Persistence of poliovirus 1 in soil and on vegetables grown in soil previously flooded with inoculated sewage sludge or effluent.

Land disposal of sewage sludge and effluent is becoming a common practice in the United States. The fertilizer content and humus value of such wastes are useful for agricultural purposes, and the recycling of sewage onto the land eliminates many of our stream pollution problems. The potential exists for crops grown in such irrigated soil to be contaminated by viruses that may be present in the sewage. Studies were initiated to determine viral persistence in soil and on crops grown under natural conditions in field plots that had been flooded to a depth of 1 inch (2.54 cm) with poliovirus 1-inoculated sewage wastes. Lettuce and radishes were planted in sludge- or effluent-flooded soil. In one study, the vegetables were planted 1 day before flooding, and in another they were planted 3 days after the plots were flooded. Survival of poliovirus 1 in soil irrigated with inoculated sewage sludge and effluent was determined during two summer growing seasons and one winter period. The longest period of survival was during the winter, when virus was detected after 96 days. During the summer, the longest survival period was 11 days. Poliovirus 1 was recovered from the mature vegetables 23 days after flooding of the plots had ceased. Lettuce and radishes are usually harvested 3 to 4 weeks after planting.     

Virus movement in soil columns flooded with secondary sewage effluent.

Secondary sewage effluent containing about 3 X 10(4) 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 ground-water 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 continuosly 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.     

Virus movement in soil columns flooded with secondary sewage effluent.

Secondary sewage effluent containing about 3 X 10(4) 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 ground-water 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 continuosly 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.     

Listeria monocytogenes contamination of crops grown on soil treated with sewage sludge cake

A l -G hazali , M.R. & A l -A zawi , S.K. 1990. Listeria monocytogenes contamination of crops grown on soil treated with sewage sludge cake. Journal of Applied Bacteriology 69 , 642–647.
Listeria monocytogenes was found in the sewage sludge cake which is commonly used as an agricultural fertilizer in Iraq. Soils treated with this material were contaminated with the organism. Pot and field experiment showed that crops grown on treated soil became contaminated with L. monocytogenes and when alfalfa plant was grown on farmland soil treated with sewage sludge cake, listerias were found on 10% of 50 plants sampled at harvest, but the organism was detected only in low numbers on these crops (≤ 5 cells/g). This could add to the risk to animals and man.     

Listeria monocytogenes contamination of crops grown on soil treated with sewage sludge cake

Listeria monocytogenes was found in the sewage sludge cake which is commonly used as an agricultural fertilizer in Iraq. Soils treated with this material were contaminated with the organism. Pot and field experiment showed that crops grown on treated soil became contaminated with L. monocytogenes and when alfalfa plant was grown on farmland soil treated with sewage sludge cake, listerias were found on 10% of 50 plants sampled at harvest, but the organism was detected only in low numbers on these crops (less than or equal to 5 cells/g). This could add to the risk to animals and man.     

Investigation of keratinolytic and non-keratinolytic fungi grown above or below a 1-cm sewage sludge blanket

This study investigated the incidence of keratinolytic and non-keratinolytic fungi grown above or below a 1-cm sewage sludge blanket. The hair baiting method was used. Incubation was carried out at 23 and 37  °C. The number of keratinolytic fungi occurrences below a sludge blanket (anoxic conditions) was almost two times smaller than the number of fungal occurrences above this blanket (oxic conditions). The anoxic conditions did not significantly affect the number of non-keratinolytic fungi. Qualitative differences were also observed. Trichophyton ajelloi with its teleomorph Arthroderma uncinatum and some other fungi were found to prefer oxic conditions. In the case of non-keratinolytic fungi, the most evident differences were observed at 37  °C. Aspergillus fumigatus prevailed above a sludge blanket, while Pseudallescheria boydii was the predominating species below this blanket. The incidence of keratinolytic fungi was dependent on sludge physico-chemical characteristics: mainly on sludge organic matter stabilization (total nitrogen and ammonium nitrogen contents, proteolytic activity and C:N ratio) and hygienization (total and fecal coliforms) factors.     

Nickel in soil and maize plants grown on an oxisol treated over a long time with sewage sludge

Abstract

The major limitation for the use of sewage sludge in agriculture is the risk of soil contamination with heavy metals, and their possible transference to man via the food chain. The objective of this study was to evaluate the content of nickel (Ni) in soil by the two methods of digestion (HNO₃ + H₂O₂ + HCl and HClO₄ + HF), and in different parts of maize plants grown on a tropical soil classified as Typic Eutrorthox, that had been treated with sewage sludge for nine consecutive years, and the effects on dry matter and grain production. The experiment was carried out under field conditions in Jaboticabal-SP, using a randomized block design with four treatments and five replicates. Treatments consisted of: 0.0 (control, mineral fertilization), 45.0, 90.0 and 127.5t ha^?1 sewage sludge (dry basis), accumulated during nine years. Sewage sludge was manually applied to the soil and incorporated at 0.1 m depth before sowing the maize. Soil Ni evaluated by Jackson’s method was 76.8% higher than evaluated by the United States Environmental Protection Agency method that digests the samples by heating with concentrated HNO³, H²O² and HCl. Sewage sludge rates did not affect Ni content in the soil. Ni was accumulated in leaf and stem but was not detected in grain. Sewage sludge and mineral fertilization applied to soil for a long time caused similar effects on dry matter and grain production.     

Heavy-metal accumulation in crops grown on sewage sludge amended with metal salts

Poplar (Populus euramericana Robusta), oats (Avena sativa L. Leander), maize (Zea mays L. Ona 36), English ryegrass (Lolium perenne L.), butter head lettuce (Lactuca sativa L. Reskia), spinach (Spinacia oleracea L. Subito) and French beans (Phaseolus vulgaris Prelude), were grown in pots with pure sewage sludge (pH 6.7), amended with Cd, Cr, Cu, Ni, Pb and Zn acetates, either added singly or in combination, to study metal effects on plant growth and metal uptake. Phytotoxic metal doses varied with metal and plant species, increasing in the order Cd<Ni<Cu<Zn<Cr and Pb. The threshold dose of toxic metals applied in combination was generally lower than that of metals given singly. Addition of Cd, Ni and Zn was clearly reflected in the respective plant concentrations. This was much less so for Cu, whereas Cr and Pb concentrations were not affected in most plant species. Critical plant (leaf) metal concentrations were lower for metals applied in combination than for single metals. Because of such phenomena the use of critical levels as a diagnostic tool for determining potential multiple metal toxicity is limited.     

Terrestrial Chironomidae on agricultural soil treated with sewage sludge

Adult Chironomidae were caught in emergence traps for three subsequent years (1988–1990) on agricultural soil. Larvae were extracted from soil samples taken since June 1989. The field was subdivided into 5 plots treated with different amounts of sewage sludge. On some plots the sludge was artificially enriched with heavy metalts. The phenology of Chrinonomidae in the three years and their distribution over the different plots are discussed. The results suggest that the abundance of Chironomidae is increased by sewage sludge and appears to be also increased by heavy metals.     

Investigation of Salmonella infection in goats fed corn silage grown on land fertilized with sewage sludge.

A total of 36 goats were fed for 17 months with corn silage grown on land fertilized with human sewage sludge. These animals were investigated for salmonella infections. Salmonellae were not detected in cultures of fecal or silage samples. No significant agglutination titers were detected in goat sera examined. Salmonella newport C2 was isolated from the sludge used as fertilizer on the cornfields. The public health aspects of the findings are discussed as they relate to the increasing use of sewage sludge for agricultural fertilizers, as well as to the resultant effects on human food and livestock feed.     

Poliovirus removal from primary and secondary sewage effluent by soil filtration.

Adsorption of poliovirus from primary sewage effluent was similar to that from secondary sewage effluent in both batch soil studies and experiments with soil columns 240 cm long. Virus desorption by distilled water was also similar in a soil column that had been flooded with either primary or secondary effluent seeded with virus. These results indicated that absorption of poliovirus from primary effluent and virus movement through the soil were not affected by the higher organic content of primary sewage effluent.     

Poliovirus removal from primary and secondary sewage effluent by soil filtration.

Adsorption of poliovirus from primary sewage effluent was similar to that from secondary sewage effluent in both batch soil studies and experiments with soil columns 240 cm long. Virus desorption by distilled water was also similar in a soil column that had been flooded with either primary or secondary effluent seeded with virus. These results indicated that absorption of poliovirus from primary effluent and virus movement through the soil were not affected by the higher organic content of primary sewage effluent.     

Functioning and toxicity of artificial soil mixtures with metal-bearing sewage sludge

Various artificial soil mixtures were prepared by mixing two different toxic metals containing sewage sludge from Ljubljana and Maribor wastewater treatment plants with natural mineral soil. The plots with mixtures were exposed to field environmental conditions for a period of 1 year, after which we assessed soil toxicity (germination test with Lactuca sativa), potential metal phyto-accessibility (diethylenetriamine pentaacetic acid – DTPA extraction test), soil functioning (by soil enzymes activity) and conducted a field growth test with Lollium perenne L. as a metal bio-indicator plant. The metal phyto-accessibility extraction test (DTPA) showed lower values than the metal accumulation test with L. perenne L., which also showed higher metal concentrations in roots compared to leaves. With the exception of the mixture containing 30% (w/w) of sludge from the Ljubljana wastewater treatment plant, all mixtures containing more than 20% of sludge negatively affected root elongation of L. sativa seeds, indicating an increase in artificial soils toxicity. Increasing the ratio of sludge from the Ljubljana plant increased dehydrogenase and decreased phosphomonoesterase, while the addition of sludge from the Maribor plant increased phosphomonoesterase activity. Overall, the effect of sludge addition on artificial soil properties, toxicity and functioning not only depended on dosage but was also sensitive to the source and pre-treatment of the sewage sludge.     

Effect of water deficit on microbial characteristics in soil amended with sewage sludge or inorganic fertilizer under laboratory conditions

The potential impact of different types of organic (sewage sludge) or inorganic (mineral fertilizer) amendments to a basic soil was investigated under dry conditions. A soil incubation experiment was carried out over 64 days; there were two fertility treatments: sewage sludge (SS) (140 t ha(-1)), mineral fertilizer (M) and an unamended control (C). Two levels of irrigation were imposed: (1) well-watered, kept at 60% of its water holding capacity, and (2) water-deficit at 6%. Available N-NO3-, N-NH4+ and P, and electrical conductivity (EC) increased in SS and M-treated soils. Under well-watered conditions activities of some enzymes (protease-BAA, phosphatase and beta-glucosidase), and microbiological properties (microbial biomass carbon, basal respiration and dehydrogenase activity) were stimulated in SS-treated soils. Under water-deficit conditions, protease-BAA, phosphatase and beta-glucosidase activities, and basal respiration were more reduced in SS than in C and M. Results showed that under severe dry conditions, soil microbial activity always remained higher in organic amended soils than when mineral fertilizer was added.     

Inactivation of poliovirus in digested sludge.

The effect of anaerobically digested sludge on poliovirus during incubation at temperatures between 28 and 4 C was studied. Although virus was fully recoverable from sludge, its infectivity decreased in proportion to the time and temperature of incubation. The rate ranged from greater than 1 log per day at 28 C to about 1 log every 5 days at 4 C. The mechanism of inactivation was studied at the lower temperature where the sedimentation coefficients of most inactivated particles were not detectably modified. The ribonucleic acid (RNA) of these particles appeared to have been nicked and had an average sedimentation value about 70% that of RNA from infectious virus. Since the specific infectivity of RNA from particles recovered from sludge was directly proportional to that of the particles from which it was extracted, loss of infectivity was probably due to inactivation of RNA. Some breakdown was also found in the two largest viral proteins of inactivated particles. Thus, the mechanism of inactivation may be cleavage of viral proteins followed by nicking of encapsulated RNA. Because no virucidal activity was found in raw sludge, this component of digested sludge appears to be a product of the digestion process.     

Inactivation of poliovirus in digested sludge.

The effect of anaerobically digested sludge on poliovirus during incubation at temperatures between 28 and 4 C was studied. Although virus was fully recoverable from sludge, its infectivity decreased in proportion to the time and temperature of incubation. The rate ranged from greater than 1 log per day at 28 C to about 1 log every 5 days at 4 C. The mechanism of inactivation was studied at the lower temperature where the sedimentation coefficients of most inactivated particles were not detectably modified. The ribonucleic acid (RNA) of these particles appeared to have been nicked and had an average sedimentation value about 70% that of RNA from infectious virus. Since the specific infectivity of RNA from particles recovered from sludge was directly proportional to that of the particles from which it was extracted, loss of infectivity was probably due to inactivation of RNA. Some breakdown was also found in the two largest viral proteins of inactivated particles. Thus, the mechanism of inactivation may be cleavage of viral proteins followed by nicking of encapsulated RNA. Because no virucidal activity was found in raw sludge, this component of digested sludge appears to be a product of the digestion process.     

Inactivation of poliovirus in wastewater sludge with radiation and thermoradiation.

Sludge is highly protective of poliovirus against both heat and ionizing radiation. This protection could be largely overcome when these two treatments were given simultaneously.     

Phytoextraction capacity of the Chenopodium album L. grown on soil amended with tannery sludge

The metal accumulation potential of Chenopodium album L. grown on various amendments of tannery sludge (TS) was studied after 60 days of sapling planted. The analysis of the results showed that the levels of pH, cation exchange capacity, organic carbon, organic matter and DTPA extractable metals (except Mn) of amendments increased by the addition of tannery sludge ratio. Shoot length of the plant increased by the addition of sludge, whereas, no marked change was observed in root length, fresh and dry weight of the plant. Accumulation of the metals in the plants was found in the order; Fe > Mn > Zn > Cr > Cu > Pb > Ni > Cd. Translocation of toxic metals (Cr, Pb, Cd) in different parts of the tested plant was found in the order; leaves > stems > roots. An increase in the photosynthetic pigments, carotenoid and leaf protein contents of the plants were found to increase with increase in sludge amendments. Correlation analysis between metal accumulation in the plants with DTPA extractable metals emphasized that Mn, Ni, Cr, Pb and Cd showed positive correlation (p < 0.05), whereas, Fe, Zn and Cu showed negative correlation. Transfer factor analysis emphasized that 10% TS amendments were suitable for phytoextraction of Cr. Overall analysis of the data exhibited that the plants may be used for phytoextraction of Cr from tannery waste contaminated soil as most of the metal was accumulated in harvestable part which is a matter of serious concern, whenever used for edible purposes.