Browsing by Author "Kottehewa, D.J."

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    Analysis of Quality of Water in Sludge Drying Bed and Reusing Sludge Generated in Bandarapura Water Treatment Plant in Brick Manufacturing
    (Uva Wellassa University of Sri Lanka, 2020) Dissanayake, D.M.O.Y.; Kottehewa, D.J.
    The generation of large quantities of Aluminium rich sludge in the treatment process of Water Treatment Plants is an unavoidable problem all over the world. Aluminum sulphate and Aluminium chloride used as the coagulants in the water treatment process mainly cause for the sludge formation. Disposal of this Aluminium rich sludge in an economically and environmentally sustainable way is a major challenge faced by Water Treatment Plants. In Bandarapura Water Treatment Plant, after the dewatering process, dried sludge is being loaded on the ground beside the drying beds due to the lack of proper disposal facilities. This openly disposed of Aluminium rich sludge can cause hazardous effects to the environment as well as to the people. Hence, this urgently requires for a proper sludge disposal method to be in place and also for a feasible option for reusing the waste sludge. Studies have stated of reusing this waste sludge for brick manufacturing by combining with clay mixture after characterizing the sludge properties. Thus, the possibility of using sludge generated in Bandarapura Water Treatment Plants in Badulla in brick manufacturing was investigated in this study. Sludge percentages were increased from 0% to 20% with increments of 5%. Clay sludge mixing and brick preparation were done by hand pressing. Bricks were fired at two temperature batches as 850 and 1000 °C. Brick strength of 0.15 N mm-2 , water absorption of 13.06%, and Shrinkage of 0.4 cm were monitored. The bricks used for construction purposes require minimum brick strength of 2.0 N mm-2 which is not achieved by the prepared brick in this study. Nevertheless, the prepared brick can be used as a substitute for Interlocks. Keywords: Water treatment plant, Aluminium rich - sludge, Sludge disposal, Reusing sludge, Brick Manufacturing
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    Applicability of Grumusol Soil to Remove Cadmium from Textile Wastewater through Adsorption
    (Uva Wellassa University of Sri Lanka, 2020) Uditha, K.H.B.; Kottehewa, D.J.
    Heavy metals are well-known environmental pollutants. Today, it has become a serious problem in most of the countries in the world including Sri Lanka. The industrial sector can be considered as the major source of heavy metal pollution and in Sri Lanka, the textile industry has received a significant place. The processes like dyeing and finishing in textile manufacturing result in adding heavy metals into its wastewater. This generated wastewater typically contains environmentally harmful heavy metals like Cadmium. Failing to remove them properly will lead to accumulating them in surface water bodies and ultimately causing severe problems for human and aquatic ecosystems. Different methods have been tested for their suitability in removing heavy metals from wastewater amongst adsorption that has received much attention. For a country like Sri Lanka however, investigation of an economical, inexpensive, and safe method with having higher removal efficiencies is an essential and timely matter. The grumusol soil which can be easily found in Jaffna and Mannar districts in Sri Lanka has shown some special characteristics of a good adsorbent. The high cation exchange capacity, high clay fraction, high organic matter content, swelling and shrinkage properties, and the 2:1 clay mineral type bear evidence that it is worth to investigate the adsorption ability of grumusol soil. The primary objective of this study was to investigate the applicability of grumusol soil in removing heavy metals from aqueous solutions. In this study, cadmium (2+ ) ion was used as the selected heavy metal and the textile wastewater was used to check the adsorption ability of grumusol soil to remove Cd2+. The equilibrium time and effect of pH were investigated using the batch method. The results indicated that grumusol soil can adsorb cadmium ions with higher efficiency. The reaction is pH-dependent and the adsorption capacity of the grumusol soil increases with the increment of pH from 2 to 7 and maximizes at pH 10. The highest removal efficiency of 97.66% was recorded at pH 10 during the optimum equilibrium time of 6 hours. Keywords: Grumusol soil, Heavy metal pollution, Cadmium, Adsorption, Textile wastewater
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    Applicability of Using Rice Husk for Fluoride Removal from Drinking Water in Anuradhapura, Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2020) Thurairatnam, L.; Kottehewa, D.J.
    Finding low cost, environmentally friendly adsorbents with having higher removal efficiencies are vital to improve the quality of drinking water in the regions where groundwater is contaminated with fluorides. In Sri Lanka, this problem is apparent and has been prevailing especially in the north-central province. Rice husk is claimed to have better fluoride removal when used as an adsorbent. As a country known for its paddy cultivation, the waste material of it, the rice husk would be cheaper if can be used as a filter material. Therefore, this study was sought at investigating the efficiency of rice husk as a filter material in removing fluoride from groundwater. For that, bio-waste rice husk was converted to activated carbon by thermal activation and through merely treating with H3PO4. Characterization of Rice Husk Activated Carbon (RHAC) was carried out using the following methods: Fourier Transform Infra-Red (FT-IR), physical properties such as moisture content, ash content, and bulk density were also determined. FT-IR analysis showed the presence of various functional groups such as C=O, C=C, –OH, and C-H on the surface of the adsorbent. Moisture content, ash content and bulk density were found to be 5.32 ± 0.06 %, 15.28± 0.22%, 535 ± 0.51 kg m-3 respectively. The effect of contact time and initial concentration were studied. Fluoride equilibrium time was found to be 120 minutes. Adsorption of Fluoride fits the Langmuir isotherm. Fluoride adsorption experiments were performed on the laboratory-scale column. The parameters obtained from the laboratory scale column were used to build the packed bed column using a scaleup approach.10.0 g of RHAC has the capacity of attaining 83% of fluoride removal for the initial concentration of 10 mg L-1 . Keywords: Rice husk activated carbon, Fluoride, Langmuir isotherm, Packed bed column
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    Designing a Wastewater Treatment Plant for the Wastewater Discharge from Seafood Market
    (Uva Wellassa University of Sri Lanka, 2020) Suthassna, S.; Kottehewa, D.J.; Udagedara, T.
    Seafood is the main interest in the coastal areas; hence seafood markets are centralized towards the city and highly crowded place. A seafood market includes many varieties of fishes, crabs, clams, prawns, lobsters, cuttlefish, etc. from saltwater as well as from freshwater. In general, wastewater generation from the seafood market is not given much attention and thus, lack of awareness about the problematic factors associated with that. The wastewater from this mainly contains blood, shells, fines, fish heads, offal products, and detergents used for cleaning and washing. In this study, the wastewater generated from the seafood market in Trincomalee was investigated. The wastewater characterization was done for 5 months. The results of the wastewater characterization showed that the average value of pH, Total Suspended Solids (TSS), Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD) were 7.62, 195.2 mg L-1 , 870.20 mg L-1 , and 88.20 mg L-1 , respectively which are exceeding the tolerance limit set by Central Environmental Authority of Sri Lanka. The oil and grease, nitrate, and phosphate are within the tolerance limit set by the Central Environmental Authority of Sri Lanka. The BOD: COD ratio was 0.1, which implies that the wastewater is less biodegradable, and biological treatment is not suitable in this case. The design of the wastewater treatment plant was proposed with chemical coagulation as a pre-treatment. Bar rack was placed as a preliminary treatment, then equalization tank was designed to control the flow variation, next the coagulation tank was followed by a clariflocculator. Finally, the design of the wetland with aerated Hyacinth system with recycle was proposed. Additionally, COD removal efficiency was checked with bio sorbents prepared using Water Hyacinth and Rice husk. Keywords: Sea food market wastewater, Wastewater characterization, Designing wastewater treatment plant
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    Investigating the Effectiveness of Mycofiltration in Treating Greywater Generated at Uva Wellassa University for Recycling Purposes
    (Uva Wellassa University of Sri Lanka, 2021) Kasilingam, S.; Kottehewa, D.J.
    Greywater is the waste-water from domestic activities. It is used water of kitchen, bathroom and laundry activities which represents least polluted contaminants as it consists of organic and inorganic contaminants, nitrogen and phosphorus derivatives, oil, food particles and fats. Mycofiltration is one of the bioremediation techniques in which fungus is used for treatment of greywater. Daily 720 000 L of greywater is generated at Uva Wellassa University (UWU). However, this wastewater is discharged into drainage without any proper treatment. This study was therefore taken to treat greywater generated at UWU using myco filters and to investigate their effectiveness for recycling purposes. Greywater samples were collected in sterilized plastic containers and initial physico- chemical parameters such as pH, BOD, COD, nitrogen, total suspended solids (TSS), alkalinity, turbidity, conductivity, total dissolved solids (TDS) and colour were analyzed using the standard methods. Mycofiltration was performed using two different fungi namely Aspergillus niger and Pleurotus ostreatus in two different permeated substrates namely rice and saw dust. Greywater samples was allowed to pass through four different types of myco filters. Physico-chemical parameters of filtered water were analyzed again. pH, BOD, COD, nitrogen, TSS, and alkalinity parameter values have been reduced from the initial value and turbidity, conductivity, TDS and colour parameter value have been increased from the initial value. Removal efficiency from Aspergillus niger for both permeated substrates rice and sawdust were 43.76% & 35.92%. Removal efficiency from Pleurotus ostreatus for both permeated substrates rice and sawdust was 34.52% & 26.80%. Therefore, Aspergillus niger in rice media was chosen as the effective fungi in reducing contaminants present in greywater. Furthermore, the quality of Aspergillus niger in rice media filtrated water sample was compared with the standard permissible level for outdoor gardening given by Central Environmental Authority standards. Major parameters of Aspergillus niger in rice media filtrated water were below the permissible level. Hence, it was concluded that the greywater filtered through Aspergillus niger in rice media can be reused for outdoor gardening. However, this removal efficiency could be further increased by the use of bio coagulants along with myco filters in future. Keywords: Greywater; Mycofiltration; Aspergillus niger; Pleurotus ostreatus; Reuse
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    Performance Evaluation of Electro-Coagulation Process Using Different Electrodes for Removing Hardness from Drinking Water
    (Uva Wellassa University of Sri Lanka, 2020) Santhusan, T.; Kottehewa, D.J.
    The presence of hardness in water is problematic when it comes to water treatment. Many different removal methods are in use for removing hardness from the water. However, each has its advantages and disadvantages. Amongst those, electrocoagulation has gained much attention as it outperforms other methods due to its simple and fast process. This study aims to investigate optimum pH and retention time to achieve maximum removal of hardness using the Electrocoagulation process using an aluminum anode and an iron cathode. The electrode area, the distance between two electrodes, and potential differences in the Electrocoagulation process were kept constant during all the experiments as in 30 cm2 , 5 mm, 20 V respectively. The concentration of hard water, 500 ppm was synthetically prepared to mimic the concentration of hardness in groundwater in the Jaffna peninsula. The prepared solution was filled into the container and the Electrocoagulation process was run with changing initial pH and retention time. At the end of the experiments, the hardness of the water samples was measured by using EDTA titrimetric method. Experimental results showed a maximum hardness removal efficiency of 84% at initial pH 8.5 during 60 minutes retention time. Keywords: Hardness, Electrocoagulation, Aluminum anode, Iron cathode, Jaffna Peninsula
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    Proposing an Economical and Effective Treatment Process for Reverse Osmosis Concentrate in Brackish Water Desalination Using Chlorella sp.
    (Uva Wellassa University of Sri Lanka, 2020) Kayathri, V.; Kottehewa, D.J.
    Currently, brackish water desalination is practiced through reverse osmosis technology as it utilizes lower energy for high and stable quality water products. Though it produces high-quality water, around 15-35% of raw water is discharged as a waste concentrate which is problematic in terms of environmental and economic aspects. This study is to propose a cost-effective as well as efficient method to treat Brackish Water Reverse Osmosis (BWRO) concentrate through exploiting Chlorella sp. Isolated Chlorella sp. was grown in photobioreactor where sunlight was used as a light source and concentrate was used as an inorganic carbon source. Chlorella sp. were inoculated at 15% (v: v) in 250 mL Erlenmeyer flasks and kept in rotation at 250 rpm without aeration. Algae were grown in three different concentrates separately in the batch model. The retention time of the batch model was 9 days in which on the last day maximal of 1.16 g L -1 of biomass was produced. Total dissolved solids, electrical conductivity, alkalinity, total hardness, nitrate, and phosphate were able to remove with efficiencies up to 63.07, 63.42, 80.39, 74.36, 88.28, and 88.79% respectively. 1 m3 of concentrate was effectively treated in a surface area of 0.12 m2 of the photobioreactor. Due to the lack of discharge standards for reverse osmosis concentrate, the treated water quality of concentrate was compared with its feed water to check whether discharging in to surface water bodies and recycling is possible. The comparison studies showed that concentrate with high salinity, hardness, and alkalinity approximately met its feed water quality after batch model treatment which is harmless on discharge. Keywords: Chlorella sp., Brackish water reverse osmosis concentrate, Inorganic ion removal, Nutrient removal
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    Removal and Recovery of Phosphate using Sorption from Wastewater: Effect of Process Parameters and Modeling
    (Uva Wellassa University of Sri Lanka, 2021) Fara, M.N.N.; Kottehewa, D.J.
    Wastewater contains P (Phosphorus) from human excreta, household detergents and some industrial and trade effluents in the form of orthophosphates, organic compounds and polyphosphates. Out of these, phosphate is the most available form of P. Thus, the need for the removal of excess phosphate is a necessity. Since P is a nutrient, release of wastewater containing excess P could lead to create problems of eutrophication. Apart from that, P is a finite resource, therefore, recovery of P from wastewater is also of interest. Sorption has been given importance in this regard mainly by using Activated Carbon (AC). However, use of kinetics and adsorption isotherm models to describe this P sorption process on to AC is limited in the literature. Therefore, this study is sought at describing adsorption kinetics and equilibrium adsorption isotherms of P on to AC and the desorption process to enhance the recovery of phosphate. Different reaction parameter impacts on the adsorption process were tested. Experiments were conducted with synthetic solutions having an initial P concentration of 25 ppm prepared by using KH2PO4. Results of the kinetic study done in triplicate showed that the phosphate removal reached its maximum value (38.37%) after four hours and thirty minutes. The Elovich model fit well with the kinetic study experimental data explaining that the rate of adsorption of P on to AC gets decreased exponentially as the amount of adsorbed P on to AC increases. Equilibrium isotherm study results suggested that this adsorption process could be well explained by the Langmuir model with the maximum adsorption capacity of -0.5488 mg g-1. The results also revealed that the pH of the solution significantly influences the adsorption process as P removal efficiency is considerably decreased from lower pH to higher pH. Desorption study w results showed that the phosphate adsorbed by AC could be successfully desorbed using 1 M NaOH solution up to 84.17% after 1.6 hrs. Keywords: Phosphorus; Adsorption; Elovich model; Langmuir model; Desorption
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    Removal of Phosphorous and Nitrogen from Wastewater of Uva Wellassa University by utilizing Bittern Solution
    (Uva Wellassa University of Sri Lanka, 2021) Kalansooriya, J.M.P.; Kottehewa, D.J.
    Fluidized bed reactors (FBRs) are one of the best methods used for phosphorous recovery as Struvite crystallization from municipal wastewater streams. This study aims to remove and recover of phosphorous (P) and nitrogen (N) from wastewater generated at Uva Wellassa University through struvite precipitation in air agitated fluidized bed reactor by utilizing bittern solution. Bittern solution is a by-product of salt manufacturing process used as a low-cost source for Mg source in this study. Operating conditions i.e., pH range, aeration rate, constant bittern solution inflow rate and hydraulic retention time (HRT) were tested for obtaining optimal conditions for both batch mode and continuous flow mode air agitated FBR setup. According to the batch mode experimental results, the maximum recovery efficiency of P (PO43--P) and N (NH4+-N) were achieved 98.29% and 19.82% respectively through 3.0 L/min aeration at 180 minute HRT. Considering the operational parameters of the batch mode air agitated FBR setup, aeration rate increment (from 1.0 L/min to 3.0 L/min) did not show any significant effect on P (PO43--P) removal efficiency. On the other hand, for continuous flow mode experiment, the P and N maximum removal efficiency were reached 80.62% and 5.19% respectively through 65.0 mL/min wastewater inflow rate at 60 minute HRT. While optimizing the HRT for continuous flow mode air agitated FBR setup, the HRT is proportional to the wastewater inflow rate. Hence, the optimal operational parameters of experiments were obtained as 9.0 - 9.5 pH range, 1:1 molar ratio of PO43-:Mg2+, 120 to 180 minute HRT and 1.0 to 3.0 L/min aeration for batch mode air agitated FBR setup. According to the experimental results batch mode is more suitable than continuous flow mode for removing P from municipal wastewater for achieving higher efficiency. Therefore, the findings of this research would be applicable in designing and operating pilot scale air agitated FBR for struvite crystallization from wastewater. Keywords: Air agitated Fluidized bed reactor; Phosporous removal; Struvite precipitation; Aeration; Hydraulic retention time; Batch mode