Turning waste to wealth-biodegradable plastics polyhydroxyalkanoates from palm oil mill effluent – a Malaysian perspective

Palm oil industries have been contributing significantly towards the country’s economy and increase standard of living among Malaysians. However, it has also been identified as the major contributor for discharging the largest pollution load throughout the country. Owing to high biochemical oxygen demand (BOD) and chemical oxygen demand (COD), the palm oil mill effluent (POME) cannot be discharged directly into the environment. Thus, palm oil industries are facing tremendous challenges in order to comply with environmental regulations. While anaerobic digestion has been employed by most mills as primary treatment, POME can also be a potential source of degradable organic material which can be converted into value-added products and fine chemicals. Organic acids generated during acid-phase anaerobic digestion of POME could be a potential carbon source for the production of polyhydroxyalkanoates (PHA)- a biodegradable thermoplastic material of microbial origin. This paper aims at understanding how organic acids from POME may serve as a renewable feedstock for the biosynthesis of PHA.     

Efficient removal of heavy metals from electroplating wastewater using polymer ligands

Poly(hydroxamic acid)-poly(amidoxime) chelating ligands were synthesized from poly(methyl acrylate-co-acrylonitrile) grafted acacia cellulose for removing toxic metal ions from industrial wastewaters. These ligands showed higher adsorption capacity to copper (2.80 mmol?g⁻¹) at pH 6. In addition, sorption capacities to other metal ions such as iron, zinc, chromium, and nickel were also found high at pH 6. The metal ions sorption rate (t_1/2) was very fast. The rate of adsorption of copper, iron, zinc, chromium, nickel, cobalt, cadmium and lead were 4, 5, 7, 5, 5, 8, 9 and 11 min, respectively. Therefore, these ligands have an advantage to the metal ions removal using the column technique. We have successfully investigated the known concentration of metal ions using various parameters, which is essential for designing a fixed bed column with ligands. The wastewater from electroplating plants used in this study, having chromium, zinc, nickel, copper and iron, etc. For chromium wastewater, ICP analysis showed that the Cr removal was 99.8% and other metal ions such as Cu, Ni, Fe, Zn, Cd, Pb, Co and Mn removal were 94.7%, 99.2%, 99.9%, 99.9%, 99.5%, 99.9%, 95.6% and 97.6%, respectively. In case of cyanide wastewater, the metal removal, especially Ni and Zn removal were 96.5 and 95.2% at higher initial concentration. For acid/alkali wastewater, metal ions removing for Cd, Cr and Fe were 99.2%, 99.5% and 99.9%, respectively. Overall, these ligands are useful for metal removal by column method from industrial wastewater especially plating wastewater.     

The effects of application of agricultural wastes to firing range soil on metal accumulation in Ipomoea aquatica and soil metal bioavailability

The immobilisation of heavy metals in the soil of a 25-year-old active firing range using durian (Durio zibethinus L.) tree sawdust (DTS), coconut coir (CC) and oil palm empty fruit bunch (EFB) was investigated. The immobilisation effects were evaluated in terms of metal accumulation in water spinach (Ipomoea aquatica) and soil metal bioavailability. A pot experiment was conducted by amending the firing range soil with DTS, CC and EFB at application rates of 0%, 1% and 3% (w/w), respectively. All amendments increased the biomass yield and reduced the uptake of heavy metals in the plant tissue. Zn had the highest values of Bioconcentration Factor (BCF: 0.301–0.865) and Translocation Factor (TF: 1.056–1.883). Pb was the least-accumulated and transported metal in the plant tissues, with the BCF and TF values of 0.019–0.048 and 0.038–0.116, respectively. The bioavailable fraction of heavy metals in the firing range soil decreased following the application of the three agricultural wastes studied. DTS, CC and EFB did not cause toxicity symptoms in the water spinach over the pot experiment. Therefore, DTS, CC and EFB are considered promising immobilising agents for the remediation of metal-contaminated land.     

Application of enrichment factor,geoaccumulation index,and ecological risk index in assessing the elemental pollution status of surface sediments

Environmental Geochemistry and Health - Sediment can accumulate trace elements in the environment. This study profiled the magnitude of As, Ba, Cd, Co, Cu, Cr, Ni, Pb, Se, and Zn pollution in...     

Landfill leachate treatment using sub-surface flow constructed wetland by Cyperus haspan

Performance evaluation of pilot scale sub-surface constructed wetlands was carried out in treating leachate from Pulau Burung Sanitary Landfill (PBSL). The constructed wetland was planted with Cyperus haspan with sand and gravel used as substrate media. The experiment was operated for three weeks retention time and during the experimentation, the influent and effluent samples were tested for its pH, turbidity, color, total suspended solid (TSS), chemical oxygen demand (COD), biochemical oxygen demand (BOD(5)), ammonia nitrogen (NH(3)-N), Total phosphorus (TP), total nitrogen (TN) and also for heavy metals such as iron (Fe), magnesium (Mg), manganese (Mn) and zinc (Zn) concentrations. The results showed that the constructed wetlands with C. haspan were capable of removing 7.2-12.4% of pH, 39.3-86.6% of turbidity, 63.5-86.6% of color, 59.7-98.8% of TSS, 39.2-91.8% of COD, 60.8-78.7% of BOD(5), 29.8-53.8% of NH(3)-N, 59.8-99.7% of TP, 33.8-67.0% of TN, 34.9-59.0% of Fe, 29.0-75.0% of Mg, 51.2-70.5% of Mn, and 75.9-89.4% of Zn. The significance of removal was manifested in the quality of the effluent obtained at the end of the study. High removal efficiencies in the study proved that leachate could be treated effectively using subsurface constructed wetlands with C. haspan plant.     

Cerium dioxide and composites for the removal of toxic metal ions

The presence of contaminants in potable water is a cause of worldwide concern. In particular, the presence of metals such as arsenic, lead, cadmium, mercury, chromium can affect human health. There is thus a need for advanced techniques of water decontamination. Adsorbents based on cerium dioxide (CeO₂), also named ‘ceria,’ have been used to remove contaminants such as arsenic, fluoride, lead and cadmium. Ceria and composites display high surface area, controlled porosity and morphology, and abundance of functional groups. They have already found usage in many applications including optical, semiconductor and catalysis. Exploiting their attractive features for water treatment would unravel their potential. We review the potential of ceria and its composites for the removal of toxic metal ions from aqueous medium. The article discusses toxic contaminants in water and their impact on human health; the synthesis and adsorptive behavior of ceria-based materials including the role of morphology and surface area on the adsorption capacity, best fit adsorption isotherms, kinetic models, possible mechanisms, regeneration of adsorbents; and future perspectives of using metal oxides such as ceria. The focus of the report is the generation of cost-effective oxides of rare-earth metal, cerium, in their standalone and composite forms for contaminant removal.     

Fungicidal impact on chickpea--Mesorhizobium symbiosis

The effects of carbendazim, captan, thiram, and mancozeb, on plant vitality, chlorophyll content, N uptake, protein content, nodulation, and seed yield in chickpea (Cicer arietinun) were assessed in a controlled environment. Seeds treated with fungicides at 1 and 1.5 g.a.i. kg seed had no significant adverse effect on plant vigor, seed yield, and N and protein contents. In contrast, fungicides applied at 2 g.a.i./kg of captan, thiram and mancozeb, significantly reduced the measured parameters. In general, the toxicity of fungicides in terms of seed yield increased in the following order: Control=carbendazim > thiram > captan > mancozeb. Total chlorophyll content in foliage declined consistently with fungicides dose rates and application days. Seeds treated with lower rates of fungicides significantly increased nodulation (nodule number per plant and its dry mass) and were compatible with chickpea inoculum used in this study. Although carbendazim at 2 g.a.i. kg seed had no phytotoxic effect assessed under greenhouse conditions, it significantly reduced the chlorophyll content, nodulation (60d) and N content in shoots.     

Effects of different pretreatment methods on anaerobic mixed microflora for hydrogen production and COD reduction from palm oil mill effluent

Effects of different pretreatment methods on sludge inocula were evaluated with respect to hydrogen (H₂) production enhancement using palm oil mill effluent (POME) in a batch system. The experimental results showed that the pretreatment methods (chemical, acid, heat-shock, freezing and thawing, and base) at 35 °C and initial pH 5.5 had a positive influence on H₂ production yield and chemical oxygen demand (COD) removal efficiency during the fermentative H₂ production as compared to the control experiments (without pretreatment). Heat-shock pretreatment method was shown to be a simple and useful method for enhancing both H₂ producing and COD removal processes from POME with highest H₂ yield and COD removal efficiency at 0.41 mmol H₂/g COD and 86%, respectively.     

Tolerance and biosorption of copper （Cu） and lead （Pb） by filamentous fungi isolated from a freshwater ecosystem

Filamentous fungi are able to accumulate significant amount of metals from their environment. The potential of fungal biomass as agents for biosorption of heavy metals from contaminated sediments is currently receiving attention. In the present study, a total of 41 isolates of filamentous fungi obtained from the sediment of the Langat River, Selangor, Malaysia were screened for their tolerance and uptake capability of copper (Cu) and lead (Pb). The isolates were identified as Aspergillus niger, A. fumigatus, Trichoderma asperellum, Penicillium simplicissimum and P. janthinellum. A. niger and P. simplicissimum, were able to survive at 1000 mg/L of Cu(II) concentration on Potato Dextrose Agar (PDA) while for Pb, only A. niger survived at 5000 mg/L concentration. The results showed that A. niger, P. simplicissimum and T. asperellum have a better uptake capacity for Pb compared to Cu and the findings indicated promising biosorption of Cu and Pb by these filamentous fungi from aqueous solution. The present study was also determined the maximum removal of Cu(II) and Pb(II) that was performed by A. niger. The metal removal which occurred at Cu(II) 200 mg/L was (20.910 0.581) mg/g and at 250 mg/L of Pb(II) was (54.046 0.328) mg/g.