Bera Lake is the largest natural fresh water reservoir in Malaysia. It has vital environmental and ecological importance for human and wild life. Nevertheless, water quality of this lake has been degraded during the last few decades due to land development projects at catchment area. Therefore, a comprehensive water quality assessment of Bera Lake was implemented in order to compare current water quality with the implementation of land development projects. In situ water quality surveying was implemented using calibrated full option Hydrolab DS 5. Eleven parameters viz., temperature, depth of sampling, salinity, Turbidity, total dried solid, pH, NH4(+), N03(-), Cl(-), saturation percentage of dissolved oxygen, specific conductivity were recorded in fifty one stations at 0.2h, 0.5h, and 0.8h depth. National Water Quality Standards for Malaysia (NWQS) and Water Quality were used to evaluate Bera Lake quality based on previous and resultant data. Vertical water quality analysis revealed a clear stratification in Bera Lake water profile in terms of temperature, dissolved oxygen, chloride (Cl(-)), nitrate (NO(3)), pH and specific conductivity (EC) parameters. Results clearly demonstrate the important role of land use changes since 1972 in the physico-chemical condition of water quality at Bera Lake. Classifications of water quality before and after land development project were calculated as class II and class V, respectively. A long-term and comprehensive monitoring of water quality assessment is recommended in order to reach plan of sustainable water resources use with conservation approach.
We report the use of a new precursor as active agents to promote the growth of carbon nanotubes (CNT) in methane ambient using a simple thermal chemical vapour deposition method. The agents consist of ammonia and methanol mixed at different ratios and was found to enhance the growth of CNTs. The optimum methanol to ammonia ratio was found to be 8 to 5, whereby longer and denser CNTs were produced compared to other ratios. The result was found otherwise when the experiment was done solely in methane ambient. In addition, CNT growth on substrates coated with double layer Ni catalyst was improved in terms of quality and density compared to a single coated substrates. This finding is supported by Raman spectrometry analysis.
A laboratory scale test rig to treat simulated flue gas using electron beam technology was installed at the Alurtron EB-Irradiation Center, MINT. The experiment test rig was proposed as a result of feasibility studies conducted jointly by IAEA, MINT and TNB Research in 1997. The test rig system consists of several components, among others, diesel generator sets, pipe ducts, spray cooler, ammonia dosage system, irradiation vessel, bag filter and gas analyzers. The installation was completed and commissioned in October 2001. Results from the commissioning test runs and subsequent experimental work showed that the efficiency of flue gas treatment is high. It was proven that electron beam technology might be applied in the treatment of air pollutants. This paper describes the design and work function of the individual major components as well as the full system function. Results from the initial experimental works are also presented.
Keberkesanan rawatan air sisa industri automotif ditentukan dengan menggunakan kaedah penjerapan turus. Peratusan penyingkiran ammonia dan logam berat terpilih telah dikaji menggunakan pasir biasa dan pasir terubah suai secara kimia sebagai bahan penjerap. Dua model matematik iaitu Model Thomas serta Model Yoon-Nelson telah digunakan untuk menentukan kapasiti penjerapan maksimum ammonia. Peratusan penyingkiran ammonia menunjukkan pasir terubah suai secara kimia mencatatkan julat peratusan penyingkiran yang lebih tinggi iaitu 43.68% hingga 96.55% berbanding pasir biasa yang mencatatkan julat 0% hingga 89.66%. Logam berat zink, mangan, kromium, kuprum, arsenik, nikel, kobalt dan ferum mencatatkan peratusan penyingkiran antara 93% hingga 100% apabila menggunakan pasir terubah suai secara kimia manakala pasir biasa mencatatkan julat peratusan penyingkiran daripada 0.8% hingga 100%. Keputusan analisis menggunakan Model Thomas menunjukkan kapasiti penjerapan maksimum, qo ammonia menggunakan pasir terubah suai secara kimia (8.80 mg/g) adalah empat kali lebih tinggi daripada pasir biasa (2.57 mg/g) manakala masa bolos, t0.5 bahan penjerap yang ditentukan menggunakan Model Yoon dan Nelson mencatatkan masa tertinggi bagi pasir terubah suai secara kimia iaitu 30.18 min berbanding 9.57 min bagi pasir biasa. Kajian ini menunjukkan peratusan penyingkiran dan kapasiti penjerapan ammonia dan logam berat terpilih iaitu zink, mangan, kuprum, arsenik, nikel, kobalt dan ferum lebih tinggi bagi turus pasir terubah suai secara kimia berbanding pasir biasa.
Ozonation, combined with the Fenton process (O(3)/H(2)O(2)/Fe(2+)), was used to treat matured landfill leachate. The effectiveness of the Fenton molar ratio, Fenton concentration, pH variance, and reaction time were evaluated under optimum operational conditions. The optimum removal values of chemical oxygen demand (COD), color, and NH(3)-N were found to be 65%, 98%, and 12%, respectively, for 90 min of ozonation using a Fenton molar ratio of 1 at a Fenton concentration of 0.05 mol L(-1) (1700 mg/L) H(2)O(2) and 0.05 mol L(-1) (2800 mg/L) Fe(2+) at pH 7. The maximum removal of NH(3)-N was 19% at 150 min. The ozone consumption for COD removal was 0.63 kg O(3)/kg COD. To evaluate the effectiveness, the results obtained in the treatment of stabilized leachate were compared with those obtained from other treatment processes, such as ozone alone, Fenton reaction alone, as well as combined Fenton and ozone. The combined method (i.e., O(3)/H(2)O(2)/Fe(2+)) achieved higher removal efficiencies for COD, color, and NH(3)-N compared with other studied applications.
Industrial, and municipal wastes are part of the main sources of environmental hazards as well as groundwater and surface water pollutions. If not well composed, treated, and safely disposed, it could permeate through the subsurface lithologies by reaching down to the underground water aquifers, particularly in zones of unprotected aquifer units. Pollutants, most especially the landfills leachates that encompassed organic contaminants, ammonia, nitrates, total nitrogen, suspended solids, heavy metals and soluble inorganic salts, i.e., soluble nitrogen, sulphur compound, sulphate and chlorides, could posed undesirable environmental impacts due to inappropriate disposals that may give rise to gaseous fumes and leachate formations. An electrical resistivity geophysical technique utilizing the RES2D no-invasive, cost-effective and rapid method of data collection was integrated with the 3D Oasis Montaj software to approximate the volume of the generated rectangular prism model of the contaminants delineated from mixtures of the industrial, and municipal wastes plumes to be 312,000 m 3.
The objective of this study was to investigate the performance of employing Fenton's reagent in the advanced oxidation of ozone to treat stabilized landfill leachate in an ozone reactor. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as ozone and Fenton dosage, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following four responses proved to be significant with very low probabilities (<0.0001): chemical oxygen demand (COD), color, NH-N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 90 min, 30 g/m³ ozone, 0.01 mol/L₂H₂O,0.02 mol/L Fe²⁺, and pH 5. COD, color, and NH₃-N removal rates of 79%, 100%, and 20%, respectively, and 0.18 kg O₃/kg COD OC were obtained. The predictions correspond well with experimental results (COD, color, and NH-N removal rates of 78%, 98.5%, and 19%, respectively, and 0.29 kg O₃/kg COD OC). This method reduces the treatment time and improves the treatment efficiency relative to a previously published method that used Fenton's reagent prior to ozonation.
With inoculum sludge from a conventional activated sludge wastewater treatment plant, three sequencing batch reactors (SBRs) fed with synthetic wastewater were operated at different high temperatures (30, 40 and 50±1°C) to study the formation of aerobic granular sludge (AGS) for simultaneous organics and nutrients removal with a complete cycle time of 3h. The AGS were successfully cultivated with influent loading rate of 1.6CODg(Ld)(-1). The COD/N ratio of the influent wastewater was 8. The results revealed that granules developed at 50°C have the highest average diameter, (3.36mm) with 98.17%, 94.45% and 72.46% removal efficiency observed in the system for COD, ammonia and phosphate, respectively. This study also demonstrated the capabilities of AGS formation at high temperatures which is suitable to be applied for hot climate conditions.
The effect of temperature on the efficiency of organics and nutrients removal during the cultivation of aerobic granular sludge (AGS) in biological treatment of synthetic wastewater was studied. With this aim, three 3 L sequencing batch reactors (SBRs) with influent loading rate of 1.6 COD g (L d)(-1) were operated at different high temperatures (30, 40 and 50 °C) for simultaneous COD, phosphate and ammonia removal at a complete cycle time of 3 h. The systems were successfully started up and progressed to steady state at different cultivation periods. The statistical comparison of COD, phosphate and ammonia for effluent from the three SBRs revealed that there was a significant difference between groups of all the working temperatures of the bioreactors. The AGS cultivated at different high temperatures also positively correlated with the accumulation of elements including carbon, oxygen, phosphorus, silicon, iron, aluminium, calcium and magnesium that played important roles in the granulation process.
Exposure to TEX-OE®, a patented extract of the prickly pear cactus (Opuntia ficus indica) containing chaperone-stimulating factor, was shown to protect common carp, Cyprinus carpio L., fingerlings against acute ammonia stress. Survival was enhanced twofold from 50% to 95% after exposure to 5.92 mg L(-1) NH(3) , a level determined in the ammonia challenge bioassay as the 1-h LD50 concentration for this species. Survival of TEX-OE®-pre-exposed fish was enhanced by 20% over non-exposed controls during lethal ammonia challenge (14.21 mg L(-1) NH(3) ). Increase in the levels of gill and muscle Hsp70 was evident in TEX-OE®-pre-exposed fish but not in the unexposed controls, indicating that application of TEX-OE® accelerated carp endogenous Hsp70 synthesis during ammonia perturbation. Protection against ammonia was correlated with Hsp70 accretion.
The initial rate of NH(3)/NH(4)(+) accumulation in a medium containing L(3) Teladorsagia circumcincta was 0.18-0.6 pmol h(-1) larva(-1), which increased linearly with larval density. However it appeared that the larva-generated external concentration of NH(3)/NH(4)(+) did not exceed about 130 μM. The rate of NH(3)/NH(4)(+) accumulation increased with temperature between 4 °C and 37 °C, declined with increasing pH or increasing external NH(3)/NH(4)(+) concentration and was not significantly affected by the concentration of the phosphate buffer or by exsheathing the larvae. We infer from these data that the efflux of NH(3)/NH(4)(+) is a diffusive process and that the secreted or excreted NH(3)/NH(4)(+) is generated enzymatically rather than dissociating from the surface of the nematode. The enzymatic source of the NH(3)/NH(4)(+) is yet to be identified. Since the concentration of NH(3)/NH(4)(+) in the rumen and abomasum is higher than 130 μM, it is unlikely that T. circumcincta contributes to it, but NH(3)/NH(4)(+) may be accumulated from the rumen fluid by the nematode.
Like other nematodes, both L(3) and adult Teladosagia circumcincta secrete or excrete NH(3)/NH(4)(+), but the reactions involved in the production are unclear. Glutamate dehydrogenase is a significant source NH(3)/NH(4)(+) in some species, but previous reports indicate that the enzyme is absent from L(3)Haemonchus contortus. We show that glutamate dehydrogenase was active in both L(3) and adult T. circumcincta. The apparent K(m)s of the L(3) enzyme differed from those of the adult enzyme, the most significant of these being the increase in the K(m) for NH(4)(+) from 18mM in L(3) to 49mM in adults. The apparent V(max) of the oxidative deamination reaction was greater than that of the reductive reaction in L(3), but this was reversed in adults. The activity of the oxidative reaction of the L(3) enzyme was not affected by adenine nucleotides, but that of the reductive reaction was stimulated significantly by either ADP or ATP. The L(3) enzyme was more active with NAD(+) than it was with NADP(+), although the activities supported by NADH and NADPH were similar at saturating concentrations. While the activity of the oxidative reaction was sufficient to account for the NH(3)/NH(4)(+) efflux we have previously reported, the reductive amination reaction was likely to be more active.
The cell-free extract of locally isolated Rhodococcus UKMP-5M strain was used as an alternative to develop greener and cost effective cyanide removal technology. The present study aims to assess the viability of the cell-free extract to detoxify high concentrations of cyanide which is measured through the monitoring of protein concentration and specific cyanide-degrading activity. When cyanide-grown cells were subjected to grinding in liquid nitrogen which is relatively an inexpressive and fast cell disruption method, highest cyanide-degrading activity of 0.63 mM min(-1) mg(-1) protein was obtained in comparison to enzymatic lysis and agitation with fine glass beads. The cell-free extracts managed to degrade 80% of 20 mM KCN within 80 min and the rate of cyanide consumption increased linearly as the concentration of protein was raised. In both cases, the addition of co-factor was not required which proved to be advantageous economically. The successful formation of ammonia and formate as endproducts indicated that the degradation of cyanide by Rhodococcus UKMP-5M proceeded via the activity of cyanidase and the resulting non-toxic products are safe for disposal into the environment. Further verification with SDS-PAGE revealed that the molecular weight of the active enzyme was estimated to be 38 kDa, which is consistent with previously reported cyanidases. Thus, the utilization of cell-free extracts as an alternative to live microbial in cyanide degradation offers numerous advantageous such as the potential to tolerate and degrade higher concentration of cyanide and total reduction in the overall cost of operation since the requirement for nutrient support is irrelevant.
A Rhodococcus sp. UKMP-5M isolate was shown to detoxify cyanide successfully, suggesting the presence of an intrinsic property in the bacterium which required no prior cyanide exposure for induction of this property. However, in order to promote growth, Rhodococcus sp. UKMP-5M was fully acclimatized to cyanide after 7 successive subcultures in 0.1 mM KCN for 30 days. To further shorten the lag phase and simultaneously increase the tolerance towards higher cyanide concentrations, the bacterium was induced with various nitrile compounds sharing a similar degradatory pathway to cyanide. Acetonitrile emerged as the most favored inducer and the induced cells were able to degrade 0.1 mM KCN almost completely within 18 h. With the addition of subsequent aliquots of 0.1 mM KCN a shorter period for complete removal of cyanide was required, which proved to be advantageous economically. Both resting cells and crude enzyme of Rhodococcus sp. UKMP-5M were able to biodegrade cyanide to ammonia and formate without the formation of formamide, implying the identification of a simple hydrolytic cyanide degradation pathway involving the enzyme cyanidase. Further verification with SDS-PAGE revealed that the molecular weight of the active enzyme was estimated to be 38 kDa, which is consistent with previously reported cyanidases. Since the recent advancement in the application of biological methods in treating cyanide-bearing wastewater has been promising, the discovery of this new bacterium will add value by diversifying the existing microbial populations capable of cyanide detoxification.
As an indispensable energy source, ammonia plays an essential role in agriculture and various industries. Given that the current ammonia production is still dominated by the energy-intensive and high carbon footprint Haber-Bosch process, photocatalytic nitrogen fixation represents a low-energy consuming and sustainable approach to generate ammonia. Heterostructured photocatalysts are hybrid materials composed of semiconductor materials containing interfaces that make full use of the unique superiorities of the constituents and synergistic effects between them. These promising photocatalysts have superior performances and substantial potential in photocatalytic reduction of nitrogen. In this review, a wide spectrum of recently developed heterostructured photocatalysts for nitrogen fixation to ammonia are evaluated. The fundamentals of solar-to-ammonia conversion, basic principles of various heterojunction photocatalysts and modification strategies are systematically reviewed. Finally, a brief summary and perspectives on the ongoing challenges and directions for future development of nitrogen photofixation catalysts are also provided.
Here, we present the first complete genome sequence of Serratia fonticola DSM 4576(T), a potential plant growth promoting (PGP) bacterium which confers solubilization of inorganic phosphate, indole-3-acetic acid production, hydrogen cyanideproduction, siderophore production and assimilation of ammonia through the glutamate synthase (GS/GOGAT) pathway. This genome sequence is valuable for functional genomics and ecological studies which are related to PGP and biocontrol activities.
Neuronal excitation, involving the excitatory glutamate receptors, is recognized as an important underlying mechanism in neurodegenerative disorders. To understand their role in excitotoxicity, the nitric oxide synthase (NOS), argininosuccinate synthetase (AS), argininosuccinate lyase (AL), glutamine synthetase (GS), and arginase activities, along with the concentration of nitrate/nitrite, thiobarbituric acid-reactive substances (TBARS), and total antioxidant status (TAS), were estimated in the cerebral cortex, cerebellum, and brain stem of rats subjected to kainic acid-mediated excitotoxicity. The results of this study clearly demonstrated the increased production of NO by increased activity of NOS. The increased activities of AS and AL suggest the increased and effective recycling of citrulline to arginine in excitotoxicity, making NO production more effective and contributing to its toxic effects. The decreased activity of GS may favor the prolonged availability of glutamic acid, causing excitotoxicity, leading to neuronal damage. The increased formation of TBARS and decreased TAS indicate the presence of oxidative stress in excitotoxicity.
Nitric oxide is postulated to be involved in the pathophysiology of neurological disorders due to hypoxia/ anoxia in brain due to increased release of glutamate and activation of N-methyl-D-aspartate receptors. Reactive oxygen species have been implicated in pathophysiology of many neurological disorders and in brain function. To understand their role in anoxia (hypobaric hypoxia) and reperfusion (reoxygenation), the nitric oxide synthase, argininosuccinate synthetase, argininosuccinate lyase, glutamine synthetase and arginase activities along with the concentration of nitrate /nitrite, thiobarbituric acid reactive substances and total antioxidant status were estimated in cerebral cortex, cerebellum and brain stem of rats subjected to anoxia and reperfusion. The results of this study clearly demonstrated the increased production of nitric oxide by increased activity of nitric oxide synthase. The increased activities of argininosuccinate synthetase and argininosuccinate lyase suggest the increased and effective recycling of citrulline to arginine in anoxia, making nitric oxide production more effective and contributing to its toxic effects. The decreased activity of glutamine synthetase may favor the prolonged availability of glutamic acid causing excitotoxicity leading to neuronal damage in anoxia. The increased formation of thiobarbituric acid reactive substances and decreased total antioxidant status indicate the presence of oxidative stress in anoxia and reperfusion. The increased arginase and sustained decrease of GS activity in reperfusion group likely to be protective.
Fluxes and composition dynamics of atmospheric nitrogen deposition play key roles in better balancing economic development and ecological environment. However, there are some knowledge gaps and difficulties in urban ecosystems, especially for small and medium-sized cities. In this study, both flux and composition (ratio of NH4+-N to NO3--N, RN) of wet-deposited dissolved inorganic nitrogen (DIN, sum of NO3--N and NH4+-N) were estimated and sources were identified at a long-term urban observation station in Tongling, a typical medium-sized city in eastern China during 2010-2016, respectively. Results showed that wet-deposited DIN fluxes were 33.20 and 28.15 kgN ha-1 yr-1 in Tongling city during 2010-2011 and 2015-2016, respectively. Compared to these two periods, both DIN and NO3--N fluxes decreased by 15.2% and 31.8% for a series of NOx abatement measures applied effectively, respectively. At the same time, the NH4+-N flux remained stable and ranged from 19.53 to 20.62 kgN ha-1 yr-1, and the RN increased from 1.7 to 2.2. Seasonally, winds from the southwest and west-southwest with higher frequencies and speeds in spring and summer brought more NH4+-N and DIN wet deposition from an ammonia plant, which could threaten the safety of regional hydrosphere ecosystems. On the whole, the wet-deposited NH4+-N was threatening regional ecosystems of both the hydrosphere and forest. The wet-deposited DIN including NH4+-N in Tongling city stemmed mainly from a combined source of coal combustion and dust from Cu extraction and smelting, ammonia production, and roads. Therefore, production lines should be updated for Cu extraction and smelting industries, thermal power generations and the ammonia plant, old vehicles should be eliminated, and the use of new energy vehicles should be promoted for regional sustainable development and human health in the medium-sized city.