Risto Juvonen

Composting of forest industry wastewater sludges for agricultural use

Water Science and Technology, 1999

The feasibility of composting of pulp and paper industry sludges was studied. The aim was to stud... more The feasibility of composting of pulp and paper industry sludges was studied. The aim was to study the progress of the composting process and the toxicity and applicability of the sludges in agriculture. Five different sludges were used: two biosludges and three biosludge and primary sludge nuxtures. The sludges were composted in seven piles, two smaller of them founded with leachates collection systems. The piles were monitored throughout the composting period by physical measurements, chemical analyses and toxicity tests. Also the lignin concentrations were measured from the sludges and from the soil as well as the amount of mycelium. The results showed that all sludges were easily composted and they will be suitable for the use as soil improvement m agricultural plant production. Toxicity of the sludges decreased during compostmg and all the sludges were proved to be non-toxic at the end of the composting. Heavy metal concentrations were low in all sludges and leachates. The leachates were also non-toxic and the concentrahons of nutrients were low.

Download

A new flash assay for measuring the toxicity of solid and colored samples

New Microbiotests for Routine Toxicity Screening and Biomonitoring, 2000

A new flash method for measuring the toxicity of solid and colored samples

Chemosphere, 1999

A new approach for determining the toxicity of solid and highly coloured samples was developed. T... more A new approach for determining the toxicity of solid and highly coloured samples was developed. The measurement is based on the BioTox TM test utilising bioluminescent Vibriofischeri. The measurements were done with solid samples taken from an old industry area using a luminometer capable of monitoring light emission in a kinetic mode. In the method the signal from the sample is measured immediately after getting into contact with the sample and again after an incubation period of less than one minute, and therefore no correction factors are needed. The results are comparable to the results obtained with the standard Vibriofischeri toxicity test (correlation coefficient r = 0,836) with a slightly reduced sensitivity but with many new features including ultra fast performance.

Download

Composting and utilization of forest industry wastewater sludges

Water Science and Technology, 2000

Two different forest industry wastewater sludges were composted in piles. The piles were founded ... more Two different forest industry wastewater sludges were composted in piles. The piles were founded with leachate collection systems. The aim was to study the progress of the composting process, the amount and quality of leachates as well as the toxicity of the sludges and leachates. The sludges consisted of mixtures of primary and biosludge. The piles were monitored for eight months by physical measurements, chemical analyses and toxicity tests. The leachates were collected for six months. The lignin concentrations and the amount of mycelium were measured from the sludges and from the soil. Test plots and control plots were established to a field with different amounts of composted sludge in order to study the applicability of the sludges in agriculture. The results showed that both sludges were amenable to composting. The original sludges were toxic but the toxicity decreased during composting and all the sludges were proved to be non-toxic at the end of composting. The leachates wer...

Toxicity of Freshwater Sediments in the Vicinity of an Old Sawmill: Application of Three Bioassays

Archives of Environmental Contamination and Toxicology, 2001

Toxicity of contaminated sediments collected from an old sawmill area and the downstream river-la... more Toxicity of contaminated sediments collected from an old sawmill area and the downstream river-lake system was assessed with three different bioassays. Survival and growth were used as endpoints in subchronic (10-day) test with Chironomus riparius and growth and reproduction in long-term (28-day) test with Lumbriculus variegatus. A microbial bioluminescent direct contact assay, the Flash test, was also included in the test set to measure acute toxicity. In every bioassay, sediment from a pool of the sawmill was found to be toxic, and some adverse effects were found in other sediments as well. The bioassays were then compared to chemical analysis results, which showed the presence of several toxicants. These results could not, however, be directly connected to any individual toxicant, nor did they show any obvious trend downstream from the mill.

Download

Método de lumi nes cên cia bac te ria na para a detec ção de agen tes de lim pe za e desin fe tan tes

... O peque no estu do foi rea li za do em uma indús tria de ali men tos para mos trar a apli ca ... more

Comparison of the total mercury content in sediment samples with a mercury sensor bacteria test and Vibrio Fischeri toxicity test

Environmental Toxicology, 2000

Abstract The suitability of a luminescent bacterial sensor strain Escherichia coli MC1061 (pTOO11... more

Automated color correction method for Vibrio fischeri toxicity test. Comparison of standard and kinetic assays

Chemosphere, 2001

We demonstrate in this study that the toxicity of solid and highly colorful samples can be measur... more We demonstrate in this study that the toxicity of solid and highly colorful samples can be measured with kinetic bioassay using luminescent bacterium Vibrio ®scheri. The Flash assay, named after the test protocol, is performed with a tube luminometer. In this method, each sample acts as a reference for itself, and therefore, the color correction is possible with minimal hands-on-time. The bacteria are dispensed into the sample and the signal is recorded continuously. The maximum signal received after immediately dispensing is compared to the signal after an incubation period. With many chemicals, the toxic eects are obtained after a very short contact time. However, dierent chemicals have dierent modes of toxicity. Thus, kinetic data from sample analyses after 15 or 30 min for this bacterium gives an additional dimension for obtaining reliable results. The performance of the test was compared to the standardized photobacteria test protocol with reference chemicals. The repeatability of the test was excellent. The coecient of variation was normally below 1% with 10 replicates.

Download

A battery of toxicity tests as indicators of decontamination in composting oily waste

Ecotoxicology and …, 2000

Download

Comparison of the total mercury content in sediment samples with a mercury sensor bacteria test and Vibrio Fischeri toxicity test

Environmental Toxicology, 2000

Abstract The suitability of a luminescent bacterial sensor strain Escherichia coli MC1061 (pTOO11... more

A new flash method for measuring the toxicity of solid and colored samples

Chemosphere, 1999

A new approach for determining the toxicity of solid and highly coloured samples was developed. T... more A new approach for determining the toxicity of solid and highly coloured samples was developed. The measurement is based on the BioTox TM test utilising bioluminescent Vibriofischeri. The measurements were done with solid samples taken from an old industry area using a luminometer capable of monitoring light emission in a kinetic mode. In the method the signal from the sample is measured immediately after getting into contact with the sample and again after an incubation period of less than one minute, and therefore no correction factors are needed. The results are comparable to the results obtained with the standard Vibriofischeri toxicity test (correlation coefficient r = 0,836) with a slightly reduced sensitivity but with many new features including ultra fast performance.

Download

Automated color correction method for Vibrio fischeri toxicity test. Comparison of standard and kinetic assays

Chemosphere, 2001

We demonstrate in this study that the toxicity of solid and highly colorful samples can be measur... more We demonstrate in this study that the toxicity of solid and highly colorful samples can be measured with kinetic bioassay using luminescent bacterium Vibrio ®scheri. The Flash assay, named after the test protocol, is performed with a tube luminometer. In this method, each sample acts as a reference for itself, and therefore, the color correction is possible with minimal hands-on-time. The bacteria are dispensed into the sample and the signal is recorded continuously. The maximum signal received after immediately dispensing is compared to the signal after an incubation period. With many chemicals, the toxic eects are obtained after a very short contact time. However, dierent chemicals have dierent modes of toxicity. Thus, kinetic data from sample analyses after 15 or 30 min for this bacterium gives an additional dimension for obtaining reliable results. The performance of the test was compared to the standardized photobacteria test protocol with reference chemicals. The repeatability of the test was excellent. The coecient of variation was normally below 1% with 10 replicates. Ó

Download

Uploads

Papers by Risto Juvonen

Log In