Low-cost composite autosampler for wastewater sampling

Wastewater monitoring is a proven method for detecting viruses, illicit drug consumption, pharmaceutical use/abuse, water pollution, and the occurrence of antimicrobial resistance genes. Analyzing sewage water for pathogens like the SARS-Cov-2 virus could enable early detection of infected areas or virus variants. We developed a low-cost (∼US$1000), open-source, composite automatic water sampler with operational flexibility and simple data logging. Sample quantity is measured and cut off appropriately by continuously weighing the incoming liquid. Our system is customizable in both its hardware and firmware (via options and code modification) which allows for the device to be tailored easily to each application. For example, the user can input sampling quantities from 10 g per sample every 1.5 min to a single 2900 g sample after up to a 16-day delay prior to sampling. The outer diameter and height of the sampler are less than 0.5 m to fit in human-entry openings. We present experimental data for sample sizes of 10 g and 100 g at suction heights between 0.65 and 4.75 m.