Mercury (Hg) pollution threatens ecosystems and human health. Wastewater treatment plants (WWTPs) play a key role in limiting Hg discharges from wastewaters to rivers and lakes, but large-scale studies to estimate Hg loads and discharge at national levels are scarce. We assessed the concentration, flux, speciation, and removal of Hg in 64 (pre-study) and 28 (main study) municipal WWTPs throughout Switzerland. We also investigated the behavior and pathways of Hg along the various treatment steps in a state-of-the-art WWTP. The resulting dataset, representative of industrialized countries, provides an overview of (i) current Hg concentration ranges, (ii) average per capita loads, and (iii) wastewater Hg inputs into surface waters. The results allowed estimation of a total Hg (THg) load in Swiss wastewater of 130 ± 30 kg THg/year (15.7 mg/capita/y), of which 96 ± 4% is retained in sewage sludge. About 4.7 ± 0.5 kg THg/year (0.57 mg/capita/y) is discharged with the treated wastewater into surface waters. This corresponds to only 1.5–3% of the THg load carried by the major Swiss rivers, indicating that >95% of riverine Hg originates from other sources. The monomethyl mercury content was <0.11–8.6 ng/g in sludge (av. 0.23% of THg), and fractions were constant along the different treatment steps.

汞污染威胁生态系统和人类健康。废水处理厂（WWTP）在限制废水中的汞排放到河流和湖泊中起着关键作用，但是在国家一级进行大规模估算汞负荷和排放的研究很少。我们评估了整个瑞士64个（研究前）和28个（主要研究）城市污水处理厂中汞的浓度，通量，形态和去除。我们还研究了最新的污水处理厂中汞在各种处理步骤中的行为和途径。得到的代表工业化国家的数据集概述了（i）当前的汞浓度范围，（ii）人均负载量和（iii）废水向地表水中的汞输入量。结果可以估算出瑞士废水中的总Hg（THg）负荷为130±30 kg THg /年（15.7 mg /人/年），其中96±4％保留在污水污泥中。与处理后的废水一起，约4.7±0.5 kg THg /年（0.57 mg /人/年）被排放到地表水中。这仅相当于瑞士主要河流承担的THg负荷的1.5–3％，这表明超过95％的河流汞来自其他来源。污泥中的单甲基汞含量<0.11-8.6 ng / g（THg的约0.23％），并且在不同的处理步骤中其分数是恒定的。