School of Sustainable Engineering and the Built Environment (SSEBE) Arizona State University P.O. Box 873005, Tempe , Arizona 85287-3005 , United States.
School of Computer Information and Decision Systems Engineering (CIDSE) Arizona State University P.O. Box 878809, Tempe , Arizona 85287-8809 , United States.
Environ Sci Technol. 2019 Mar 19;53(6):3187-3197. doi: 10.1021/acs.est.8b06126. Epub 2019 Mar 6.
This research used a cyber-physical system (CPS) to monitor and control the extent of urea hydrolysis in nonwater urinals. Real-time pH and conductivity data were used to control urea hydrolysis inhibition under realistic restroom conditions with acetic acid addition. Variable urination frequencies and urination volumes were used to compare three conditions that affect the progression of urea hydrolysis. Mechanistic and conceptual models were created to evaluate the factors that influence the progression of urea hydrolysis in nonwater urinals. It was found that low urination volumes at low frequencies created ideal conditions for urea hydrolysis to progress. Alternatively, high urination volumes at high frequencies created pseudo-inhibitory conditions because it did not allow for sufficient reaction time or mixing with older urine in the urinal trap. The CPS was used to control urea hydrolysis inhibition by two logics: (1) reactively responding to a pH threshold and (2) predictively responding to past measurements using four lasso regression models. Results from the control logic experiments showed that acid was added once per hour under low use conditions and once in a 4 h experiment for high use conditions. The CPS allowed for full control of urine chemistry in the nonwater urinal, reducing the conditions (i.e., clogging and malodor) that have led to the removal of nonwater urinals in the United States.
本研究使用一个网络物理系统（CPS）来监测和控制无水小便器中尿素水解的程度。通过添加乙酸，利用实时 pH 值和电导率数据来控制现实卫生间条件下的尿素水解抑制。采用可变的排尿频率和排尿量来比较三种影响尿素水解进程的条件。建立了机理和概念模型来评估影响无水小便器中尿素水解进程的因素。结果发现，低频率下的小排尿量为尿素水解的进行创造了理想的条件。相反，高频率下的大排尿量会产生假性抑制条件，因为它没有足够的反应时间或与小便器中的旧尿液混合。该 CPS 采用两种逻辑来控制尿素水解抑制：（1）对 pH 值阈值做出反应；（2）使用四个套索回归模型对过去的测量值进行预测性响应。控制逻辑实验的结果表明，低使用条件下每小时加一次酸，高使用条件下每 4 小时加一次酸。CPS 允许对无水小便器中的尿液化学进行全面控制，减少了导致美国去除无水小便器的条件（即堵塞和恶臭）。
