Environmental Impacts of Using Municipal Biosolids on Soil, Plant and Groundwater Qualities

This study was conducted to evaluate the effect of three different rates of municipal biosolids produced in Qatar on plant characteristics and soil texture and its potential impacts on groundwater. Petunia atkinsiana, was used in this study. The experiment took place in a greenhouse in pots with soil mixed with 0, 3, 5, and 7 kg/m2 biosolids. Pelletized class A biosolids from the Doha North Sewage Treatment Plant were used. Results revealed significant differences in all measured parameters, which were affected by biosolid treatments compared to the control treatment. Electrical conductivity, pH, macro and micronutrients and heavy metals were significantly affected by biosolid treatments. The comparison of the discovered levels against the international acceptable ceilings of pollutants indicated the advantages of utilizing class A biosolids, as they were well below the international acceptable levels and showed the best test rates, indicating that the product is a sustainable and efficient organic fertilizer for ornamental plants. Furthermore, the results highlight no potential significant impacts on groundwater due to trace presence of heavy metals, owing to the nature of deep groundwater in Qatar and the usage of modern irrigation devices that fulfil the exact needs of plants in a harsh climate and high evaporation rate.

Environmental Evaluation of Land-Applied Pulp Mill and Municipal Biosolids

In terms of disposal options, a form of waste that has received much attention in recent years is sludge, the by-product of wastewater treatment from both industrial and municipal sources. Negative issues associated with traditional sludge disposal practices (e.g. landfilling or incineration) have resulted in an increased interest to find disposal alternatives such as applying the sludge, or biosolids, to land as a soil amendment for purposes such as agriculture, horticulture, and silviculture. The objective of this study was to assess the environmental impact of pulp mill and municipal biosolids land-application using a suite of ecologically-relevant biota. Based on the results of this study, it can be concluded that the practice of pulp mill and municipal biosolids land-application may indeed be a viable and environmentally-sound alternative to other traditional disposal methods. This study did not detect any obvious impact on biota from pulp mill and municipal biosolids land-application and run-off into receiving-water when compared to reference bioassays.

Environmental Evaluation of Land-Applied Pulp Mill and Municipal Biosolids

In terms of disposal options, a form of waste that has received much attention in recent years is sludge, the by-product of wastewater treatment from both industrial and municipal sources. Negative issues associated with traditional sludge disposal practices (e.g. landfilling or incineration) have resulted in an increased interest to find disposal alternatives such as applying the sludge, or biosolids, to land as a soil amendment for purposes such as agriculture, horticulture, and silviculture. The objective of this study was to assess the environmental impact of pulp mill and municipal biosolids land-application using a suite of ecologically-relevant biota. Based on the results of this study, it can be concluded that the practice of pulp mill and municipal biosolids land-application may indeed be a viable and environmentally-sound alternative to other traditional disposal methods. This study did not detect any obvious impact on biota from pulp mill and municipal biosolids land-application and run-off into receiving-water when compared to reference bioassays.

The ecological effects of land-applying municipal biosolids on nitrogen-fixing bacteria

The effects of municipal biosolids on nitrogen-fixing bacteria were assessed in a three month soil incubation study. Treatments included reference agricultural soils, soil amended with municipal biosolids or manure, and biosolids without soil. Nitrogen-fixation rates in reference and manure-amended soil were similar, and lower than in biosolids treatments; respiration rates showed similar trends. At test termination there was no difference between soil treatments for nitrogen-fixation, but some enhanced respiration in the biosolids-amended soils. Community structure was assessed using Biolog EcoPlates™ and denaturing gradient gel electrphoresis with a nitrogen-fixing gene (nifH). EcoPlate™ carbon utilization patterns corresponded with activity measures, with no difference among soil treatments at test termination. Nitrogen-fixing gene patterns showed a potential shift in community structure of biosolids-amended soils three months post-amendment. In general, the effects on the activity and structure of nitrogen-fixing communities were largely temporary; however, this study evaluated a one-time biosolids application. The potential for cumulative effects requires further investigation.

The ecological effects of land-applying municipal biosolids on nitrogen-fixing bacteria

The effects of municipal biosolids on nitrogen-fixing bacteria were assessed in a three month soil incubation study. Treatments included reference agricultural soils, soil amended with municipal biosolids or manure, and biosolids without soil. Nitrogen-fixation rates in reference and manure-amended soil were similar, and lower than in biosolids treatments; respiration rates showed similar trends. At test termination there was no difference between soil treatments for nitrogen-fixation, but some enhanced respiration in the biosolids-amended soils. Community structure was assessed using Biolog EcoPlates™ and denaturing gradient gel electrphoresis with a nitrogen-fixing gene (nifH). EcoPlate™ carbon utilization patterns corresponded with activity measures, with no difference among soil treatments at test termination. Nitrogen-fixing gene patterns showed a potential shift in community structure of biosolids-amended soils three months post-amendment. In general, the effects on the activity and structure of nitrogen-fixing communities were largely temporary; however, this study evaluated a one-time biosolids application. The potential for cumulative effects requires further investigation.

Assessing Ecological Impacts Of Land-Applied Municipal Biosolids : Effects Of Run-Off And Tile Drainage On The Aquatic Organisms Daphnia Magna, Hyalella Azteca And Lemna Minor

The effect of municipal land applied biosolids run-off and tile drainage on aquatic organisms Daphnia magna, Hyalella azteca and Lemna minor was analyzed through a series of standardized eco-toxicological tests. Treatments included reference soil, reference soil amended with Guelph biosolids and reference soil amended with Kitchener biosolids. The assessment was done on biosolids elutriate collected after the simulated rainfall off the ramps on day 1 after the application of biosolids, and day 40 planted versus unplanted soil. Respiration rates, behavioural analysis and survivorship were tested on the two invertebrates, while 7-day Growth Inhibition test was performed on the plant. Although there were some significant differences between the reference soil and soil amended with biosolids elutriate, they were mostly on day 1 and in concentrations that are not likely to happen in nature. The plant Lemna minor showed eutrophication potential in elutriate from Day 1. The results are showing that although there are potential toxic constituents in the municipal biosolids that can adversely affect the aquatic life in the receiving waters, they largely very temporary and for the most part in concentrations that are environmentally irrelevant. To be able to understand the potential of using biosolids on agricultural fields in Ontario, more analytical and eco-toxicological studies should be performed that are relevant to Ontario's laws and topography.

Assessing Ecological Impacts Of Land-Applied Municipal Biosolids : Effects Of Run-Off And Tile Drainage On The Aquatic Organisms Daphnia Magna, Hyalella Azteca And Lemna Minor

The effect of municipal land applied biosolids run-off and tile drainage on aquatic organisms Daphnia magna, Hyalella azteca and Lemna minor was analyzed through a series of standardized eco-toxicological tests. Treatments included reference soil, reference soil amended with Guelph biosolids and reference soil amended with Kitchener biosolids. The assessment was done on biosolids elutriate collected after the simulated rainfall off the ramps on day 1 after the application of biosolids, and day 40 planted versus unplanted soil. Respiration rates, behavioural analysis and survivorship were tested on the two invertebrates, while 7-day Growth Inhibition test was performed on the plant. Although there were some significant differences between the reference soil and soil amended with biosolids elutriate, they were mostly on day 1 and in concentrations that are not likely to happen in nature. The plant Lemna minor showed eutrophication potential in elutriate from Day 1. The results are showing that although there are potential toxic constituents in the municipal biosolids that can adversely affect the aquatic life in the receiving waters, they largely very temporary and for the most part in concentrations that are environmentally irrelevant. To be able to understand the potential of using biosolids on agricultural fields in Ontario, more analytical and eco-toxicological studies should be performed that are relevant to Ontario's laws and topography.