Biological-chemical treatment of polycyclic aromatic hydrocarbon contaminated soil / Salina Alias

Industrialization has caused a great deal of environmental pollutions such as soil contamination via deposition and spillage of contaminants. One of the major contaminants is high molecular weight (HMW) polycyclic aromatic hydrocarbon (PAH), specifically the benzo(a)pyrene. Benzo(a)pyrene is known for its carcinogenic effect. Several soil remediation strategies have been proposed. However, to date, remediation of benzo(a)pyrene contaminated soil using zero-valent iron (ZVI) and hybrid bacteria-ZVI has not been investigated. The capability of bacteria, namely, Corynebacterium urealyticum and Sphingobacterium spiritovorum to degrade benzo(a)pyrene in soil were firstly investigated in three conditions, single, binary and ternary substrate experiments. Binary and ternary substrate experiments involved the degradation of benzo(a)pyrene, a HMW-PAH with the presence of low molecular weight (LMW) PAH. It was found that both bacteria were capable of degrading the benzo(a)pyrene in the presence of anthracene and phenanthrene (both are LMW-PAHs). However the degree of degradation varied. For instance, the degradation of benzo(a)pyrene was enhanced with the presence of anthracene and phenanthrene in ternary substrate experiment, where 30% of benzo(a)pyrene was degraded. In the single and binary substrate experiment which only phenanthrene was present, about 24% and 14% of benzo(a)pyrene was degraded. Both bacteria degraded the benzo(a)pyrene at the rate of 1.508 - 3.229 mg/kg/day. Then, the ability of ZVI, an engineered iron particles to facilitate in the oxidation of benzo(a)pyrene, was evaluated in single and mixed PAHs experiments with different ZVI concentrations. In this case, it was found that the higher the dosage of ZVI in the soil, the more benzo(a)pyrene was oxidized. The degradation rates for ZVI oxidation were at 0.154 - 0.718 mg/kg/minutes which is 150 times higher than the biological treatment. The soil contaminated by benzo(a)pyrene was then sequentially and simultaneously remediated with bacteria and ZVI in hybrid treatment approaches. A slight enhancement in the removal of benzo(a)pyrene was found in the hybrid treatment compared to the individual treatment approach. However, the most effective hybrid approach was through the sequence treatment with bacteria {Sphingobacterium spiritovorum) followed by ZVI. In this, 48% of benzo(a)pyrene was removed. The maximum biotic and abiotic conditions for the efficient remediation strategy of benzo(a)pyrene were also investigated. It was found that concentration of bacteria at CFU 108/g, temperature 35°C and pH 4 were the maximum conditions for the hybrid bacteria-ZVI. Mathematical models to predict benzo(a)pyrene removal using S. spiritovorum-biologicdiX treatment, ZVI-chemical treatment and hybrid S. spiritovorum-ZVl were successfully developed and validated in this study. The proposed models were able to provide prediction of benzo(a)pyrene removal that will help engineers to plan and design the remediation strategy in order to minimize the impact of PAH contamination on human and environment

Characterization and performance of rice husk as additive in green ceramic water filter fabricated by slip-casting

Purpose The purpose of this study is to investigate the using of rice husk (RH) which is a green material derived from agricultural waste with the ability to absorb heavy metal. It has been used in wastewater treatment. In this research, a kaolin-based green ceramic water filter (CWF) incorporated with two different additives (RH and zeolite-based RH ash [RHA]) was successfully fabricated. Design/methodology/approach The weight ratio of kaolin:additive was varied (90:10, 80:20 and 70:30) and fabricated via the slip-casting technique. The green CWFs were dried (60°C for 1 h), followed by sintering (1,200°C). Findings The green CWF of kaolin:RH with a weight ratio of 70:30 showed the best properties and satisfactory performance with a porous cross-section microstructure, highest porous area (4.58 µm2), good structure, lowest shrinkage (8.00%), highest porosity (45.10%), lowest density (1.79 g cm−3), highest water absorption (55.50%) and hardness (241.40 Hv). This green CWF has also achieved good permeability (42.00 L m−2h−1) and removal of the textile dye (27.88%). The satisfactory characterization and good textile dye removal performance (75.47%) were also achieved from green CWF with kaolin:zeolite at a weight ratio of 80:20. Research limitations/implications This research is focused on green CWF and zeolite at a certain amount with the specific characterization analysis methods. Practical implications The use of low-cost waste materials to treat dye wastewater from agricultural by-products/wastes sources in treating the dye will enhance the using of green material. Social implications Avoiding the waste sludge that can pollute the environment can create a health issue. The use of low-cost waste materials to treat dye wastewater from agricultural by-products/wastes sources in treating the dye can avoid the waste sludge that can pollute the environment and create serious health issue. Originality/value All the kaolin-based green CWFs incorporated with two different additives (RH and zeolite-based RHA) fabricated using a simple slip-casting technique have shown the potential to be used as a filter in wastewater treatment applications

Degradation of Phenanthrene in Liquid Culture and Sand Slurry by Corynebacterium urealyticum

Most studies on PAHs biodegradation evaluated the degradation potential of microorganisms under indigenous condition in either liquid or solid. There are limited studies on evaluation of the same microorganisms in degrading PAHs under non-indigenous condition in both liquid and solid media. This study investigated the potential of the bacterium, Corynebacterium urealyticum isolated from municipal sludge in degrading phenanthrene in both liquid and solid media. Batch experiments were conducted over 20 days. Batch reactors containing artificially contaminated phenanthrene minimal media and sand slurry were inoculated with bacterium culture. Percentage phenanthrene degradation in liquid culture and sand slurry were found to be 87% and 29%, respectively. Apart of having higher rate in liquid culture, the degradation activity by bacterium remain active throughout the experiment.  There were no significant differences on the degradation of phenanthrene at low and high initial phenanthrene concentrations in liquid cultures, which differed to the observation in sand slurry. From the viable count analysis, it was observed that this bacterium immediately adapted to the new environment. This study shows that Corynebacterium urealyticum show better capability in degrading phenanthrene in liquid culture compared to sand slurry. Keywords: Bioremediation, Corynebacterium urealyticum, liquid cultures, Phenanthrene, sand slurry

Colour removal from industrial wastewater using bladderwort as adsorption media / Salina Alias, Amalina Amirah Abu Bakar, Nor Azliza Akbar and Siti Normasyarah Muhamed

Adsorption process in wastewater treatment using natural products has become popular due to its low cost and environmentally friendly approach. However, less attention has been focused on the ability of aquatic plant species such as Bladderwort as an adsorption media. This paper discusses the effectiveness of using Bladderwort as a natural adsorbent for the removal of colour from wastewater. Under batch technique, the effect on adsorbent size (75-600 μm), wastewater pH (pH 1-12) and agitation speed (50-250 rpm) was determined. The results indicated that the removal efficiency of colour is in tandem with the size of Bladderwort as higher size particles have more efficiency on removal of colour. Besides, the wastewater pH also plays a major role in the colour removal efficiency where the highest removal was observed in acidic condition compared to alkali. However, the agitation speed is least affected in the removal of colour. The optimum size of Bladderwort and pH to effectively remove the colour was at 600 μm and pH 3

Evaluation of ampicillin, vancomycin, and gentamycin antibiotic resistant among lactobacillus isolates / Rozila Alias... [et al.]

Antibiotic resistance is an ever-increasing in worldwide problem nowadays. It is happened when the exten- sive use of antibiotics which will creates the selective pressure resulting from mutation of normal genes and spreading of a variety of an antimicrobial resistance. Uses of Lactobacillus as probiotics or in starter cultures may serve as hosts of antibiotic resistance genes, which could be transfer or resistance to multiple antibiotics. Therefore, it is important to screen the susceptible or resistance towards antibiotics which will not transferable resistance genes. In the recent study, a total of 37 strains of Lactobacillus species isolated from various milk and dairy products such as goat’s milk, cattle’s milk, human’s milk, homemade yogurt and commercial yogurt were examined for the antibiotic profile using Kirby-Bauer method. The results of this study show that human’s milk has a high number of Lactobacillus isolates resistant to ampicillin (75%), vancomycin (62.5%) and gentamycin (62.5%). Whereas Lactobacillus isolated from cattle’s milk have resistant to ampicillin (42.1%), vancomycin (42.1%) and susceptible to gentamycin (0%). But however, goat’s milk still has lower percentage number of resistant to ampicillin (28.0%), vancomycin (14.3%) and are susceptible to gentamycin (0%). These results indicate that ampicillin and vancomycin resistant seems to be very common among Lactobacillus isolates but gentamycin are still susceptible used. Vancomycin resistant are more concerned because of the emerging problem in hospital and often described as one of the last resorts against the infection caused by multidrug-resistant pathogens. Therefore, lactobacilli as probiot- ics would be more monitoring when applied in food industry and clinical especially for immune compromised patients or during anti-biotherapy. Acquisition and retransfer of resistance genes should be addressed in the new safety aspects of probiotics uses.addressed in the new safety aspects of probiotics uses

Recovery of Plastic Waste

Global plastic waste production had increased from 245 million metric tons in 2008 to 359 million metric tons in 2018, and this value is expected to be boosted by three times in the year 2050. The sudden change of human lifestyle during the pandemic of Covid-19 toward online shopping and panic buying to restock kitchen shelves has resulted in a high impact on the plastic industry and plastic waste management. The pandemic requires significant plastic waste management changes and severely affected plastic waste reduction’s current policies and strategies. Valorization of plastic is a desirable approach in managing a sudden surge of plastic waste during the outbreak of the covid-19 pandemic as this recovery approach will change the plastic waste into valuable products. The present study reviews the current technologies on the recovery approaches of plastic into valuable products. The recovery approaches that cover mechanical recycling, energy recovery, and chemical recovery are discussed. The concept, mechanism, and performance of each approach are reviewed. The use of plastic in concrete, road construction, and soil treatment is highlighted under mechanical recovery. The heating value of plastic waste is used to discuss plastic waste combustion through the incineration process for energy recovery. The chemical recovery involves depolymerizing plastic waste through chemolysis, and thermolysis is discussed and compared. The review can conclude that the current technologies in the recovery of plastic waste will improve waste management, sustainability of resources, and shift toward the circular economy

Engineering Behavior of Concrete with Recycled Aggregate

Concrete is extensively used as construction materials in Malaysia. Concrete contributes suitable feature for construction industry for instance durability, adequate compressive strength, fire resistance, availability and is economic as compared to other construction materials. Depletion of natural resources and disposal of construction and demolition waste remarkably claim environmental threat. In this paper, the engineering behavior, durability, and concrete microstructure of recycled concrete aggregates (RCA) on short-term concrete properties were investigated. The studied concrete at design mix proportion of 1:0.55:2.14:2.61 (weight of cement :coarse aggregates :sand :water) used to obtain medium-high compressive strength with 20%, 50%, and 100% of RCA. Results show that for the same water/cement ratio, RCA replacement up to 50% still achieved the targeted compressive strength of 25 MPa at 28 curing days. Addition, at similar RCA replacement, the highest carbonation depth value was found at 1.03 mm which could be attributed to the pozzolanic reaction, thus led to lower carbonation resistance. Scanning electron microscopy microstructure shows that the RCA surface was porous and covered with loose particles. Moreover, the interfacial transition zone was composed of numerous small pores, micro cracks, and fissures that surround the mortar matrix. On the basis of the obtained results, recommendable mineral admixtures of RCA are necessary to enhance the quality of concrete construction

Engineering Behavior of Concrete with Recycled Aggregate

Concrete is extensively used as construction materials in Malaysia. Concrete contributes suitable feature for construction industry for instance durability, adequate compressive strength, fire resistance, availability and is economic as compared to other construction materials. Depletion of natural resources and disposal of construction and demolition waste remarkably claim environmental threat. In this paper, the engineering behavior, durability, and concrete microstructure of recycled concrete aggregates (RCA) on short-term concrete properties were investigated. The studied concrete at design mix proportion of 1:0.55:2.14:2.61 (weight of cement :coarse aggregates :sand :water) used to obtain medium-high compressive strength with 20%, 50%, and 100% of RCA. Results show that for the same water/cement ratio, RCA replacement up to 50% still achieved the targeted compressive strength of 25 MPa at 28 curing days. Addition, at similar RCA replacement, the highest carbonation depth value was found at 1.03 mm which could be attributed to the pozzolanic reaction, thus led to lower carbonation resistance. Scanning electron microscopy microstructure shows that the RCA surface was porous and covered with loose particles. Moreover, the interfacial transition zone was composed of numerous small pores, micro cracks, and fissures that surround the mortar matrix. On the basis of the obtained results, recommendable mineral admixtures of RCA are necessary to enhance the quality of concrete construction