Virus movement in soil columns flooded with secondary sewage effluent

Abstract

Secondary sewage effluent containing about 3 x 104 plaque-forming units of polio virus type 1 (LSc) per ml was passed through columns 250 cm in length packed with calcareous sand from an area in the Salt River bed used for groundwater recharge of secondary sewage effluent. Viruses were not detected in 1-ml samples extracted from the columns below the 160-cm level. However, viruses were detected in 5 of 43 100-ml samples of the column drainage water. Most of the viruses were adsorbed in the top 5 cm of soil. Virus removal was not affected by the infiltration rate, which varied between 15 and 55 cm/day. Flooding a column continuously for 27 days with the sewage water virus mixture did not saturate the top few centimeters of soil with viruses and did not seem to affect virus movement. Flooding with deionized water caused virus desorption from the soil and increased their movement through the columns. Adding CaCl2 to the deionized water prevented most of the virus desorption. Adding a pulse of deionized water followed by sewage water started a virus front moving through the columns, but the viruses were readsorbed and none was detected in outflow samples. Drying the soil for 1 day between applying the virus and flooding with deionized water greatly reduced desorption, and drying for 5 days prevented desorption. Large reductions (99.99% or more) of virus would be expected after passage of secondary sewage effluent through 250 cm of the calcareous sand similar to that used in our laboratory columns unless heavy rains fell within 1 day after the application of sewage stopped. Such virus movement could be minimized by the proper management of flooding and drying cycles.

Transport and Retention of Manure‐Borne Coliforms in Soil

“…Dazzo et al (1973) found that only 10% of the fecal coliforms present in fresh dairy manure percolated below 13‐cm depth in soil; no coliforms were detected below a depth of 48 cm. Lance et al (1976) found that filtration through 250‐cm long columns filled with loamy sand reduced fecal coliform concentrations by about 3 logs during a 9‐d flooding period. Reneau et al (1975) concluded that soil layers restricted coliform bacteria movement to the groundwater system, and that the groundwater quality from the watershed would improve with distance from the pollution source as a result of dilution, sedimentation, and bacteria die‐off.…”

Pathogen Removal from Wastewater during Groundwater Recharge

“…Rainwater, being of lower conductivity than sewage effluents, may thus lead to reduced viral and bacterial adsorption or to desorption with the subse quent redistribution of these organisms within the soil profile. This phenom enon was well demonstrated via soil core studies under controlled laboratory conditions [8,34,40,41]. Landry et al [43] showed that virus penetration was more extensive in rainwater-rinsed cores than in wastewater-rinsed cores.…”

“…At the lower infiltration rates, the surface mat of sewage solids that formed on the soil surface may have contributed to the greater virus removals observed. Lance et al [8] found that poliovirus type 1 removal was not affected by infiltration rates in the range of 15 to 55 cm per day. More recently Lance and Gerba [52] found that increasing flow rates from 0.6 to 1.2 m per day resulted in increased movement of viruses down the column.…”

“…Viruses, on the other hand, are thought to be removed by the process of adsorption only [7]. Unfortunately, however, viruses cannot be considered as permanently immobilized because they have been shown to elute and migrate further in soil following rainfall events [8][9][10].…”

Monitoramento sanitário de um sistema integrado de tratamento de águas residuárias da suinocultura

“…A filtração e a ação biológica de microrganismos, habitualmente presentes nos solos não estéreis, são os principais fatores de remoção microbiológica. A ação biológica é particularmente efetiva nas camadas superficiais do solo, onde a presença do ar facilita os processos aeróbios, mais intensivos do que os anaeróbios, e onde a disponibilidade maior de alimentos possibilita a existência de maior população de microrganismos (3,4). O outro fator determinante para uma eficaz ação biológica é o tempo.…”