Ecological Risk Assessment

An ecological risk assessment is the process for evaluating how likely it is that the environment may be impacted as a result of exposure to one or more environmental stressors such as chemicals, land change, disease, invasive species and climate change.

Every day, people face questions about environmental concerns, many of them related to plants, animals, ecosystems as a whole, and how we interact with them. These questions may be about potential risks such as impacts on the aesthetic value of a place due to physical alterations, effects of pollution on endangered species, or the consequences of long-term release of contaminants to an ecosystem.  For example:

• How would the construction of a dam impact fish populations in nearby water bodies?
• Can the residential or agricultural application of an insecticide end up harming an endangered bird species?
• Do contaminants in the environment from an abandoned industrial or mining facility significantly reduce the use of the site and to nearby areas?
• What is the risk of introducing a non-native oyster to an estuary?
• How does fertilizer runoff reduce oxygen levels in water bodies such as bays?
• Are some plants or animals more likely to be susceptible to environmental stressors because of factors such as age, genetics, body size, or differences among species?

The use of risk assessment and management techniques in policy and regulatory decisions

Risk assessment and management approaches to environmental issues are increasingly being used at all levels of policy and regulation. The techniques have a wide range of application, including;

• the design of regulation, for instance in determining societally "acceptable" risk levels which may form the basis of environmental standards; Example
• providing a basis for site-specific decisions, for instance in land-use planning or siting of hazardous installations; Example
• prioritisation of environmental risks, for instance in the determination of which chemicals to regulate first; Example
• comparison of risks, for instance to enable comparisons to be made between the resources being allocated to the control of different types of risk, or to allow risk substitution decisions to be made. Example

The use of risk assessment and management techniques in industry
ERA has traditionally been a function of policy and regulatory agencies and most development has taken place in these fields. ERA is becoming more common in industry partly as a result of the use of ERA in regulation.
ERA is used in industry in the following;

• Compliance with legislation
• Product safety
• Financial planning
• Site-specific decision making
• Prioritisation and evaluation of risk reduction measures

Wastewater Treatment Management
Wastewater treatment is closely related to the standards and/or expectations set for the effluent quality. Wastewater treatment processes are designed to achieve improvements in the quality of the wastewater. We provide  various treatment processes to reduce:

Suspended solids (physical particles that can clog rivers or channels as they settle under gravity)

Biodegradable organics
(e.g. BOD) which can serve as “food” for microorganisms in the receiving body. Microorganisms combine this matter with oxygen from the water to yield the energy they need to thrive and multiply; unfortunately, this oxygen is also needed by fish and other organisms in the river. Heavy organic pollution can lead to “dead zones” where no fish can be found; sudden releases of heavy organic loads can lead to dramatic “fishkills”.

Pathogenic bacteria and other disease causing organisms
These are most relevant where the receiving water is used for drinking, or where people would otherwise be in close contact with it; and

Nutrients, including nitrates and phosphates.
These nutrients can lead to high concentrations of unwanted algae, which can themselves become heavy loads of biodegradable organic load Treatment processes may also neutralize or removing industrial wastes and toxic chemicals. This type of treatment should ideally take place at the industrial plant itself, before discharge of their effluent in municipal sewers or water courses.

Widely used terminology refers to three levels of wastewater treatment: primary, secondary, and tertiary (or advanced).

Primary (mechanical) treatment is designed to remove gross, suspended and floating solids from raw sewage. It includes screening to trap solid objects and sedimentation by gravity to remove suspended solids. This level is sometimes referred to as “mechanical treatment”, although chemicals are often used to accelerate the sedimentation process. Primary treatment can reduce the BOD of the incoming wastewater by 20-30% and the total suspended solids by some 50-60%. Primary treatment is usually the first stage of wastewater treatment.

Secondary (biological) treatment removes the dissolved organic matter that escapes primary treatment. This is achieved by microbes consuming the organic matter as food, and converting it to carbon dioxide, water, and energy for their own growth and reproduction. The biological process is then followed by additional settling tanks (“secondary sedimentation") to remove more of the suspended solids. About 85% of the suspended solids and BOD can be removed by a well running plant with secondary treatment. Secondary treatment technologies include the basic activated sludge process, the variants of pond and constructed wetland systems, trickling filters and other forms of treatment which use biological activity to break down organic matter.

Tertiary treatment is simply additional treatment beyond secondary! Tertiary treatment can remove more than 99 percent of all the impurities from sewage, producing an effluent of almost drinking-water quality. The related technology can be very expensive, requiring a high level of technical know-how and well trained treatment plant operators, a steady energy supply, and chemicals and specific equipment which may not be readily available. An example of a typical tertiary treatment process is the modification of a conventional secondary treatment plant to remove additional phosphorus and nitrogen.

Disinfection, typically with chlorine, can be the final step before discharge of the effluent. However, some environmental authorities are concerned that chlorine residuals in the effluent can be a problem in their own right, and have moved away from this process. Disinfection is frequently built into treatment plant design, but not effectively practiced, because of the high cost of chlorine, or the reduced effectiveness of ultraviolet radiation where the water is not sufficiently clear or free of particles. 

Contact us today to see how we can help you with any Ecological Risk Assessment needs