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Environmental Assessment of Proposed Pollution Mitigation Measures
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9. Environmental Assessment of Proposed Pollution Mitigation Measures
In this section, the proposed mitigations are assessed from the perspective of their positive impact on the environment in general and the ecological health and biodiversity of the Dnieper River Basin in particular.
The goals of facility personnel do not always coincide with the goals of the Dnieper River Basin Strategic Action Plan. GVK’s goals, are to develop a sustainable system for the provision of services to the service population. Those services being the provision of potable water as required by the population and industry and the collection, treatment and disposal of wastewater and associated wastes in a manner that is safe for the population, including downstream communities and the environment. The sustainable element to this goal has many dimensions including a financial viable system that is affordable to the population, a self-maintaining system that can rehabilitate or replace aging infrastructure and effective management that is efficient and can respond to changes demanded by the service population and industries. The goal of the Dnieper River Basin Strategic Action Plan is to improve the water quality in the basin, encourage biodiversity and mitigate adverse impacts on transboundary water systems.
The assessment of environmental benefits of each of the mitigation measures described in this report is summarized on the table below.
Table 9.1 : Summary of Environmental Benefits of Mitigation Measures
|
No. |
Project Description |
Direct Benefit to Dnieper Basin |
Indirect Benefit to Dnieper Basin |
Benefit to General Environment |
|
1 |
Replacing screens |
|
■ |
■ |
|
2 |
Rehabilitation of aeration tanks and introduction of denitrification |
■ |
■ |
■ |
|
3 |
Replacement of sludge dewatering system* |
■ |
■ |
■ |
|
4 |
Construction of sand filters treatment of effluents after final clarifiers* |
■ |
■ |
■ |
|
5 |
Installation of UV light disinfection system |
■ |
■ |
■ |
|
6 |
Expansion of sludge drying ponds |
|
■ |
■ |
|
7 |
Construction of effluent diffusers in the rivers |
■ |
|
■ |
|
8 |
Replacement of air blowers for aeration system |
|
■ |
■ |
Note: (*): These two projects are interdependent and must be undertaken together.
Direct benefits to the Dnieper River Basin indicate that the project will result in a measurable decrease in pollution loadings to the Dnieper River and/or pollutant concentrations in the effluent. A project having indirect benefits to the Dnieper River Basin include improved treatment efficiencies which may or may not result in an overall reduction in pollution loadings and pollutant concentrations to the river. General environmental benefits include improved operations that may result in reduction of emissions to the atmosphere from the treatment process or a reduction in energy consumption and/or other consumables such as treatment chemicals (e.g. flocculants).
One of the issues that is difficult to assess is the risk of a major failure in the treatment process resulting in a release of untreated or partially treated effluents to the river, causing a major upset and damage to the environment. As equipment and structures become aged and worn, the chance of such a failure increases. The hard work and ingenuity of GVK staff can only limit the possibility of such an occurrence. Without funds for implementing rehabilitation programs, such an event becomes inevitable.
The assessment of environmental benefits of each of the mitigation measures described in detail in the following sections.
Because only the facilities of the MWTP were surveyed during the reconnaissance phase of the operation, comments will be restricted to the eight projects proposed for this facility.
Main Wastewater Treatment Plant: Replacement of Screens
Poor operational efficiencies of the screens have a negative impact on downstream processes from the perspective of downstream operation efficiencies, increase maintenance requirements and equipment wear. Their replacement, however, would only have indirect benefits to the environmental condition of the river basin. Specifically, those benefits would be as follows:
- better treatment rates of pollutants in downstream processes with the primary clarifiers, aerations tanks and sludge digesters all benefiting (all are adversely affected by accumulated trash by-passing the screens);
- decreased wear on equipment and facilities extending the life-expectancies and minimizing the need for replacement (grit chambers, primary clarifiers, aeration tanks, sludge dewater equipment);
- new facilities have decreased chance of failure or breakdown which can result in spills, upsets and releases to the environment.
An important benefit to workers is reduced exposure to pathogens due to the automated trash handling systems in the proposed screens.
Negative impacts to the environment for implementing this project would be limited to the impacts of construction.
Main Wastewater Treatment Plant: Aeration Tanks
The Aeration tanks are the most important element of the treatment processes at the plant. The removal and elimination of most of the contaminants that have a negative impact on the river basin take place at this stage of treatment. In particular, the aeration tanks in place now can only manage partial denitrification of wastewater. After this project is implemented, full denitrification will be realized with the additional benefit of increased phosphorus removal. Compounds of nitrogen and phosphorus in the river basin are the cause of eutrophication in reservoirs both upstream and downstream of Kyiv. Eutrophication has adverse effects on water quality (decreased ability of river to recover from pollution loadings through natural processes) and biodiversity (decreased oxygen kills aquatic organisms). The discharges from the facility are likely contributing to the eutrophication downstream in a significant but not decisive way.
Indirect benefits to the environmental condition of the river basin would also be realized as follows:
- decreased wear on equipment and facilities extending the life-expectancies and minimizing the need for replacement (sludge dewatering, secondary clarifiers);
- new facilities have decreased chance of failure or breakdown which can result in spills, upsets and releases to the environment.
Negative impacts to the environment for implementing this project would be limited to the impacts of construction.
Main Wastewater Treatment Plant: Sludge Dewatering
Implementing effective and efficient sludge dewatering system (for both primary sludge and surplus activated sludge) will have a direct benefit to the river basin by improving the quality of the filtrate from the dewatering process to the top of the wastewater treatment system. It will also have indirect benefits by reducing the load on the sludge lagoons. Additionally, new facilities have decreased chance of failure or breakdown which can result in spills, upsets and releases to the environment.
Negative impacts to the environment for implementing this project would be limited to the impacts of construction.
Main Wastewater Treatment Plant: After-purification of Wastewater with Filters
The facility is discharging effluents with higher BOD and suspended solids than is desirable. This is having a direct adverse effect on water quality in the river and likely having an adverse impact on aquatic species. Additional treatment through sand filters will likely decrease the quantity of BOD and suspended solids in the river thus having a direct positive effect on the environment.
Main Wastewater Treatment Plant: Ultraviolet Light Disinfection
Similar to the previous project, the installation of an ultraviolet light disinfection system (or similar method) will reduce the loadings of pathogens being discharged to the river. This would have a positive effect on water quality and elimination of potentially adverse effects on nearby aquatic species. Thus, implementation of this project would be a positive impact on the environment.
Main Wastewater Treatment Plant: Sludge Disposal
Implementing an effective sludge disposal program for the sludge will have no direct benefits to the river basin but will have indirect benefits as follows:
- reduced risk of catastrophic release from lagoons;
- new facilities have decreased chance of failure or breakdown which can result in spills, upsets and releases to the environment.
Negative impacts to the environment for implementing this project would include the following:
- impacts of construction/rehabilitation;
- transport of sludge;
- disposal of sludge (agricultural land or landfilling).
Main Wastewater Treatment Plant: Outfall Reconstruction
In river diffuser outfalls are generally preferred over at-bank, above surface discharges due to improved mixing zones and minimization of adverse environmental effects. In particular, at-bank, free-fall of effluents into the river can create foaming problems which are not aesthetically pleasing and often the cause for public complaints.
