristics. The increased levels of PM2.5 are predominantly contributed by the primary sources of vehicular emissions and industrial activities.

The adequacy of chemicals as coagulants such as alum is all around perceived. Nevertheless, there are numerous drawbacks related with the use including high operational costs, impeding impacts on human wellbeing and generation of huge sludge volumes. In this manner, it is crucial to supplant these chemical coagulants with organic-based coagulants to minimize the downsides. Therefore, the aim of this study is to identify the suitability of selected local wastes in becoming organic-based coagulant as to treat raw water. Regarding choice of organic-based coagulants, this study focused on the local waste materials, which are chestnut peels, bagasse and maize cobs. These waste materials were prepared by washing, drying, grinding lastly sieving in obtaining powder of coagulants ready to be used. A jar test was then performed to decide the effect of individual characteristic coagulants on the effectiveness of turbidity removal under different working variables of pH and coagulant dosage. Based on the findings, bagasse contributed to the highest yield of 79.5% followed by chestnut and maize cob. From the jar test experiments, the optimum dosage of 90 mg/L and pH 7.5 was obtained. At these optimizations, highest turbidity removal of 97.3% was recorded by bagasse compared to the other tested natural coagulants. This showing that bagasse as one of the representatives of organic wastes has the potential to physically treat the water. Keywords: Organic-based coagulant; Organic wastes; Coagulant dosage; Turbidity removal.

An integrated hybrid bioreactor (IHB) and integrated suspended bioreactor (ISB) coupling aerobic, anoxic and settling units was evaluated for industrial wastewater treatment with and without the installation of a rectangular hollow engraved submerged Perspex media in the aerobic unit. Bioreactor performance was examined at different overall hydraulic retention times of 36, 12, 7.2, 5.1 and 4 days, respectively. Nitrogen mass balance was analyzed to examine the inhibitory effects of metabolic by-products on nitrification in IHB. Both bioreactors exhibited a short start-up period during acclimatization. Results show a lower effluent COD concentration of 15–85 mg/L in IHB and 38.6–124 mg/L in ISB. Effluent ammonia-nitrogen was 0.65–3.5 mg/L in IHB and 0.3–4.5 mg/L in ISB. Effluent nitrate and nitrite were low in both bioreactors but lower in IHB. Mass balance analysis in IHB indicated that nitrate was the dominant ammonia metabolite and decreased with reducing HRT. Microfauna investigation showed that free swimmers, crawling and attached ciliates were major protozoans in IHB while free swimmers and attached ciliates were dominant protozoans in ISB. Kinetic evaluation demonstrates that microbial growth was higher in IHB. The Y, kd, μmax and Ks for IHB was 0.1 g VSS/g COD, 0.02 per day, 0.81 per day and 1.26 g/m3 with a correlation coefficient (R2) of 0.978 while it was 0.118 g VSS/g COD, 0.04 per day, 0.635 per day and 3.93 g/m3 with a correlation coefficient (R2) of 0.988 in ISB. This study demonstrates that while both ISB and IHB were effective for industrial wastewater treatment, IHB performance was comparatively higher due to the inclusion of the submerged media.