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Image of a wastewater lagoon with sludge


Sinking in sludge: How to identify excessive sludge accumulation

Many wastewater lagoons eventually face a common challenge—excessive sludge accumulation. This buildup can significantly impact the treatment process, causing several operational issues such as odours and elevated levels of BOD, TSS, and ammonia in the effluent. Here are the most common signs of excessive sludge accumulation and a simple approach to maintain optimal system efficiency and effluent quality.

Visible signs and odour

In some cases, sludge is visually apparent, with sludge islands floating on the lagoon’s surface or mounds rising above the water level. This exposed sludge can release methane or hydrogen sulfide gas, resulting in foul odours and complaints from nearby residents. Observing such phenomena means sludge should be addressed promptly.

Turbidity and effluent quality

Monitoring the lagoon through regular influent and effluent sampling is crucial for detecting sludge-related problems. High turbidity, poor nutrient removal, and changes in colour often indicate sludge accumulation. Sludge particles may also contaminate the effluent, reducing its clarity and leading to abnormally high or non-compliant total suspended solids (TSS) measurements.

Storage capacity, nutrient removal, and algae blooms

As sludge accumulation increases, a lagoon’s storage capacity and retention time decreases. This can impede the lagoon’s ability to effectively remove nutrients, which can cause problems such as algae blooms or exceedances in regulated discharge limits.

Short-circuiting and washout

Excessive sludge accumulation can create channels within the lagoon, causing wastewater to bypass the intended treatment process. This flow short-circuiting results in reduced retention time and compromises treatment performance. If a lagoon also experiences high hydraulic loading, such as a storm event, the high flow and short retention time can cause washout of a significant portion of the microbial population. It can take days, weeks or longer for the biological process to recover, significantly impacting lagoon performance.

Benthal feedback in non-aerated lagoons

Non-aerated lagoons can experience a phenomenon known as benthal feedback, particularly during the spring season. As the water warms, turbulence stirs up the sludge blanket, releasing accumulated hydrogen sulfide and nutrients. In severe cases, the concentrations of certain wastewater constituents can become higher in the effluent than in the influent, indicating a significant sludge-related issue.

Operator access and maintenance challenges

Excessive sludge can hinder operator access to critical components that require regular maintenance. Aeration systems, inlet structures, force mains, and other essential equipment may become blocked or inaccessible due to sludge accumulation. This obstruction can compromise routine maintenance and hinder the efficient operation of the lagoon.

Fast, affordable remediation options

Regular maintenance, including timely sludge removal, is key to ensuring the long-term effectiveness of lagoon systems. Bishop Water provides comprehensive services to remove and dewater sludge from wastewater treatment lagoons of all sizes.

Geotube containers collecting and dewatering sludge from wastewater lagoons.

Depending on the situation, urgency and budget availability, a total cleanout might be the right approach, or a partial cleanout to remove sludge only from areas of concern and defer the full cost to a future fiscal year.

Once a plan is ready, our team can begin mobilizing sludge removal equipment and the Bishop Solids Management Solution. This process provides a simple and cost-effective way to collect, dewater and contain sludge and achieves a high level of dry solids using only polymer conditioning, Geotube™ containers and gravity.

Compared to alternatives like centrifuges and belt presses, the Bishop Solids Management Solution is less complex, more energy efficient and can collect and dewater sludge at a significantly higher rate, which means projects can be completed faster and more affordably.

Ready to learn more?

Watch our brief video to see a lagoon cleanout and the advantages of the Bishop Solids Management Solution

Solids Management

Our Bishop Solids Management Solution has been used at municipal and industrial sites across Canada to collect, dewater and consolidate sludge.

Bishop Solids Management Solutions are ideal to collect and dewater virtually any type of organic or granular slurry material, including fines, silts and clays.

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Speak with an expert

Contact us today to discuss a simple, low-energy solution for your site. 

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