Soil characteristics under cash crop farming in upland areas of Sarawak,Malaysia

This study discusses soil fertility under perennial cash crop farming (para rubber, Hevea brasiliensis; black pepper, Piper nigrum; oil palm, Elaeis guineensis) conducted by local farmers and an oil palm estate in an upland area of Sarawak, Malaysia, in comparison with the surrounding secondary forests. In the farmlands of the local farmers, rubber farming was conducted without fertilizer application, while 2–5 t ha^?1 of NPK compounds were applied annually on pepper farms. Soils under rubber farming were acidic with poor nutrient contents, resembling soils in secondary forests. In pepper farms, soils were less acidic and showed high nutrient contents, especially with respect to available P and exchangeable Ca. This trend became stronger with increasing farming duration. Fertilizers applied around pepper vines appeared to migrate and spread across the fields. Bulk density and hardness of surface soils were higher in pepper farms than in secondary forests, indicating soil compaction due to field works. In the oil palm estate, annual fertilizer application rates were moderate at 0.4–0.8 t ha^?1 of NPK compound fertilizers. However, the soil properties in the oil palm estate were similar to those of the small-scale pepper farms. Close to the bases of the palms where fertilizers usually are applied, the contents of exchangeable Ca and available P were high. Nutrient uptake by the dense root systems of the palms seemed to prevent excessive loss of nutrients through leaching. Loss of soil organic matter and deterioration of soil physical properties were brought about by terrace bench construction, but the soils seemed to recover to some extent over time. In conclusion, technologies such as intercropping and the appropriate allocation of different crops to specific locations as well as the proper selection and dosage of fertilizers should be developed and adopted to improve fertilizer efficiency and prevent water pollution due to fertilizer wash-off from farmlands.     

Distribution of Chironomidae (Insecta: Diptera) in polluted rivers of the Juru River Basin, Penang, Malaysia

The influence of physical and chemical parameters on the abundance and diversity of chironomids was studied in six rivers with moderate to highly polluted water in the Juru River Basin. The rivers: Ceruk Tok Kun (CTKR) as reference site, and polluted rivers of Pasir (PR), Juru (JR), Permatang Rawa (PRR), Ara (AR) and Kilang Ubi (KUR) were sampled over a period of five months (November 2007–March 2008). Nine chirnomid species: Chironimus kiiensis, C. javanus, Polypedilum trigonus, Microchironomus sp., Dicrotendipes sp., Tanytarsus formosanus, Clinotanypus sp., Tanypus punctipennis and Fittkauimyia sp. were identified. Assessment of their relationships with several environmental parameters was performed using the canonical correspondence analysis (CCA). Tanytarsus formosanus was the most dominant in the relatively clean CTKR and moderately polluted JR with mean densities of 19.66 and 25.32 m?2, respectively while C. kiiensis was abundant in more polluted rivers. Tanytarsus formosanus, Dicrotendipes sp. and Microchironomus sp. were grouped under moderate to high water temperature, total organic matter (TOM), total suspended solids (TSS), velocity, pH, phosphates and sulphates. However, Tanypus punctipennis, Fittkauimyia sp., and Clinotanypus sp. were associated with high contents of river sediment such as TOM, Zn and Mn and water ammonium-N and nitrate-N and they were associated with higher dissolved oxygen (DO) content in the water. Chironomus kiiensis, C. javanus and P. trigonus showed positive relationships with TOM, ammonium-N and nitrate-N as well as trace metals of Zn, Cu and Mn. These three species could be considered as tolerant species since they have the ability to survive in extreme environmental conditions with low DO and high concentrations of pollutants. Based on the water parameter scores in all rivers, the highest diversity of chironomid larvae was reported in CTKR. With higher concentrations of organic and/or inorganic pollutants as reported in PPR, KUR and AR, the chironomid larval diversity decreased, and the abundance of tolerant species, mainly Chironomus spp., increased.     

Chitosan for direct bioflocculation of wastewater

Environmental Chemistry Letters - Coagulation/flocculation is a major phenomenon occurring during industrial and municipal water treatment to remove suspended particles. Common coagulants are metal...     

Visible-light-driven photocatalytic dual-layer hollow fibre membrane ameliorates the changes of bisphenol A exposure in gastrointestinal tract

Environmental Science and Pollution Research - Various treatments of choice are available to overcome contamination of bisphenol A (BPA) in the environment including membrane technologies; however,...     

Preparation and characterization of glass hollow fiber membrane for water purification applications

This work discusses the preparation and characterizations of glass hollow fiber membranes prepared using zeolite-5A as a starting material. Zeolite was formed into a hollow fiber configuration using the phase inversion technique. It was later sintered at high temperatures to burn off organic materials and change the zeolite into glass membrane. A preliminary study, that used thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier transform infrared (FTIR), confirmed that zeolite used in this study changed to glass at temperatures above 1000 °C. The glass hollow fiber membranes prepared using the phase inversion technique has three different microstructures, namely (i) sandwich-like structure that originates from inner layer, (ii) sandwich-like that originates from outer layer, and (iii) symmetric sponge like. These variations were influenced by zeolite weight loading and the flow rate of water used to form the lumen. The separation performances of the glass hollow fiber membrane were studied using the pure water permeability and the rejection test of bovine serum albumin (BSA). The glass hollow fiber membrane prepared from using 48 wt% zeolite loading and bore fluid with 9 mL min^?1 flow rate has the highest BSA rejection of 85% with the water permeability of 0.7 L m^?2 h^?1 bar^?1. The results showed that the separation performance of glass hollow fiber membranes was in the ultrafiltration range, enabled the retention of solutes with molecular sizes larger than 67 kDa such as milk proteins, endotoxin pyrogen, virus, and colloidal silica.     

Mechanical, Thermal and Water Absorption Properties of Kenaf-Fiber-Based Polypropylene and Poly(Butylene Succinate) Composites

The use of composites made from non-biodegradable conventional plastic materials (e.g., polypropylene, PP) is creating global environmental concern. Biodegradable plastics such as poly(butylene succinate) (PBS) are sought after to reduce plastic waste accumulation. Unfortunately, these types of plastics are very costly; therefore, natural lignocellulosic fibers are incorporated to reduce the cost. Kenaf fibers are also incorporated into PP and PBS for reinforcing purposes and they have low densities, high specific properties and renewable sourcing. However without good compatibilization, the interfacial adhesion between the matrix and the fibers is poor due to differences in polarity between the two materials. Maleic anhydride-grafted compatibilizers may be introduced into the system to improve the matrix-fiber interactions. The overall mechanical, thermal and water absorption properties of PP and PBS composites prepared with 30 vol.% short kenaf fibers (KFs) using a twin-screw extruder were being investigated in this study. The flexural properties for both types of composites were enhanced by the addition of compatibilizer, with improvements of 56 and 16 % in flexural strength for the PP/KF and PBS/KF composites, respectively. Good matrix-fiber adhesion was also observed by scanning electron microscopy. However, the thermal stability of the PBS/KF composites was lower than that of the PP/KF composites. This result was confirmed by both DSC and TGA thermal analysis tests. The water absorption at equilibrium of a PBS composite filled with KFs is inherently lower than of a PP/KF composite because the water molecules more readily penetrate the PP composites through existing voids between the fibers and the matrix. Based on this research, it can be concluded that PBS/KF composites are good candidates for replacing PP/KF composites in applications whereby biodegradability is essential and no extreme thermal and moisture exposures are required.     

Removal of arsenic species from water by batch and column operations on bagasse fly ash

Bagasse fly ash (BFA, a sugar industrial waste) was used as low-cost adsorbent for the uptake of arsenate and arsenite species from water. The optimum conditions for the removal of both species of arsenic were as follows: pH 7.0, concentration 50.0 μg/L, contact time 50.0 min, adsorbent dose 3.0 g/L, and temperature 20.0 °C, with 95.0 and 89.5 % removal of arsenate and arsenite, respectively. The Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich adsorption isotherms were used to analyze the results. The results of these models indicated single-layer uniform adsorption on heterogeneous surface. Thermodynamic parameters, i.e., ΔG°, ΔH°, and ΔS°, were also calculated. At 20.0 to 30.0 °C, the values of ΔG° lie in the range of ?4,722.75 to ?4,878.82 and ?4,308.80 to ?4,451.73 while the values of ΔH° and ΔS° were ?149.90 and ?121.07, and 15.61 and 14.29 for arsenate and arsenite, respectively, indicating that adsorption is spontaneous and exothermic. Pseudo-first-order kinetics was followed. In column experiments, the adsorption decreased as the flow rate increased with the maximum removal of 98.9 and 95.6 % for arsenate and arsenite, respectively. The bed depth service time and Yoon and Nelson models were used to analyze the experimental data. The adsorption capacity (N _o) of BFA on column was 3.65 and 2.98 mg/cm³ for arsenate and arsenite, respectively. The developed system for the removal of arsenate and arsenite species is economic, rapid, and capable of working under natural conditions. It may be used for the removal of arsenic species from any contaminated water resources.     

On-site phytoremediation applicability assessment in Alur Ilmu,Universiti Kebangsaan Malaysia based on spatial and pollution removal analyses

The present paper aims to assess the phytoremediation performance based on pollution removal efficiency of the highly polluted region of Alur Ilmu urban river for its applicability of on-site treatment. Thirteen stations along Alur Ilmu were selected to produce thematic maps through spatial distribution analysis based on six water quality parameters of Malaysia’s Water Quality Index (WQI) for dry and raining seasons. The maps generated were used to identify the highly polluted region for phytoremediation applicability assessment. Four free-floating plants were tested in treating water samples from the highly polluted region under three different conditions, namely controlled, aerated and normal treatments. The selected free-floating plants were water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes), rose water lettuce (Pistia sp.) and pennywort (Centella asiatica). The results showed that Alur Ilmu was more polluted during dry season compared to raining season based on the water quality analysis. During dry season, four parameters were marked as polluted along Alur Ilmu, namely dissolve oxygen (DO), 4.72 mg/L (class III); ammoniacal nitrogen (NH₃–N), 0.85 mg/L (class IV); total suspended solid (TSS), 402 mg/L (class V) and biological oxygen demand (BOD), 3.89 mg/L (class III), whereas, two parameters were classed as polluted during raining season, namely total suspended solid (TSS), 571 mg/L (class V) and biological oxygen demand (BOD), 4.01 mg/L (class III). The thematic maps generated from spatial distribution analysis using Kriging gridding method showed that the highly polluted region was recorded at station AL 5. Hence, water samples were taken from this station for pollution removal analysis. All the free-floating plants were able to reduce TSS and COD in less than 14 days. However, water hyacinth showed the least detrimental effect from the phytoremediation process compared to other free-floating plants, thus made it a suitable free-floating plants to be used for on-site treatment.     

Extrication of biodiesel feedstock from early stage of food waste liquefaction

Biodiesel is commonly produced from vegetable oils, mostly edible and more expensive than petroleum diesel. By considering the cost of the conversion processes, cheap feedstock such as triglycerides and fatty acids (FA) extracted from early stage of food waste liquefaction has become a better choice than vegetable oils, as it could provide high yield of biodiesel without any compromise to food supply and other resources. In this study, FA from early stage of food waste liquefaction was extracted and tested for use as feedstock for biodiesel synthesis. The raw material was not pretreated but extraction was done by dry and wet methods. It was found that wet method could minimized the lost of short and medium-chained FA as well as reducing the number of steps required, thus, yielding higher amount of FA as feedstock. The effects of mixing, methanol ratio, reaction time and catalyst content were investigated for the acid-catalyzed esterification. The maximum biodiesel conversion obtained was 97.4 %.     

Evaluation of the giant reed (Arundo donax) in horizontal subsurface flow wetlands for the treatment of dairy processing factory wastewater

Two emergent macrophytes, Arundo donax and Phragmites australis, were established in experimental horizontal subsurface flow (HSSF), gravel-based constructed wetlands (CWs) and challenged by treated dairy processing factory wastewater with a median electrical conductivity of 8.9 mS cm(-1). The hydraulic loading rate was tested at 3.75 cm day(-1). In general, the plants grew well during the 7-month study period, with no obvious signs of salt stress. The major water quality parameters monitored (biological oxygen demand (BOD), suspended solids (SS) and total nitrogen (TN) but not total phosphorus) were generally improved after the effluent had passed through the CWs. There was no significance different in removal efficiencies between the planted beds and unplanted gravel beds (p?>?0.007), nor was there any significant difference in removal efficiencies between the A. donax and P. australis beds for most parameters. BOD, SS and TN removal in the A. donax and P. australis CWs was 69, 95 and 26 % and 62, 97 and 26 %, respectively. Bacterial removal was observed but only to levels that would allow reuse of the effluent for use on non-food crops under Victorian state regulations. As expected, the A. donax CWs produced considerably more biomass (37?±?7.2 kg wet weight) than the P. australis CWs (11?±?1.4 kg wet weight). This standing crop equates to approximately 179 and 68 tonnes ha(-1) year(-1) biomass (dry weight) for A. donax and P. australis, respectively (assuming a 250-day growing season and single-cut harvest). The performance similarity of the A. donax and P. australis planted CWs indicates that either may be used in HSSF wetlands treating dairy factory wastewater, although the planting of A. donax provides additional opportunities for secondary income streams through utilisation of the biomass produced.