Odours from sewage treatment plants and how to treat them

OdourPro on 10 October 2018

Sewage treatment plants are vulnerable to odour complaints due to the nature of their operation and the contents of the wastewater they process. Their high visibility in the community make them very noticeable, making sewage odour control an important part of their neighbourly relations.

In addition, regulatory bodies are quick to investigate odours from sewage treatment plants due to their close proximity to residential communities and their high profile. The EPA in Australia enforces the Protection of the Environment Operations Act, which sets out severe penalties for noncompliance. Tier 1 offences can attract penalties of up to $5 million and seven years jail.

It is very important to understand sewage treatment plant odour control. We can help you understand your options and ensure compliance.

Sewage treatment plant odour problems

Sewage treatment plants have odour problems because they process septic waste from municipal wastewater systems. All through the wastewater network, bacteria feed on the organic waste in the system producing hydrogen sulphide gas. This gas is known for its powerful rotten egg odour.

There are normally three stages to sewage treatment although some stages can be combined. The first is the removal of solids through settling. This stage has the potential to release odours from septic wastewater before any treatment has been done.

The second stage is the main treatment phase. Oxidation and micronutrients are used to break down organic matter in the wastewater. While this process occurs, odours may be generated.

The final stage is removal of phosphates and nitrates. By this stage the wastewater has been treated sufficiently to reduce the risk of odour complaints.

Sewage odour control solutions

While it is impossible to control sewage plant odours without using technology, there are some practical steps that help to minimise the problem. The design phase of a new sewage plant should take into account prevailing wind directions and proximity to the community. The layout of a new plant should be optimised in terms of reducing odour impacts. Agitation of wastewater releases odours. The types of pumps used, flow rates and management of ponds should all be done in such a way as to reduce agitation.

Chemical dosing of upstream wastewater

sewage odour control

Chemical dosing unit

A major influence over the odour problems of a sewage treatment plant is the degree of septicity of the arriving wastewater. Chemical dosing systems in the municipal wastewater network reduce the formation of hydrogen sulphide and therefore reduce the odours. The reduction in H2S has the added benefit of reducing corrosion in the wastewater piping and equipment.

Extraction and filtration

Enclosing the inlet works and extracting the vapours for treatment is a common method of odour control for sewage treatment plants. This prevents odours from reaching the atmosphere and drifting across to residential or commercial neighbours. Both active carbon filtersbiofilters or a combination of the two can be used to treat the extracted vapours.

Micronutrient dosing

micro nutrient

Micronutrient additives

Choosing the right micronutrient additives for biological breakdown of organic waste can make a big difference to the severity of odours. OdourPro micronutrient additives cultivate the growth of facultative bacteria, which do not produce H2S during organic waste decomposition and therefore limit the odours from sewage treatment ponds.

Misting or vapour systems

The last line of defence for sewage odour control is to treat the air at the boundary of the sewage treatment plant. Misting systems spray an airborne odour treatment into the air, which neutralises odours in the vapour phase. Vapour systems have a different mechanism of operation and do not require water to create a mist. The odour treatment compound has excellent air suspension properties allowing it to drift in the air for long distances treating odours through contact.

Case studies

The Boulder Bay Wastewater Treatment Plant north of Newcastle was experiencing odour problems at the inlet to the plant. OdourPro implemented a number of ferrous chloride chemical dosing units in the upstream municipal wastewater system to reduce odours at the source. Hydrogen sulphide levels were significantly reduced along with the associated odours. Corrosion issues on the inlet piping were also improved by the ferrous chloride dosing.

Carbon filters were installed at a Clarence Valley caravan park. The small self-contained sewage plant on site was affecting the comfort of campers. Carbon filters reduce odours by up to 99.5 per cent.

Contact OdourPro for more information about sewage treatment plant odour control

OdourPro has the experience and technical knowledge to help you solve any sewage plant odour problem. Whether the solution lies in upstream chemical dosing, extraction and filtration, micronutrient dosing, or misting systems, OdourPro has the expertise to design and implement the system you need.

We provide both products and services for sewage treatment plant odour control. Odour control systems need to perform as per design continuously in order to prevent complaints. OdourPro also provides maintenance services to perform regular inspections and routine maintenance tasks so that you have peace of mind that your system is in peak condition.

Find out more about our sewage odour control solutions or call our expert team on 1800 510 704 to arrange a consultation.