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Publication Open Access Multifactorial Drivers of Chronic Kidney Disease of Unknown Etiology (CKDu): A Review of Cadmium Exposure, Ultraviolet B B Radiation, and the Potential Role of Vitamin D Toxicity(Faculty of Engineering, 2025-09-09) Ariyawansha, R.T.K.; Basnayake, B.F.A.; Dharmasena, D.A.N.; Siribaddana, S.There are many research studies conducted to determine the cause/origin of CKDu for preventing this increasingly occurring disease, particularly among poor farmers. The disease is known to be multifactorial with heat stress enduring period > 3 months, but there is difficulty in distinguishing between harsher environments than endemic locations. This study identified that the likely cause is UVB actuating Vitamin D Toxicity (VDT), thus affecting the kidneys. Hence, a focused literature review was undertaken to find the links between cadmium (Cd), calcium, fluoride, enzymes, inhibitions, and the like. Moreover, 2nd law of thermodynamics was applied to determine the entropy differences between cold and hot source. The mean values of climate models were obtained from one publication on radiative forcing (RF) in the tropopause of 1.28 Wm- 2 and climate feedback (CF) 0.25 Wm-2K-1. The energy of RF was used to determine entropy value 𝑆𝑅𝐹(𝑈𝑉𝐵)at 𝑇2 = 230𝐾 as mean atmospheric temperature and the maximum temperature, 𝑇1 at locations. It was then equated to the energy value of UVB, 𝑄𝐶𝐹(𝑈𝑉𝐵) to be found between 1/273 and 1/𝑇1. It was also validated using CF. The endemic location resulted 3.697 Wm-2 at 303K, and low RH compared to 3.239 Wm-2 at 311 K high RH. Although there is much comfort in endemic location, the chances of VDT or heat stress are higher more so with Cd inhibition of enzyme 7-dehydrocholesterol reductase (DHCR7), which is crucial for cholesterol synthesis. Instead, 7-dehydrocholesterol in excess switches more to form VDT, causing symptomatic hypercalcemia. Cadmium can disrupt vitamin D metabolism, contributing to osteomalacia and osteoporosis, actuating hypercalciuria, an indirect marker of low-level cadmium exposure. The kidneys, already compromised due to cadmium (Cd) accumulation and reabsorption during systemic distribution, ultimately eliminate Cd via the urine. Notably, no significant Cd accumulation is observed in end-stage renal tissues. Further basic research is required to elucidate the VDT in response to UVB exposure.Publication Open Access Evaluation of the Knowledge Base in Agriculture and Food to Reduce and Prevent Chronic Kidney Disease of Unknown Etiology (CKDu)(Faculty of Engineering, 2025-09-09) Ariyawansha, R.T.K.; Basnayake, B.F.A.; Dharmasena, D.A.N.; Gamage, AKidney disease is a growing global problem, more so in tropical regions. The cause of CKDu is multifactorial and influenced by heavy metal (HM) contamination, inhibiting essential enzymatic reactions. Fertilizers and water contamination are believed to cause the disease. This study aimed to review the existing knowledge base, focusing on a transitional approach to advanced technologies with the least HMs and to use justifiable scientific reasoning supported by published data, to used to demonstrate the movement of Cadmium (Cd) at both low and high concentrations from applied fertilizer through the soil to grain and rice. The quantity of fertilizer applied per ha with the given Cd levels was equated to Cd concentrations in the harvested grain and rice per ha, considering positive or negative contributions from the soil. Weekly consumption levels of rice at the threshold limits by an average Sri Lankan were determined for low and high Cd levels in rice using the tolerance limits of two international standards. It is best to characterize watersheds and determine the movement of nutrients and HM in ferruginous soils. Hinderance to phosphate immobility in these soils can be overcome by applying biochar biofertilizer with possible enrichment of biofilm biofertilizers to replace totally inorganic fertilizers contaminated with HMs. Cd levels of 836.25 and 393.75 of the two publications equate to the assumed harvest: lowest 21.22, average 385.13, and the highest 1246.10 mg Cd ha-1. Allowable standards indicate that the weekly limit of a Sri Lankan to consume rice is 300 g, containing a high concentration of 0.2618 mg Cd kg-1 and 1kg or 604 g, having 0.1339 mg Cd kg-1 for an average harvest of 4350 kg.ha-1. Water contains HM, particularly arsenic from fertilizer and pesticides. Recommended researching while implementing phytoremediation, mechanized farming, preventing UVB, Integrated Pest Management (IPM), and organic agriculture with supporting technologies of watershed resource management.Publication Open Access Isolati on of Cd Removal Bacteria from Beira Lake, Colombo, Sri Lanka and Evaluati on of their Capacity in Cadmium Removal(Faculty of Humanities and Sciences, SLIIT, 2024-12-04) Thilakarathne, T; Lankika, S.P. C.; Mirihana, S.Cadmium (Cd), a heavy metal, is reported to be exceeding its consumable levels in the environment due to several anthropogenic acti viti es. Cd contaminati on thus challenges the ecosystems and human health due to its persistence and toxicity. It is confi rmed that bioaccumulati on of Cd leads to cancers and osteoporosis. Hence, concerning their eco-friendliness and cost-eff ecti veness, urgent remediati on methods are needed for clearing the issue of Cd-contaminated water and soil. The present study deals with three Cd-resistant bacterial strains isolated from Beira Lake, Sri Lanka; and named as TTCB, TTGB, and TTPB. The isolated strains are found to have performed remarkably eff ecti vely with the Cd removal effi ciencies of 97.4%, 97.5%, and 97.5%, respecti vely, as determined by an atomic absorpti on spectrophotometric assay. Their highest eff ecti veness was found at temperatures ranging from 30°C to 40°C and in a pH range of 6 to 7. Moreover, the isolated strains indicated higher Minimal Inhibitory Concentrati ons (1200 – 2000 ppm), confi rming a strong tolerance to Cd. It is highlighted that the MIC levels of the isolated strains are remarkable in comparison with the model organisms as Bacillus cereus ATCC 10876 and Pseudomonas aeruginosa ATCC (300 – 700 ppm). The resulti ng potenti ality of the isolated strains has suggested a promising bioremediati on applicati on for Cd- contaminated environments, off ering a valuable soluti on to address this pressing environmental issue.Publication Open Access Column Study for Adsorption of Copper and Cadmium Using Activated Carbon Derived from Sewage Sludge(hindawi.com., 2022-03-22) Al-mahbashi, N; Kutty, S. R. M; Jagaba, A. H; Al-Nini, A; Ali, M; Saeed, A. A. H; Ghaleb, A. A. S; Rathnayake, Umong the water-polluting substances, heavy metals stand out due to their carcinogenic and toxic effects on the creatures and environment. This study aimed to scrutinize the effectiveness of sewage sludge-based activated carbon in the removal of copper and cadmium from aqueous solutions in column study. Detection of breakthrough curves and related parameters was conducted by varying bed depths (3, 6, and 9 cm). The solution with an initial metal concentration (IMC) of 100 ppm was pumped to the column at a flow rate of 2 mL/min. In the process of copper removal, the breakthrough points for depths 3 cm, 6 cm, and 9 cm were achieved at 10 min, 15 min, and 60 min, respectively, whereas breakthrough points of similar depths in cadmium removal process were achieved at 5 min, 10 min, and 30 min, respectively. Adsorption kinetics were analyzed using the Adams–Bohart, Yoon–Nelson, and Thomas kinetics models. The Adams–Bohart model described only the initial part of breakthrough curves. The Thomas model represented the adsorption process with coefficients of determination (R2) ranging between 0.90–0.95 for cadmium removal and 0.89–0.96 for copper removal, while the coefficients of determination of Yoon–Nelson ranged between 0.89–0.94 for cadmium and 0.95–0.97 for copper. Yoon–Nelson was fitted well with copper removal data, while removal of cadmium data was best described by the Thomas model. This study demonstrated that using sewage sludge-based activated carbon to remove heavy metals is an alternative, more cost-effective option to reach the objectives of sustainable development.Publication Embargo Phytoremediation of heavy metals by calcifying macro-algae (Nitella pseudoflabellata): implications of redox insensitive end products(Pergamon, 2013-08-01) Gomes, P. I. A; Asaeda, TTo evaluate the phytoremediation of heavy metals in water and understand the biochemistry of end products of calcifying macro algae (charophytes), an 84-wk laboratory experiment was conducted. Eighteen microcosms were maintained with and without plants. These were given different heavy metal treatments: no heavy metals, 0.2 mg L−1 Cr6+ and 0.01 mg L−1 Cd. Accumulation observed to be 0.06% Cr by dry weight and for Cd it was 0.02%. The bioconcentration factors were 3000 and 25 000 for Cr and Cd, respectively. Ratios of heavy metal accumulation in alkaline (i.e., calcified areas) to acidic areas of plants were 6 to 4 (for Cr) and 1 to 1 (for Cd). This elucidated an association between heavy metal accumulation and calcification. This was validated by sequential extraction of sediments. It was shown that in microcosms with plants, the heavy metals were mainly in redox insensitive and less bioavailable carbonate bound form (39–47%). This was followed by organic-bound form (23–34%). Carbonate bound end products will ensure long term storage of heavy metals and after plant senescence these will not re-enter the water column.