Design and Develop a Cost-Effective Hydroponics Autodoser System

Ng, Yong Chuen (2025) Design and Develop a Cost-Effective Hydroponics Autodoser System. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Hydroponic systems offer sustainable benefits, but manual nutrient dosing methods pose challenges in ensuring optimal plant growth, particularly in large-scale operations. The development of a cost-effective, automated dosing system (autodoser) is essential for consistent nutrient management and, alongside safety research on hydroponically grown produce like lettuce, will help ensure food safety to reduce health issues related to excessive nitrate content. This project endeavors to design a functional yet cost-effective automated dosing system tailored for hydroponic cultivation. From the experiment, the autodoser has successfully grown the lettuce by ensuring the TDS value within the range of 501-700 ppm without human intervention for two weeks. Then, the purpose of this project is to assess the accuracy of the designed autodoser. It is found that the accuracy of the autodoser with the use of TDS sensor is high, with only 2.0% percentage error. The morphology of lettuce is studied using ANOVA to discover the difference in the mean mass of lettuce from Rack 1, 2 and 3 respectively. Ion chromatography is conducted to test the nitrate content of lettuces to assess their safe consumption. For Rack 1, the nitrate content of sample 1 and sample 2 are 5.16 (mg/kg) and 2.05 (mg/kg) respectively. For Rack 2, the nitrate content of sample 1 and sample 2 are 730.42 (mg/kg) and 724.26 (mg/kg) respectively. For Rack 3, the nitrate content of sample 1, 2, 3, 4, 5, and 6 are 445.53 (mg/kg), 24.71(mg/kg), 734.88 (mg/kg), 1513.23 (mg/kg), 2812.63 (mg/kg) and 219.33 (mg/kg) respectively. The nitrate content of sample 1 and sample 2 for outdoor hydroponics (extra) are 1791.72 (mg/kg) and 1221.69 (mg/kg). The nitrate content of sample 1 and sample 2 for outdoor hydroponics (extreme values) are 1266.44 (mg/kg) and 1937.49 (mg/kg). Therefore, the nitrate content of grown lettuces are within 3000-5000 (mg/kg) set by Commission Regulation (EU), which is safe for consumption. The relationship between TDS of the nutrient solution and the nitrate ion levels in lettuce through the proposed autodoser is studied. It is observed that the extreme low TDS values, which are 232 and 278 ppm, contributed to higher amount of nitrate content in lettuce, which are 1266.443 and 1937.493 respectively. By using linear regression, the relationship between TDS value and nitrate content of the lettuce is medium, 0.499. This means that while TDS is a factor in determining nitrate content, other variables are also playing significant roles like light intensity, pH values, temperature and humidity.