Water Hyacinth Research Articles

Bioethanol production from water hyacinth with isolated thermophilic microbial consortium from Kenya

Bioethanol production from water hyacinth with isolated thermophilic microbial consortium from Kenya

The Effect of Water Hyacinth (Eichhornia crassipes) Organic Fertilizer on The Vegetative Growth of Carrot (Daucus carota), Royal Chantenay Variety

This study conducted in Gasabo District, Nyacyonga marshland aimed to investigate the effect of water hyacinth (Eichhornia crassipes) organic fertilizer on the vegetative growth of the Royal Chantenay variety of carrot (Daucus carota). The experiment was conducted using a randomized complete block design (RCBD) with three replications. Four treatments were applied: T1 (control, no fertilizer), T2 (NPK 17-17-17), T3 (25% water hyacinth organic fertilizer + 75% NPK 17-17-17), and T4 (50% water hyacinth organic fertilizer + 50% NPK 17-17-17). The growth parameters assessed included plant height, leaf number, and root diameter. Results showed that the application of water hyacinth organic fertilizer significantly influenced the vegetative growth of Royal Chantenay carrot plants. T3 and T4 treatments enhanced plant height, leaf number, and root diameter compared to the control (T1) and NPK 17-17-17 (T2). The highest vegetative growth parameters were observed in T4, indicating that a higher concentration of water hyacinth organic fertilizer positively affected the growth of carrot plants. The findings suggest that water hyacinth organic fertilizer can be a viable alternative to chemical fertilizers in promoting the vegetative growth of Royal Chantenay carrot plants. The utilization of water hyacinth as an organic fertilizer can contribute to sustainable agricultural practices by reducing dependence on synthetic inputs.

Geotechnologies in the Assessment of Eutrophication in the Barra Bonita Reservoir, São Paulo, Brazil

Objective: The objective of this study was to identify locations with higher eutrophication and, consequently, susceptible to the emergence of macrophytes in the Barra Bonita reservoir, SP. Theoretical background: The presence of macrophytes, such as Eichhornia crassipes, is influenced by ecological succession driven by human activities like introducing exotic species and discharging untreated nutrients. Effective management, including buffer zones, is suggested to reduce eutrophication, though some studies question their effectiveness on a large scale. Method: The analysis of the Normalized Difference Vegetation Index (NDVI) was conducted using remote sensing images obtained from Landsat 8 and 9 satellites. As a criterion for data acquisition, corresponding data for the study region were obtained over a one-year temporal scale with a maximum cloud cover of 0%. Results and conclusion: Analyzing the images, it is observable that the month of June 2023 exhibited areas with a higher vegetation index and, consequently, eutrophication processes. This trend gradually decreased in the months of August, September, and November. Research implications: The analysis of satellite images revealed specific patterns of eutrophication, suggesting a direct correlation between the geographical distribution of nutrients and the potential proliferation of macrophytes. Additionally, comparative studies of nutrient concentrations in tributaries indicate that urban pollution, besides affecting local water quality, contributed to eutrophication in the Barra Bonita reservoir. Originality/value: Through the NDVI, the eutrophication possibility in Barra Bonita’s Reservoir was evidentiated.

Sustainable Development of ZnO Nanostructure Doping with Water Hyacinth-Derived Activated Carbon for Visible-Light Photocatalysis.

Water hyacinth (Wh) is an aquatic weed considered a nuisance in agricultural and fishing activities. Therefore, this study proposed repurposing this plant into activated carbon (AC). First, the ZnO-AC was precipitated and applied as a photocatalyst for degrading methylene blue. The preliminary photocatalytic test under UV irradiation identified the optimum ZnO-AC photocatalyst to degrade methylene blue (MB). The ZnO-AC photocatalyst recorded the highest degradation rate constant of 11.49 × 10-3 min-1, which was almost two-fold higher than that of ZnO (5.55 × 10-3 min-1). Furthermore, photocatalytic degradation of MB and carbaryl under sunlight irradiation by ZnO-AC demonstrated degradation rate constants of 74.46 × 10-3 min-1 and 8.43 × 10-3 min-1, respectively. To investigate the properties of ZnO-AC, several techniques were performed. ZnO-AC and ZnO exhibited similar results in morphology, crystalline structure, and Raman characteristics. However, ZnO-AC presented smaller pore diameters than those of ZnO, which enlarged pore surface area, and the presence of carbon-related groups implied the presence of AC on ZnO-AC surfaces. This can be attributed to the presence of AC on the ZnO surface, increasing the capture of surrounding toxic molecules and elevating the reaction density. This mechanism is attributed to promoting the degradation of toxic molecules. Therefore, using Wh as a carbon source for the transformation of AC can alternatively solve the problems of aquatic weed management and carbon storage strategies, and the application of AC in ZnO-AC photocatalysts can enhance photocatalysis.

Phytoremediation of Hexavalent Chromium Using Aquatic Plants in Nickel Mine Waste

The abundant wealth that Indonesia has is very profitable. Wealth is not only from natural resources, but wealth or biodiversity is also able to make Indonesia an independent country in managing its environment. One of the varieties that can be utilized is the existence of aquatic plants that can be used in the restoration of polluted environments. The ability of plants to recover from pollutants is called phytoremediation. Hexavalent chromium/ Cr(IV) is a hazardous waste originating from the washing of ore/open pit waste from rainwater washing. The quality standard allowed for Cr (IV), according to the Minister of Environment Regulation No. 9 of 2006, concerning the Quality Standard of Wastewater for Nickel Ore Mining Businesses and/or Activities is 0.1 mg/L. Besides being used to reduce pollutant loads, this aquatic plant can also provide aesthetic value because it has a very beautiful shape, type, color, and flowers. The purpose of this research is to find out which plants can be used to reduce hexavalent chromium levels. Variations of aquatic plants that can reduce levels of hexavalent chromium which are harmful to living things include water hyacinth/Eichornia crassipes; water hyacinth; Kayambang/ Salvinia Cucullata; Kiambang/ Apu Wood/ Pistia Stratiotes; Hydrilla verticillata; Water Bamboo/Equisetum hyemale; Water spinach / Ipomoea Aquatica; and Sagittaria lancifolia. This aquatic plant can reduce Cr (IV) up to 99.5%. The ability of these aquatic plants not only to reduce Cr (IV) but also to reduce TSS, BOD, and COD and to neutralize pH. The combination of several aquatic plants also provides a high effectiveness value.

Optimization of solvothermal liquefaction of water hyacinth over PTFE-acid mediated kaolin catalyst for enhanced biocrude production

The invasive nature of water hyacinth and the need for renewable energy sources have necessitated this research. Catalyst development through enhanced pore structure and process parameters optimization are requirements for effective mass transport during the biomass valorization and improved biocrude formation during solvothermal liquefaction process. In this present study, the effects of temperature (250–340 °C), residence time (10–20 min) and catalyst loading (10–13 wt%) on biocrude, biochar, gas yield, and biomass conversion were optimized using a Box-Behnken experimental design. The developed catalyst through the application of polytetrafluoroethylene (PTFE) for pore structure enhancement was characterized using SEM, BET and XRD techniques. The process optimization found maximum biocrude yield (32.0 wt%), minimum biochar yield (19.4 wt%) and maximum conversion efficiency (80.6%) at 340 °C, 20 min residence time, and 13 wt% catalyst loading. The GC-MS result of the biocrude produced at the optimum conditions (13 wt% catalyst loading) consists of ketones (32.2%), acids (22.3%) and had 65.2% carbon, 7.3% hydrogen, HHV of 29.4 MJ/kg and H/C ratio of 1.34 while an increment in catalyst loading of 20 wt% enhanced the overall biocrude properties with HHV of 35.50 MJ/kg. This result depicts the suitability of the PTFE modified acid treated kaolin for high quality biocrude production through valorization of water hyacinth into a candidate for renewable energy material.

Bioethanol Production from Water Hyacinth (Eichhornia crassipes) using Different Microbial Inoculants

Water Hyacinth (Eichhornia crassipes) is a weedy lignocellulosic material which represents the best substrate for the production of bioethanol in tropical countries due to its more availability and more biomass yield. For the fermentation and bioethanol production from water hyacinth, the different bacterial and fungal inoculants were used. Water hyacinth was obtained from ukkadam-valankulam lake, Coimbatore. These leaves were washed properly to remove soil and contaminants and dried for 3 hours at 120°C. It was grained into a fine powder and sieved using 1.5µm in diameter nylon sieve. The sieved material was cultured using different microbial culture such as Aspergillus oryzae, Aspergillus niger and Saccharomyces cerevisiae. After 21 days incubation, the culture was distilled using rotary vacuum evaporator and the produced bioethanol was analyzed by Fourier-transform infrared spectroscopy (FTIR) technique. The previous report showed, less yield only obtained using water hyacinth, potato peels, cassava peel and millet husks but this study produced highest yield using water hyacinth. This study indicated that water hyacinth is mostly available aquatic plant for the production of ethanol. The aim of current work is to understand the usage of water hyacinth as main substrate for bioethanol production using fungal inoculum. The microbial inoculants used for current study reported more potential for the production of bioethanol. This current work gives more economical value to water hyacinths and it can be cleared from all the waterways.

Dampak Adanya Pertumbuhan Eceng Gondok dalam Skala Besar Terhadap Ekosistem di Kawasan Danau Toba

Lake Toba, as one of Indonesia's natural wonders, is experiencing serious challenges related to environmental damage and water pollution caused by the large-scale growth of water hyacinth. The growth of water hyacinth is the result of irresponsible human activities, such as the disposal of domestic, industrial, agricultural and other waste that enriches nutrients in lakes. The aim of this research is to investigate the impact of large-scale water hyacinth growth in Lake Toba on the lake ecosystem. By using B.F.'s behavioral theory. Skinner as a framework, this research identifies human behaviors that contribute to water hyacinth growth and evaluates interventions that may be needed to address this problem. The research method used is library and literature study, with behavioral theory analysis to understand the relationship between stimulus and response in the context of water hyacinth growth. The research results show that human behavior, such as waste disposal and daily activities, plays an important role in the growth of water hyacinth in Lake Toba. The negative impacts of growing water hyacinth include decreasing water quality, increasing nutrient content, and disturbing animal life in the lake. By better understanding the factors that influence the growth of water hyacinth and its impacts, it is hoped that more effective interventions can be designed to maintain the sustainability of the Lake Toba ecosystem.

Sustainable Synthesis of Biopolymer Polyhydroxybutyrate (PHB) from Agro-residue by Brevibacterium casei with Emphasis on Degradation Analysis

The Polyhydroxybutyrate (PHB) polymer is a biodegradable microbial polyester that is intracellularly accruing due to the depletion of nitrogen and phosphorous resources and an increase in carbon supply. As part of this research investigation, Sudan Black B staining, fermentation, chloroform-sodium hypochlorite solvent-based extraction, and characterization of extracted PHB were used to isolate and identify organisms capable of producing PHB. Brevibacterium casei (OQ519751) was used to synthesize PHB biopolymer from agro-residues (orange peel, mangosteen peel, sugarcane bagasse, water hyacinth, and jackfruit peel). Using the Response Surface Methodology (RSM) and the Central Composite Design (CCD) has proven to be highly effective for optimizing PHB synthesis. The optimal conditions determined through RSM allowed Brevibacterium casei to produce significant amounts of PHB when compared to an unoptimized medium. The model demonstrated statistical significance, as indicated by the F-value of 19.96 with an associated p-value of <0.0001. Furthermore, with an optimized pH level of 7, temperature of 37°C, and yeast extract as the nitrogen source, the carbon source water hyacinth was found to synthesize an enhanced quantity of a PHB yield of 1.29 g/L from 2.2 g/L of dry biomass (58.63%). PHB characterization was done with the aid of FTIR (Fourier-transform infrared spectroscopy), XRD (X-ray diffraction), and TGA (Thermogravimetric analysis) analysis. The degradation study of PHB films was performed by soil burial method and morphological changes were scrutinized by SEM analysis. The results reveal that utilizing water hyacinth as a feedstock employs an enhanced production of PHB. This is the first report to synthesize maximum yield of PHB from Brevibacterium casei using water hyacinth as a substrate for production.

Efficacy of Water Hyacinth as Growing Media for Amaranthus in Open Water Culture, Hydroponics and Land Cultivation in Kuttanad Ecosystem

A field experiment was conducted in farmer’s field in north Kuttanad during the kharif season during June-July 2023 and repeated consecutively during August-September 2023 to evaluate the efficacy of open water culture with respect to yield and growth attributes of amaranthus cultivation against deep water culture hydroponics with and without water hyacinth as medium. The experiment was laid out in a Randomized Design (CRD), comprising six treatments with four replications. The treatments were T1: Open water culture without medium, T2: Open water culture with medium, T3: Hydroponics without medium, T4: Hydroponics with medium, T5: Land cultivation with a bed of water hyacinth alone as medium and T6: Control: soil culture-KAU-POP recommended dose of nutrients. The data revealed significant differences in plant height, number of leaves, leaf length and width, leaf area index, stem girth, root length and yield. Maximum plant height was recorded in T6 (Control- soil culture-Kerala Agricultural University (KAU) -POP recommended dose of nutrients) followed by T5 (Land cultivation with a bed of water hyacinth alone as medium). Highest leaf area index, stem girth and root length were in T6, but was on par with T5. The yield of the total harvest was significantly higher in T6, but was on par with T5, which proves the efficacy of water hyacinth as a growing medium for amaranthus cultivation. The lowest yield and growth attributes were recorded by T1 (Open water culture without medium) and T3 (Hydroponics without medium).

BIOCHAR AS A POTENTIAL SOIL CONDITIONER IN SALINE PRONE COASTAL AREA OF BANGLADESH

In the coastal areas of Bangladesh, salinity restricts normal crop production and increases with the desiccation of the soil. Recently, biochar has received great attention as a soil amendment to mitigate the detrimental effects of salinity stress. In this respect, a field experiment was conducted to examine the effects of biochars on soil properties and growth of okra (Abelmoschus esculentus L.) and to identify a suitable biochar amendment for salt-affected soils in coastal areas of Bangladesh. The experiment was conducted in a randomized complete block design (RCBD) with five replications. Three types of biochar (rice straw biochar, sawdust biochar and water hyacinth biochar) were applied @ 10 t ha-1 in a silt loam soil along with the control. Results showed that biochar application to the soil enhanced plant height, leaf number, leaf area, shoot fresh weight, shoot dry weight and yield of okra as well as improving the soil quality e.g. field capacity (FC), CEC, OC, total N, available P, S, K, and Ca. The application of water hyacinth biochar improved almost all of the growth and yield attributes of okra along with most of the soil properties than that of others. The results suggest that water hyacinth biochar might be recommended as a suitable soil amendment for better crop growth and soil quality. Moreover, water hyacinth biochar had significantly (P<0.001) higher surface area (205.40 m2g-1); consequently, higher capacity in salt and water adsorption which might prevent soil desiccation. Side by side, it significantly (P<0.001) increased the soil Ca content which might replace Na+ in the root rhizosphere minimizing the Na+ uptake by plants. Taken together, water hyacinth biochar could also be the best choice of organic amendments to reduce the suppressing effect of salinity stress in coastal areas of Bangladesh.

Adsorption of Phosphate by Two-Step Synthesis of Ceramsite from Electrolytic Manganese Residue/Dredged Sludge.

Carrying out research on the management of electrolytic manganese residue (EMR) is necessary to maintain the environment and human health. The dredged sludge (DS) and water hyacinth (WH) generated from dredging projects are potential environmental threats, and therefore suitable methods need to be found for their treatment. In this study, ceramsite was prepared by a two-step low-temperature firing method using DS and EMR as raw materials, WH as a pore-forming additive, and aluminate cement as a binder for the adsorption of phosphorus from wastewater. The optimal ratio and process parameters of the ceramsite were determined by mechanical and adsorption properties. The static adsorption experiments were conducted to study the effect of ceramsite dosage and solution pH on the removal of phosphorus. At the same time, dynamic adsorption experiments were designed to consider the influence of flow rate on its actual absorption effect, to explore the actual effect of ceramsite in wastewater treatment, and to derive a dynamic adsorption model that can provide technical support and theoretical guidance for environmental management.

Utility of metagenomics for bioremediation: a comprehensive review on bioremediation mechanisms and microbial dynamics of river ecosystem.

Global industrialization has contributed substantial amounts of chemical pollutants in rivers, resulting in an uninhabitable state and impacting different life forms. Moreover, water macrophytes, such as water hyacinths, are abundantly present in polluted rivers, significantly affecting the overall water biogeochemistry. Bioremediation involves utilizing microbial metabolic machinery and is one of the most viable approaches for removing toxic pollutants. Conventional techniques generate limited information on the indigenous microbial population and their xenobiotic metabolism, failing the bioremediation process. Metagenomics can overcome these limitations by providing in-depth details of microbial taxa and functionality-related information required for successful biostimulation and augmentation. An in-depth summary of the findings related to pollutant metabolizing genes and enzymes in rivers still needs to be collated. The present study details bioremediation genes and enzymes functionally mined from polluted river ecosystems worldwide using a metagenomic approach. Several studies reported a wide variety of pollutant-degrading enzymes involved in the metabolism of dyes, plastics, persistent organic pollutants, and aromatic hydrocarbons. Additionally, few studies also noted a shift in the microbiome of the rivers upon exposure to contaminants, crucially affecting the ecological determinant processes. Furthermore, minimal studies have focused on the role of water-hyacinth-associated microbes in the bioremediation potentials, suggesting the need for the bioprospecting of these lesser-studied microbes. Overall, our study summarizes the prospects and utilities of the metagenomic approach and proposes the need to employ it for efficient bioremediation.

Nutrient conditions influence allelopathic capabilities of Ludwigia adscendens and other tropical macrophytes against Microcystis aeruginosa

Abstract Macrophytes may release allelochemicals that suppress competing phytoplankton, although it is unclear how their effectiveness could be influenced by environmental nutrient conditions. To approach this, we conducted a series of bioassays against the bloom‐forming cyanobacterium Microcystis aeruginosa using extracts and exudates from potentially allelopathic macrophytes under varying nutrient conditions. We screened six different tropical macrophytes and identified antialgal effects in both extracts and exudates of Ludwigia adscendens, Persicaria barbata, Pontederia crassipes and Vallisneria spiralis. Growth assays indicated that extract inhibitory effectiveness decreased as nutrient concentration increased from 5% to 50% strength. Focusing on the potent antialgal extract of L. adscendens, we determined that its inhibitory effects were enhanced by specifically reducing the availability of either micronutrient or bicarbonate availability, indicating a role of these nutrients in protecting algal cells from allelochemicals. Bioactivity‐guided fractionation and ultra‐performance liquid chromatography – mass spectrometry analyses of L. adscendens extract indicated that ellagitannins were the major constituent of bioactive extract fractions, suggesting an antialgal mechanism common to other tannic compounds. Novel allelopathic alkaloids and terpenoid compounds also were described, although their mechanisms of action are unknown. Our findings provide evidence that the availability of carbon and micronutrients to cyanobacteria could influence the effects of macrophyte allelochemicals. This interaction between the nutrient environment and allelochemical sensitivity of cyanobacteria can be substantial, and studies or applications involving allelopathic interactions between macrophytes and phytoplankton should consider this.

Graphitic Carbon Nitride (g-C<sub>3</sub>N<sub>4</sub>) Microrods and Nanosheets Photocatalysts Immobilized on Water Hyacinth Cellulose Sponge for Photodegradation

In this research, the researchers successfully fabricated photocatalysts hybrid materials using g-C3N4 microrods and g-C3N4 nanosheets, which were coated on water hyacinth cellulose sponges. The optical properties of the photocatalysts hybrid materials, specifically the g-C3N4 microrods and g-C3N4 nanosheets, were analyzed using a UV-vis spectrometer. The morphology of the g-C3N4 microrods and g-C3N4 nanosheets photocatalysts was examined using different procedures, including FTIR (Fourier-transform infrared spectroscopy), XRD (X-ray diffraction), and TEM (transmission electron microscopy). The results obtained from the study indicate that g-C3N4 microrods exhibited a higher level of crystallinity or orderliness in terms of intramolecular orientation compared to g-C3N4 nanosheets. This suggests that the microrods possessed a more organized arrangement of atoms within the material structure. Furthermore, the energy bandgap values, as determined from the study, were found to be 2.25 eV for the microrods and 2.75 eV for the nanosheets. As part of this project, the photocatalysts, namely g-C3N4 microrods and g-C3N4 nanosheets, were utilized as coating materials for water hyacinth-synthesized cellulose sponges. This process led to the formation of hybrid materials known as g-C3N4 MCS (Microrods Cellulose Sponge) and g-C3N4 NCS (Nanosheets Cellulose Sponge). The efficiency and reaction rate of MB removal were then studied with various models such as First order reaction, Second order reaction, Pseudo first order reaction, Pseudo second order reaction and Elovich model. The results obtained from the research project indicated that the g-C3N4 NCS hybrid material exhibited a notably higher rate of organic degradation compared to the g-C3N4 MCS hybrid material. In conclusion, this research project successfully achieved the fabrication and characterization of a photocatalysts hybrid material using cellulose sponge from water hyacinth. The material demonstrated excellent performance as an absorbent and degradation agent for organic pollutants in water, highlighting its potential for practical applications in water treatment and environmental remediation.

Water Hyacinth (Eichhornia crassipes) As a Possible Alternative Energy Source: A Case Study for INSEE Cement Manufacturing Plant in Puttalam, Sri Lanka

Cement manufacturing is typically energy-intensive process and currently using alternative fuels partially or totally to replace fossil fuels to reduce the energy and environmental costs. Biomass is one of the main alternative fuel utilized by the cement industry with the potential to replace up to 20% of total energy demand. Water hyacinth (WH) is a problematic invasive alien species in aquatic ecosystems of all climatic zones in Sri Lanka. Because of it is non-edible, rapid growth, and freely available in larger quantities, WH has the potential to be used as biomass energy. Several countries have been studied for WH as feedstock for bioenergy production while physical and chemical composition of WH biomass has been tested by many researchers. However, biomass physiochemical properties may be varied by different place and conditions and there is no significant study for industrial application of WH biomass to burn in cement plant kiln as alternative energy source. Thus, this study aimed to elucidate the potential of WH biomass as an alternative energy source for the INSEE cement plant in Puttalam. The study was conducted in three selected reservoirs namely, Tabbowa reservoir (TR), Murukkuwatawana reservoir (MR), and Nawadankulama reservoir (NR) located in Puttalam district Northwestern province of Sri Lanka. The quantity of fresh and dry WH biomass was estimated with the WH covered area and fresh and dry weights of WH in unit area.WH covered area of in each reservoir during 2020 and 2021 was digitized directly in Google earth satellite images using Google Earth Pro software with help of visual interpretation techniques. WH biomass per unit area were measured by the subjective sampling method. WH samples from each reservoir were collected for analyzing biomass, and to determine the fuel characteristics such as net calorific value (NCV), Chlorine and Sulfur content, moisture, volatile matter, fixed carbon, and ash content. According to the results, the fresh WH biomass was recorded as 692.62, 389.85, 23.58 tons in 2020 and 3570.82, 584.53, 33.31 tons in 2021 in the TR, MR, and NR respectively, while the dry WH biomass was recorded as 41.65, 24.65, 1.31 tons in 2020 and 214.74, 36.96, 1.85 tons in 2021 in the TR, MR, and NR respectively. NCV of the WH composite sample was 12.02 MJ/kg. Moisture content, ash content, chlorine and sulfur content were recorded as 13.56%, 10.95%, 1.06%, and 0.14% respectively. Except for chlorine content, other parameters agreed with the acceptable limits for using WH as an alternative energy source for cement industry. To replace 1 ton of coal, 2.2 tons of dry WH were required from 35 tons of fresh WH biomass while to produce 1 ton of clinker, 0.32 tons of dry WH were required from 5.2 tons of fresh WH biomass. Since relatively large quantities are freely available and with high volatile content and calorific value, WH is suitable as an alternative energy source for cement industry. However, economic feasibility should be studied prior to the commercial application.
 Keywords: Alternative fuel, Biomass, Water hyacinth, Calorific value

Eichhornia crassipes Leaves as a Waste-derived Bio-Sorbent to Remove Organics and Nutrients from Rice Mill Wastewater

The increased rate of population growth resulted in the increased number of rice mill industries to fulfill the demand for rice. The rice mill wastewater contains a high load of organics and nutrients. Therefore, the direct discharge of wastewater into the environment may degrade the quality of the environment as well as causes adverse effects on human health. Among various methods to treat waste effluent, bio-sorption is a cheap and environmentally sound approach. Eichhornia crassipes is a noxious weed that spreads rapidly. Most of the tanks in Vavuniya are polluted by E. crassipes and it needs a sustainable solution. This study uses the leaves of E. crassipes to produce waste-derived bio-sorbent to treat rice mill wastewater. The wastewater was collected from one of the rice mills in the Vavuniya town area. The adsorption isotherm and adsorption kinetics experiments were conducted to find out the removal efficiencies of COD, nitrate, and phosphate from wastewater. The effect of the dosage of bio-sorbent (1-6 g/L) and the contact time (30-180 min) with the wastewater was studied to determine the optimum dosage and optimum contact time. The bio-sorbent showed maximum removal efficiencies of COD (54.5%), nitrates (58.1%), and phosphates (29.5%) at the optimum dosage of 4 g/L at 120 min. Based on the t-test, E. crassipes leaves significantly reduce COD, nitrate, and phosphate (p-value<0.05). However, COD and nitrate showed higher removal rates than phosphate. Further, long-term column studies should be conducted to apply the above technique in wastewater treatment plants in treating the rice mill wastewater in the real world. This study emphasizes that E. crassipes leaves have the potential to remove contaminants from wastewater as well as this would also help to minimize the spread of the weed to safeguard the environment. 
 Keywords: Eichhornia crassipes, Bio-sorption, Vavuniya tank, Water quality

Management of Free-floating Aquatic Weeds by Making Compost and Testing its Efficacy against Root-knot Nematode on Tomato

Aquatic weeds are one of the prime pollution causing agents in fresh water bodies of Sri Lanka. In Sri Lanka, free-floating aquatic weeds such as Salvinia molesta, Eichhornia crassipes, Azolla spp and Pistia stratiotes are proliferating quickly and invading rapidly to new water bodies where threatening biodiversity by impeding light penetration and altering BOD and COD of the waterbody. This research was aimed to manage the aquatic weeds by composting and testing its efficacy on root-knot nematodes. Aquatic weeds were collected, mixed with fresh cow dung in 1:1 ratio and allowed for decomposition for 21 days. The recommended dose of prepared different compost was applied to tomato along with garden compost as control. The experiment was conducted in Complete Randomized Design (CRD) with four replicates. The data on nutritional qualities of the compost, plant growth parameters, and gall index were recorded. The data were subjected to ANOVA using SAS 9.1 and Tukey's HSD multiple comparison test was used to determine the best treatment combination at P<0.05. Total Nitrogen (N) content of composts were ranging from 1.42% to 5.6%. The highest significant N value of 5.6% was recorded in the Azolla spp based compost whereas the lowest N value of 1.42% was recorded in control. The highest total Phosphorus (P) content of 3.47% was observed in P. stratiotes based plant sample, whereas the lowest P value of 1.32% was recorded in the E. crassipes based compost. The total Potassium (K) content of this plant sample ranging from 1.3% to 24.4%. The highest K value of 24.4% was recorded in P. stratiotes based compost. The lowest K content of 1.3% was observed in control. Significantly higher shoot height (37.57 cm, 36.53), root length (18.75 cm and 17.5 cm), lower gall index (3.5,1.0), lower goal length (1.5 mm and 1.2 mm) and lower goal diameter (0.95 mm and 0.8 mm) were recorded in the application of S. molesta and Azolla spp based compost, respectively (P<0.05). Considering superiority of N, P and K level, and nematode suppressing efficacy, S. molesta and Azolla spp. based composts are superior than other composts. Therefore, findings conclude that the compost made from aquatic weeds are good source of plant nutrition, and can be substitute to chemical nematicieds to manage the nematodes in organic agriculture. Extensive field studies are needed for recommendation 
 Keywords: Aquatic weeds, Azolla spp., Compost, Root-knot Nematode

Habitat Preference of Lesser Whistling Ducks (Dendrocygna javanica) in Selected Wetlands within Colombo Ramsar Wetland City

Lesser Whistling Ducks (LWD) (Dendrocygna javanica) mostly occur in flocks and inhabit lakes, ponds and marshes within freshwater wetlands. They feed mainly on plants taken from water (seed, shoots, tuber and leaves), vertebrates (fishes) and invertebrates (mollusks and worms). In this study, habitat preference of LWD in five selected wetlands in Colombo Ramsar Wetland City (CRWC); Beddagana Wetland Park (BWP), Diyasaru Park (DP), Heen Ela Marsh (HEM), Thalangama Marsh (TM) and Kimbulawala Wetland (KW) was studied from May 2021 to April 2022 as wetlands in urban areas act as the last resort for many resident and migratory bird species and play a major role in the assemblage and conservation of water birds. Habitats present in the selected wetlands were categorized as open water body, floating vegetation, trees, grassland, paddy field, shrubs, bare land. Percentage cover of each habitat type at each sampling site were estimated using quadrat method. LWD were surveyed using line transects of 100m in length, laid in each selected study site to cover representative habitats and observations were made up to 30m towards either side of each transect. Sampling was done in three time slots of the day, morning, mid-day and evening. Floating vegetation, open water body and grassland were the preferred habitat types of D. javanica in BWP, DP, HEM and TM. LWD were not recorded in KW. Floating vegetation (54.97%) was the most preferred habitat by LWD in each study site followed by open water body (24.70%) and grassland (15.82%) habitat types. Eicchornia crassipes (Common water hyacinth) and Salvinia molesta (Giant salvinia) were their most preferred floating vegetation type. Higher abundance of LWD was recorded in TM (83.22%) followed by DP (9.17%), BWP (4.16%) and HEM (3.45%). TM which had higher abundance of LWD had higher floating vegetation coverage (28%) and was rich with E. crassipes and S. molesta. Present study revealed that, LWD mostly used E. crassipes and S. molesta as their main foraging and resting sites. Management of invasive alien species have been undertaken in Colombo wetlands and as E. crassipes and S. molesta are alien species they are currently being removed. Therefore, outright removal of E. crassipes and S. molesta may not be suitable and a monitored removal program that will conserve this habitat type should be implemented in order to conserve the habitats preferred by LWD in CRWC. 
 Keywords: Lesser whistling ducks, Wetlands, Habitat preference

Efficacy of Flavonoids from Selected Plants in Controlling Callosobruchus maculatus on Cowpea Seeds (Vigna unguiculata)

Phytochemicals act extensive active against stored pest have long been exciting alternative to synthetic pesticides besides, evidenced flavonoids that among the plant constitute a rich source of bio-active chemical which are much safe with eco-friendly that applicable to protect insects. The experiment especially aims to investigating influence of flavonoids from the selected plants leaves such as Moringa oleifera (moringa), Lantenna camera (nayunni), Justicia adhatoda (adhathodai), Pepper nigrum (pepper), Annona reticulate (annona), Eichhornia crassipes (water hayasinth), Eucalyptus globules (eucalyptus), Citrus aurantiifolia (lime), Azadiracta indica (neem), Achyranthes aspera (nayuruvi), Ocimum tenuiflorium (thulsi), Cymbopogan citratus (lemon grass). Capsicum annuum (chilli), piper longum (thipilli) and Vitex trifolia (nochchi), located in Eastern Regions of Sri Lanka against cowpea weevil, Callasobruchus maculatus on stored cowpea seeds (V. unguiculata) during storage. 10 g of each leaf dry powder separately extracted with 100 mL of 80% aqueous methanol at room temperature and filtrates were transferred in to 100 mL conical flask and evaporated into dryness to over a water bath and used standard scientific method to obtained flavonoids. 200 cowpea seeds thoroughly mixed with 2 mg flavonoids and replicated thrice for one treatment. As similar manner other treatments and untreated control were designed and introduce with 5 pairs of newly emerged cowpea weevil, C. maculatus in 100 mL capacity plastic bottle with arranged in Complete Randomized Design (CRD) and started to monitor from 1st day after treatment (DAT). Adult mortality and number of eggs laid on seeds of each treatment were recorded daily until 6th DAT and retained for further 30 days to assess new progeny production of the weevil
 
 C. Flavonoids from J. adhatoda and P. nigrum shown excellent constituent to kill all the adult C. maculatus within 6 days followed by O. tenuiflorium (80%) and it was significantly (p≤0.05) as par with E. globules (72.6%) and A. indica (74%). Similarly, the flavonoids from these above mentioned leaves dry powders except P.nigrum significantly active against fecundity of an adult which shown J. adhatoda (6.3 egg/female), C .aurantiifolia (7 eggs/female) and O. tenuiflorium (7 eggs/female), however J. adhatoda totally affect the development of F1 new progeny production. According to the observations the differences were not statistically significant about the fecundity between the flavonoids from P. nigraum, A.indica and C.annuum. L.camera, E. crassipes and C. citratus did not show any significant effect on adult mortality, fecundity, new progenies as well as obtained much damage seeds next to control and obtained unsatisfactory results as untreated control while, M. oleifera, A. reticulate, V. trifolia and C. annuum obtained moderately against adulticidal activities of C. maculatus on cowpea seeds during the storage until 30 days. However, J. adhatoda proven its efficacy on cowpea seeds to control C. maculatus by highly effective to suppressing new progeny production and led without any damage in the seeds during the storage.
 
 
 Keywords: Flavonoid, Adult, Mortality, Callosobruchus maculatus, Justicia adhatoda