Water quality assessment has undeniable value for humanity’s well-being. Despite that, most of the existing techniques struggle to measure the quality of running water due to costly infrastructure or large evaluation time. Recently, quality measurement has been demonstrated using spectrum analysis. However, these modern systems need complicated signal processing algorithms and high processor capabilities for decision making, have elaborate optical assemblies and sizable power requirement making them bulky and expensive to operate. Thus, a refined technique with simplified implementation, low cost, and reliable long-time operation is essential to address this challenge. We present, for the first time to our knowledge, a holistic approach towards a simple and rapid method for determination of water quality parameters in flowing water. This is based on the selection of characteristic wavelengths for the parameters considered and usage of narrowband LEDs as the inspection light source. Thereby incorporating the benefits of optical sensing such as electromagnetic immunity, selectivity, sensitivity, etc. The specific wavelengths of 560nm, 860nm, and 635nm have been demonstrated to have a dominant effect due to pH, turbidity, and total dissolved solids (TDS) respectively, from regression analysis. Using only these wavelengths, an evaluation system capable of determining the light absorption after passing through water has been designed and developed. The obtained optical responses are subsequently related to water parameters, specifically pH, TDS, and turbidity. Experiments were performed to evaluate samples and then validate this technique against standard instruments for both flowing and sampled water setups. It is shown from the measurement results that pH, turbidity, and TDS have linear regression coefficients of 0.9773, 0.9617, 0.8271 and 0.9691, 0.9729, 0.76 for flowing and sampled water arrangements, respectively.

中文翻译：

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基于波长比吸收的流动水质量测量简单技术的发展

水质评估对人类福祉具有不可否认的价值。尽管如此，由于基础设施成本高或评估时间长，大多数现有技术都难以测量自来水的质量。最近，已经使用频谱分析证明了质量测量。然而，这些现代系统需要复杂的信号处理算法和用于决策的高处理器能力，具有复杂的光学组件和相当大的功率要求，使得它们体积庞大且操作昂贵。因此，一种具有简化实施、低成本和可靠长期运行的精细技术对于解决这一挑战至关重要。据我们所知，我们首次提出了一种简单快速的方法来确定流动水中的水质参数的整体方法。这是基于为所考虑的参数选择特征波长以及使用窄带 LED 作为检查光源。从而结合了光学传感的优点，如电磁抗扰性、选择性、灵敏度等。 560nm、860nm 和 635nm 的特定波长已被证明分别由于 pH、浊度和总溶解固体 (TDS) 而具有主要影响，来自回归分析。仅使用这些波长，就设计和开发了一种能够确定通过水后的光吸收的评估系统。获得的光学响应随后与水参数相关，特别是 pH、TDS 和浊度。进行了实验以评估样品，然后针对流动水和采样水设置的标准仪器验证该技术。测量结果表明，pH、浊度和TDS的线性回归系数分别为0.9773、0.9617、0.8271和0.9691、0.9729、0.76。