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.
The objective of this study was to investigate the performance of employing persulfate 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 persulfate dosages, 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): COD, color, NH3-N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 210 min, 30 g/m(3) ozone, 1g/1g COD0/S2O8(2-) ratio, and pH 10. The experimental results were corresponded well with predicted models (COD, color, and NH3-N removal rates of 72%, 96%, and 76%, respectively, and 0.60 (kg O3/kg COD OC). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as ozone only and persulfate S2O8(2-) only, to evaluate its effectiveness. The combined method (i.e., O3/S2O8(2-)) achieved higher removal efficiencies for COD, color, and NH3-N compared with other studied applications. Furthermore, the new method is more efficient than ozone/Fenton in advanced oxidation process in the treatment of the same studied leachate.
Untreated landfill leachate can harm the environment and human health due to its organic debris, heavy metals, and nitrogen molecules like ammonia. Microbial fuel cells (MFCs) have emerged as a promising technology for treating landfill leachate and generating energy. However, high concentrations of total ammonia-nitrogen (TAN), which includes both ammonia and the ammonium ion, can impede MFC performance. Therefore, maintaining an adequate TAN concentration is crucial, as both excess and insufficient levels can reduce power generation. To evaluate the worldwide research on MFCs using landfill leachate as a substrate, bibliometric analysis was conducted to assess publication output, author-country co-authorship, and author keyword co-occurrence. Scopus and Web of Science retrieved 98 journal articles on this topic during 2011-2022; 18 were specifically evaluated and analysed for MFC ammonia inhibition. The results showed that research on MFC using landfill leachate as a substrate began in 2011, and the number of related papers has consistently increased every 2 years, totaling 4060 references. China, India, and the USA accounted for approximately 60% of all global publications, while the remaining 40% was contributed by 70 other countries/territories. Chongqing University emerged as one of the top contributors among this subject's ten most productive universities. Most studies found that maintaining TAN concentrations in the 400-800 mg L-1 in MFC operation produced good power density, pollution elimination, and microbial acclimatization. However, the database has few articles on MFC and landfill leachate; MFC ammonia inhibition remains the main factor impacting system performance. This bibliographic analysis provides excellent references and future research directions, highlighting the current limitations of MFC research in this area.
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.
The anaerobic treatment of leachate from a municipal waste transfer station in Malaysia was tested using a pilot scale anaerobic biofilm digester system that was operated under HRT sequence of 30-day, 25-day, 20-day and 10-day for 163 days under mesophilic conditions. Despite the leachate's complex characteristics, the system showed great performance given its maximum COD, BOD5 and total phosphorus removal efficiencies of 98 ± 1%, 99 ± 1% and 92 ± 9% respectively. The system was stable throughout its operation and showed optimal average values for the monitored parameters such as pH (7.53 ± 0.14), total VFA (79 ± 66 mg HOAc/L), alkalinity (10,919 ± 1556 mg CaCO3/L) and a non-toxic value for accumulated ammonia (960 ± 106 mg NH3-N/L). Measurement of the average daily biogas production yielded a value of 25 ± 1 m3/day throughout the system's operation with a composition of 57 ± 12% methane and 26 ± 6% carbon dioxide.
The fluctuation of domestic wastewater characteristic inhibits the current conventional microbial-based treatment. The bioremediation fungi has received attention and reported to be an effective alternative to treat industrial wastewater. Similar efficient performance is envisaged for domestic wastewater whereby assessed performance of fungi for varying carbon-to-nitrogen ratios in domestic wastewater is crucial. Thus, the performance of pre-grown wild-Serbian Ganoderma lucidum mycelial pellets (GLMPs) was evaluated on four different synthetic domestic wastewaters under different conditions of initial pH (pH 4, 5, and 7) and chemical oxygen demand (COD) to nitrogen (COD/N) ratio of 3.6:1, 7.1:1, 14.2:1, and 17.8:1 (C3.6N1, C7.1N1, C14.2N1, and C17.8N1). The COD/N ratios with a constant concentration of ammonia-nitrogen (NH3-N) were chosen on the basis of the urban domestic wastewater characteristics sampled at the inlet basin of a sewage treatment plant (STP). The parameters of pH, COD, and NH3-N were measured periodically during the experiment. The wild-Serbian GLMPs efficiently removed the pollutants from the synthetic sewage. The COD/N ratio of C17.8N1 wastewater had the best COD and NH3-N removal, as compared to the lower COD/N ratio, and the shortest treatment time was obtained in an acidic environment at pH 4. The highest percentage for COD and NH3-N removal achieved was 96.0% and 93.2%, respectively. The results proved that the mycelium of GLMP has high potential in treating domestic wastewater, particularly at high organic content as a naturally sustainable bioremediation system.
A split plot 3 × 3 experiment was designed to examine the impact of three concentrations of CO₂ (400, 800 and 1,200 μmol·mol⁻¹) on the phenolic and flavonoid compound profiles, phenylalanine ammonia lyase (PAL) and antioxidant activity in three varieties of Labisia pumila Benth. (var. alata, pumila and lanceolata) after 15 weeks of exposure. HPLC analysis revealed a strong influence of increased CO₂ concentration on the modification of phenolic and flavonoid profiles, whose intensity depended on the interaction between CO₂ levels and L. pumila varieties. Gallic acid and quercetin were the most abundant phenolics and flavonoids commonly present in all the varieties. With elevated CO₂ (1,200 μmol·mol⁻¹) exposure, gallic acid increased tremendously, especially in var. alata and pumila (101-111%), whilst a large quercetin increase was noted in var. lanceolata (260%), followed closely by alata (201%). Kaempferol, although detected under ambient CO₂ conditions, was undetected in all varieties after exposure. Instead, caffeic acid was enhanced tremendously in var. alata (338~1,100%) and pumila (298~433%). Meanwhile, pyragallol and rutin were only seen in var. alata (810 μg·g⁻¹ DW) and pumila (25 μg·g⁻¹ DW), respectively, under ambient conditions; but the former compound went undetected in all varieties while rutin continued to increase by 262% after CO₂ enrichment. Interestingly, naringenin that was present in all varieties under ambient conditions went undetected under enrichment, except for var. pumila where it was enhanced by 1,100%. PAL activity, DPPH and FRAP also increased with increasing CO₂ levels implying the possible improvement of health-promoting quality of Malaysian L. pumila under high CO₂ enrichment conditions.
The present study investigated the use of modified titanium dioxide (TiO2) based photocatalytic degradation (PCD) process for the removal of some critical charged aqueous phase pollutants. First of all, the use of Nafion TiO2 (Nf-TiO2) and silica TiO2 (Si-TiO2) for the removal of aqueous phase ammonia (NH4+/NH3) species employing near UV lamp as energy source was studied. The use of Nf-TiO2 enhanced NH4+/NH3 PCD with optimum removal noted for 1 mL of Nafion solution coating per g of TiO2 and respective overall NH4+/NH3 removal was about 1.7 times higher compared to plain TiO2 at 6 h reaction time. Similarly the 0.5 mL silica solution coating per g TiO2 sample, also enhanced NH4+/NH3 removal with optimum efficiency similar to Nf-TiO2. The results from effect of ammonia concentration on to its PCD using Nf-TiO2 indicated that overall mass based NH4+/NH3 removal was higher at greater NH4+/NH3 amounts indicating high efficiency of Nf-TiO2. Similar trends were noted for Si-TiO2 as well. Furthermore, the results from modified TiO2 and mixed NH4+/NH3 and cyanide (CN-) systems indicated successful removal of co-pollutant CN- along with simultaneous degradation of NH4+/NH3 species at rates that were still higher than plain TiO2. Nevertheless application of Nf-TiO2 for the treatment of cationic dye methylene blue (MB) indicated slower MB removal compared to plain TiO2 though significant MB degradation using Nf-TiO2 could still be achieved at pH3. Additionally the results from solar radiation energized PCD process indicated positive role of solar radiation for the removal of NH4+/NH3 species under a varying set of conditions.
The purpose of the present study was to examine the removal of ammoniacal nitrogen (NH4-N) from synthetic wastewater using limestone (LS) and granular activated carbon (GAC) mixture as low cost adsorbent. In batch study, optimum shaking and settling times were 150 and 120 min, respectively. The LS-GAC mixture ratio of 25:15 removed about 58% NH4-N. The smaller particle size of medium yielded higher adsorption capacity. The equilibrium adsorption data followed the Freundlich isotherm (R2 > 0.98) but it showed weak bond. Adsorption kinetics were well described by the pseudo second-order rate model (R2 > 0.93). The upflow column showed that higher flow rate and initial concentration resulted in shorter column saturation time. The study showed that the usage of GAC could be reduced by combining GAC with LS for the removal of NH4-N from wastewater; thus reducing the cost of treatment.
Air pollution can be detected through rainwater composition. In this study, long-term measurements (2000-2014) of wet deposition were made to evaluate the physicochemical interaction and the potential sources of pollution due to changes of land use. The rainwater samples were obtained from an urban site in Kuala Lumpur and a highland-rural site in the middle of Peninsular Malaysia. The compositions of rainwater were obtained from the Malaysian Meteorological Department. The results showed that the urban site experienced more acidity in rainwater (avg=277mm, range of 13.8 to 841mm; pH=4.37) than the rural background site (avg=245mm, range of 2.90 to 598mm; pH=4.97) due to higher anthropogenic input of acid precursors. The enrichment factor (EF) analysis showed that at both sites, SO42-, Ca2+ and K+ were less sensitive to seawater but were greatly influenced by soil dust. NH4+ and Ca2+ can neutralise a larger fraction of the available acid ions in the rainwater at the urban and rural background sites. However, acidifying potential was dominant at urban site compared to rural site. Source-receptor relationship via positive matrix factorisation (PMF 5.0) revealed four similar major sources at both sites with a large variation of the contribution proportions. For urban, the major sources influence on the rainwater chemistry were in the order of secondary nitrates and sulfates>ammonium-rich/agricultural farming>soil components>marine sea salt and biomass burning, while at the background site the order was secondary nitrates and sulfates>marine sea salt and biomass burning=soil components>ammonia-rich/agricultural farming. The long-term trend showed that anthropogenic activities and land use changes have greatly altered the rainwater compositions in the urban environment while the seasonality strongly affected the contribution of sources in the background environment.
Determining the water quality of Bakun Reservoir 13 months after it operates at full supply level is crucial for better understanding of changes in the physicochemical parameters, which may enable the prediction of its effects on the survival of aquatic life in the reservoir. This study determined 13 physicochemical parameters at six stations within the reservoir at fixed depths. The results showed that the minimum 5 mg/L of dissolved oxygen (DO) required for sensitive aquatic organisms was recorded at 6 m depth. However, DO was not detectable at depths exceeding 7 m. The water was acidic at depths of more than 10 m. Turbidity and total suspended solids increased corresponding with depth. Inorganic nitrogen were predominantly in the form of ammonia-nitrogen, creating an unhealthy environment for aquatic life. Concentration of Chl-a was significantly higher at the subsurface water than 30 m depth in four out of six stations. The present study shows changes in water quality as compared to the pre-impounded period and 15 months after the filling phase, in particular, stratification of dissolved oxygen, thermocline conditions and alkalinity. The changes varied according to the distance from the dam and may have been influenced by existing land developments within the area such as the construction of the Murum Hydroelectric Dam, oil palm plantations and timber concessionares. Though the water quality might have deteriorated, further study is needed to determine if this condition will prolong.
Saffron (Crocus sativus L.) is an important plant in medicine. The Kashmir Valley (J&K, India) is one of the world's largest and finest saffron producing regions. However, over the past decade, there has been a strong declining trend in saffron production in this area. Plant Growth Promoting Rhizobacteria (PGPR) are free living soil bacteria that have ability to colonize the surfaces of the roots and ability to boost plant growth and development either directly or indirectly. Using the efficient PGPR as a bio-inoculant is another sustainable agricultural practice to improve soil health, grain yield quality, and biodiversity conservation. In the present study, a total of 13 bacterial strains were isolated from rhizospheric soil of saffron during the flowering stage of the tubers and were evaluated for various plant growth promoting characteristics under in vitro conditions such as the solubilization of phosphate, production of indole acetic acid, siderophore, hydrocyanic acid, and ammonia production and antagonism by dual culture test against Sclerotium rolfsii and Fusarium oxysporum. All the isolates were further tested for the production of hydrolytic enzymes such as protease, lipase, amylase, cellulase, and chitinase. The maximum proportions of bacterial isolates were gram-negative bacilli. About 77% of the bacterial isolates showed IAA production, 46% exhibited phosphate solubilization, 46% siderophore, 61% HCN, 100% ammonia production, 69% isolates showed protease activity, 62% lipase, 46% amylase, 85% cellulase, and 39% showed chitinase activity. Three isolates viz., AIS-3, AIS-8 and AIS-10 were found to have the most plant growth properties and effectively control the growth of Sclerotium rolfsii and Fusarium oxysporum. The bacterial isolates were identified as Brevibacterium frigoritolerans (AIS-3), Alcaligenes faecalis subsp. Phenolicus (AIS-8) and Bacillus aryabhattai (AIS-10) respectively by 16S rRNA sequence analysis. Therefore, these isolated rhizobacterial strains could be a promising source of plant growth stimulants to increase cormlets growth and increase saffron production.
Black pepper production in Malaysia was restricted by various diseases. Hazardous chemical products appear to be the best solution to control diseases in black pepper cultivation. However, persistence of chemical residues in peppercorns could affect the quality of exports and consumptions. Application of fertilizers is crucial to sustain pepper growth and high yield. But, continuous use of chemical fertilizers could affect the soil ecosystem and eventually restrict nutrient uptake by pepper roots. Therefore, we propose biological approaches as an alternative solution instead of chemical products to sustain pepper cultivation in Malaysia. In this study, we have isolated a total of seven indigenous rhizobacteria antagonistic to soil-borne Fusarium solani, the causal fungus of slow decline, the most serious debilitating disease of black pepper in Malaysia. The isolated bacteria were identified as Bacillus subtilis, Bacillus siamensis, Brevibacillus gelatini, Pseudomonas geniculata, Pseudomonas beteli, Burkholderia ubonensis and Burkholderia territorii. These bacteria were effective in production of antifungal siderophore with the amount of 53.4 %-73.5 % per 0.5 mL of cell-free supernatants. The bacteria also produced appreciable amount of chitinase with chitinolytic index was ranged from 1.19 to 1.76. The bacteria have shown phosphate solubilizing index within 1.61 to 2.01. They were also efficient in ACC deaminase (0.52 mM-0.62 mM) and ammonia (60.3 mM-75.3 mM) production. The isolated antagonists were efficacious in stimulation of black pepper plant growth and root development through IAA (10.5 μg/mL-42.6 μg/mL) secretion. In conclusion, the isolated rhizobacteria are potent to be developed not only as biocontrol agents to minimize the utilization of hazardous chemicals in black pepper disease management, but also developed as bio-fertilizers to improve black pepper plant growth due to their capabilities in plant growth-promotion.
The objective of this study was to determine the effects of feeding on the excretory nitrogen (N) metabolism of the giant mudskipper, Periophthalmodon schlosseri, with special emphasis on the role of urea synthesis in ammonia detoxification. The ammonia and urea excretion rates of P. schlosseri increased 1.70- and 1.92-fold, respectively, within the first 3 h after feeding on guppies. Simultaneously, there were significant decreases in ammonia levels in the plasma and the brain, and in urea contents in the muscle and liver, of P. schlosseri at 3 h post-feeding. Thus, it can be concluded that P. schlosseri was capable of unloading ammonia originally present in some of its tissues in anticipation of ammonia released from the catabolism of excess amino acids after feeding. Subsequently, there were significant increases in urea content in the muscle, liver and plasma (1.39-, 2.17- and 1.62-fold, respectively) at 6 h post-feeding, and the rate of urea synthesis apparently increased 5.8-fold between 3 h and 6 h. Increased urea synthesis might have occurred in the liver of P. schlosseri because the greatest increase in urea content was observed therein. The excess urea accumulated in the body at 6 h was completely excreted between 6 and 12 h, and the percentage of waste-N excreted as urea-N increased significantly to 26% during this period, but never exceeded 50%, the criterion for ureotely, meaning that P. schlosseri remained ammonotelic after feeding. By 24 h, 62.7% of the N ingested by P. schlosseri was excreted, out of which 22.6% was excreted as urea-N. This is the first report on the involvement of increased urea synthesis and excretion in defense against ammonia toxicity in the giant mudskipper, and our results suggest that an ample supply of energy resources, e.g. after feeding, is a prerequisite for the induction of urea synthesis. Together, increases in nitrogenous excretion and urea synthesis after feeding effectively prevented a postprandial surge of ammonia in the plasma of P. schlosseri as reported previously for other fish species. Consequently, contrary to previous reports, there were significant decreases in the ammonia content of the brain of P. schlosseri throughout the 24 h period post-feeding, accompanied by a significant decrease in brain glutamine content between 12 h and 24 h.
In this study, a sequential batch reactor (SBR) with different types of fibers was employed for the treatment of poultry slaughterhouse wastewater. Three types of fibers, namely, juite fiber (JF), bio-fringe fiber (BF), and siliconised conjugated polyester fiber (SCPF), were used. Four SBR experiments were conducted, using the fibers in different reactors, while the fourth reactor used a combination of these fibers. The treatment efficiency of the different reactors with and without fibers on biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonia-nitrogen (NH₃-N), phosphorus (P), nitrite (NO₂), nitrate (NO₃), total suspended solids (TSS), and oil-grease were evaluated. The removal efficiency for the reactors with fibers was higher than that of the reactor without fibers for all pollutants. The treated effluent had 40 mg/L BOD₅ and 45 mg/L COD with an average removal efficiency of 96% and 93%, respectively, which meet the discharge limits stated in the Environmental Quality Act in Malaysia.
Sequencing batch reactor (SBR) is one of the various methods of biological treatments used for treating wastewater and landfill leachate. This study investigated the treatment of landfill leachate and domestic wastewater by adding a new adsorbent (powdered ZELIAC; PZ) to the SBR technique. ZELIAC consists of zeolite, activated carbon, lime stone, rice husk ash, and Portland cement. The response surface methodology and central composite design were used to elucidate the nature of the response surface in the experimental design and describe the optimum conditions of the independent variables, including aeration rate (L/min), contact time (h), and ratio of leachate to wastewater mixture (%; v/v), as well as their responses (dependent variables). Appropriate conditions of operating variables were also optimized to predict the best value of responses. To perform an adequate analysis of the aerobic process, four dependent parameters, namely, chemical oxygen demand (COD), color, ammonia-nitrogen (NH3-N), and phenols, were measured as responses. The results indicated that the PZ-SBR showed higher performance in removing certain pollutants compared with SBR. Given the optimal conditions of aeration rate (1.74 L/min), leachate to wastewater ratio (20%), and contact time (10.31 h) for the PZ-SBR, the removal efficiencies for color, NH3-N, COD, and phenols were 84.11%, 99.01%, 72.84%, and 61.32%, respectively.
Food wastes with high moisture and organic matter content are likely to emit odours as a result of the decomposition process. The management of odour from decomposing wastes is needed to sustain the interest of residents and local councils in the source separation of kitchen wastes. This study investigated the potential of baking soda (at 50 g, 75 g and 100g per kg food waste) to control odour from seven days stored food waste. It was found that 50 g of baking soda, spread at the bottom of 8l food wastes bin, can reduce the odour by about 70%. A higher amount (above 100g) is not advised as a pH higher than 9.0 may be induced leading to the volatilization of odorous ammonia. This research finding is expected to benefit the waste management sector, food processing industries as well as the local authorities where malodour from waste storage is a pressing issue.
Removal of low-concentration ammonia (1-10 ppm) from aquaculture wastewater was investigated via polysulfone (PSf)/zeolite mixed matrix membrane. PSf/zeolite mixed matrix membranes with different weight ratios (90/10, 80/20, 70/30 and 60/40 wt.%) were prepared and characterized. Results indicate that PSf/zeolite (80/20) was the most efficient membrane for removal of low-concentration ammonia. The ammonia elimination by PSf/zeolite (80/20) from aqueous solution for 10, 7, 5, 3 and 1 ppm of ammonia was 100%, 99%, 98.8%, 96% and 95% respectively. The recorded results revealed that pure water flux declined in higher loading of zeolite in the membrane matrix due to surface pore blockage caused by zeolite particles. On the other hand, ammonia elimination from water was decreased in higher contents of zeolite because of formation of cavities and macrovoids in the membrane substructure.
This study evaluates the sugarcane bagasse derived activated carbon (SBAC) prepared by microwave heating for the adsorptive removal of ammonical nitrogen and orthophosphate from the semi-aerobic landfill leachate. The physical and chemical properties of SBAC were examined by pore structural analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. The effects of adsorbent dosage, contact time and solution pH on the adsorption performance were investigated in a batch mode study at 30°C. Equilibrium data were favorably described by the Langmuir isotherm model, with a maximum monolayer adsorption capacity for ammonical nitrogen and orthophosphate of 138.46 and 12.81 mg/g, respectively, while the adsorption kinetic was best fitted to the pseudo-second-order kinetic model. The results illustrated the potential of sugarcane bagasse derived activated carbon for the adsorptive treatment of semi-aerobic landfill leachate.
A randomized complete block design was used to characterize the relationship between production of total phenolics, flavonoids, ascorbic acid, carbohydrate content, leaf gas exchange, phenylalanine ammonia-lyase (PAL), soluble protein, invertase and antioxidant enzyme activities (ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD) in Labisia pumila Benth var. alata under four levels of potassium fertilization experiments (0, 90, 180 and 270 kg K/ha) conducted for 12 weeks. It was found that the production of total phenolics, flavonoids, ascorbic acid and carbohydrate content was affected by the interaction between potassium fertilization and plant parts. As the potassium fertilization levels increased from 0 to 270 kg K/ha, the production of soluble protein and PAL activity increased steadily. At the highest potassium fertilization (270 kg K/ha) L. pumila exhibited significantly higher net photosynthesis (A), stomatal conductance (g(s)), intercellular CO(2) (C(i)), apparent quantum yield (ξ) and lower dark respiration rates (R(d)), compared to the other treatments. It was found that the production of total phenolics, flavonoids and ascorbic acid are also higher under 270 kg K/ha compared to 180, 90 and 0 kg K/ha. Furthermore, from the present study, the invertase activity was also found to be higher in 270 kg K/ha treatment. The antioxidant enzyme activities (APX, CAT and SOD) were lower under high potassium fertilization (270 kg K/ha) and have a significant negative correlation with total phenolics and flavonoid production. From this study, it was observed that the up-regulation of leaf gas exchange and downregulation of APX, CAT and SOD activities under high supplementation of potassium fertilizer enhanced the carbohydrate content that simultaneously increased the production of L. pumila secondary metabolites, thus increasing the health promoting effects of this plant.