Extending the life of sewer assets

Protecting Ageing Infrastructure

Extending the life of sewer assets

Much of the infrastructure around Australia is starting to degrade, with some reports suggesting that up to $30 billion of community assets are in poor condition and require significant renewal.

This presents challenges as Australia’s population continues to rise and citizen health and safety depends on the ongoing availability and reliability of this infrastructure. Leaking pipes, unpleasant odours, and deteriorating structural integrity can all present significant risks, including immediate danger to people. It’s essential to find a solution to this problem of ageing infrastructure, and fast.

In many cases, assets have been managed in a run-to-failure model that results in faster deterioration, leading to higher replacement and emergency response costs. This can potentially be overcome with rehabilitation and regular maintenance of existing assets.

One of the biggest challenges in sewer networks is the corrosion that occurs to both metallic and non-metallic pipes. To prolong the life of the pipes, in some cases epoxy lining has been applied, ostensibly protecting against corrosion. However, in practice, epoxy linings are problematic and often fail to deliver results. This leads to further costs for councils who then need to rectify the failed epoxy lining.

With an emphasis on creating a sustainable future for existing infrastructure, there is a clear requirement for a cost-effective, reliable, and innovative solution to this longstanding problem.

Calix has developed PROTECTA-Mag, which is a magnesium hydroxide liquid (MHL) coating that prevents corrosion by raising surface pH. The patented biostatic formula neutralises acids that cause corrosion.

Unlike epoxy coatings, PROTECTA-Mag doesn’t require flow diversion or manual entry to be applied, and it’s around five times cheaper over the lifecycle of the asset. It’s completely safe to handle, non-hazardous to humans and the environment, and non-toxic to marine and plant life.

When repairs are required, Calix can re-grout the structure with calcium aluminate cement (CAC), which is a high-strength, highly corrosion-resistant repair mortar. Combining CAC and PROTECTA-Mag results in significantly rehabilitated assets that can continue to operate successfully for decades to come.

In fact, Calix provides peace of mind that assets will be protected long into the future. This, combined with Calix’s renowned reliability, quality, and engineering, means the solution will be tailored to the customer’s needs, delivering the best possible outcome.

 

 

New formulation of PROTECTA-Mag coating proves successful at North East Water

With a constant flow from 2 other pump stations, a sewer pump station at North East Water had suffered a significant amount of acid damage, with its concrete surface visibly pitted.

Calix coated the asset with the new formulation of PROTECTA-Mag, which allows better control of hardening time and improves adherence to the concrete walls. The new formulation proved very resistant to wear in flowing / splashingconditions. The application of PROTECTA-Mag involved no confined space entry and no network shutdown. PROTECTA-Mag prevents corrosion by raising surface pH, which neutralises acids and inhibits the formation of acid-producing bacteria.

 

Before and after application, the new PROTECTA-Mag  adhering well to the walls.

Restoration of a freshwater lake using Aqua-Cal+

Taman Tasik Aman. PJ. Kuala Lumpur

 

With the recent dreadful fish kills in the Darling River, the general public are becoming starkly aware of the dangerous impact of high fertliser water run-off into water systems with little drainage or flow-through.

Calix’s AQUA-Cal+ is being tested as a key remediation treatment for a recreational lake in Kuala Lumpur that suffered fish kills, blue-green algal blooms and bad odours. We are nearly 12-months into a two-year trial with our local partners MahaChem and Thalassa Aqua.

Treatment with AQUA-Cal+ began in April, 2018, and has resulted in the elimination of the odour, and there has been no evidence of fish kills since the beginning of the project. Water quality has greatly improved, and with AQUA-Cal+ as the cornerstone of the treatment regime, the blue-green algae hasbeen controlled
while maintaining good DO (dissolved oxygen) making this lake usable once again for the local people.

In addition to treating the symptoms of an unhealthy system, AQUA-Cal+ is also being assessed on its ability to help reduce the accumulated sludge (more than 1 metre deep), via aiding bio-digestion in the lake bottom, after years of accumulation and ineffectual probiotic treatment. If the sludge digestion progresses well, AQUA-Cal+ will have made a significant contribution to the longer-term health of the lake ecosystem.

 

Lake condition – February 2018

Lake condition – January 2019

 

Watch this space for data on sludge depth readings as the project moves toward its two-year conclusion.

Hydrogen Sulphide in the heat of the Australian summer months

Highly toxic, hydrogen sulphide (H2S) gas can be produced in large quantities in animal farms, industrial plants, sewers or sewage treatment plants, and has a distinctive and unpleasant rotten egg smell causing frequent odour complaints.

H2S gas is a consequence of anaerobic mechanisms at low pH which favour sulphate reducing bacteria (SRB), and results in the generation of this poisonous “rotten egg” gas in sewers.

People can usually smell hydrogen sulphide at very low concentrations in the air, ranging from 0.0005 to 0.3 parts per million (ppm). There is no way to tell whether concentrations of hydrogen sulphide are low or high by smell alone.

In fact, very hazardous concentrations (>100ppm) will temporarily eliminate ability to smell the gas. You should not rely on your nose to evaluate possible H2S danger!

Hydrogen sulphide levels can change based on a number of factors such as fluctuations from the source, or from changes in weather patterns.

In general, low pH and high temperature tend to favour evaporation of hydrogen sulphide, putting people and infrastructure at higher risks.

Odorous emissions from wastewater treatment plants (WWTPs) can create a nuisance for surrounding neighbourhoods. As population increases, houses are being built closer to WWTPs, with buffer zones around WWTPs that offer protection from unwanted odours decreasing. In many councils around
Australia, there is a growing pressure to control odorous emissions.

Emissions of odorous compounds increase during the summer months, not only because of increased H2S volatility (evaporation) but also because of an increase in anaerobic bacterial activity, as oxygen is less soluble at higher temperatures.

It is recommended that plant operators measure H2S more regularly in the summer months, and step up odour control measures, such as dosing ACTI-Mag magnesium hydroxide, which keeps the pH high and stops the formation of H2S from dissolved sulphides.

 

Reference: https://www.tandfonline.com/doi/pdf/10.3155/1047-3289.57.11.1296

AQUA-Cal+™ is now being used in factory shrimp farms in Northern China

China, with one-fifth of the world’s population, accounts for two-thirds of the world’s reported aquaculture production.

China is one of the biggest markets in the world for shrimp with about one million metric tons grown per year. With a temperate climate and rather cold winters, Northern China cannot grow shrimp all year round as is the case in Southeast Asia.

Rising domestic demand for shrimp means factory farms must focus on increasing its yields and overall productivity. With intensive aquaculture shrimp farming comes large amounts of toxic sludge and chemical complexes like nitrite, that can be harmful to both shrimp and human health.

 

Now offering CAC and Protecta-Mag

Calix understands the importance of providing a complete repair and protection package for the entire sewer network including manholes, wet wells, and sewage treatment plants’ inlet works. Calix innovates in chemicals to offer the right sewer network, depending on the condition of the asset and each site’s specific requirements.

Calix has used Calcium Aluminate Cement (CAC) to repair failed concrete sewer assets in Tamworth Regional Council and Fraser Coast Regional Council. The scope of works included re-grouting and profiling of significantly corroded manholes and pumping stations with Calcium Aluminate (CAC) from specialty chemical company BASF.

Calix’s difference comes from the topcoat finish of PROTECTA-Mag that can be added onto the applied CAC layer, thus providing long-lasting corrosion protection of the assets.

A Pit lined with CAC and sprayed with PROTECTA-Mag for long lasting protection

 

 

 

 

 

 

 

 

A Pit lined with CAC and sprayed with PROTECTA-Mag for long lasting protection.

Acti-Mag trial at Mission Beach sewerage scheme

Mission Beach is a mixed residential and tourist area and is home to the iconic cassowary. A sewerage scheme was commissioned by Cassowary Coast Regional Council in 2006 to collect the wastewater from three constituent communities and pumped by two major stations, at Wongaling and North Mission Beach, to the Main Transfer Pump Station (MTPS). The MTPS then pumps 23km to the Tully Sewerage Treatment Plant (STP).

This sewer main suffered significant corrosion due to “rotten egg gas” (H2S) release in the drained sections. The Tully plant is designed for phosphate removal with liquid alum dosing for phosphate trimming and powered lime dosing for alkalinity and pH correction.

A trial of Calix’s ACTI-Mag Magnesium Hydroxide Liquid (MHL) dosing commenced in December 2017 with the primary objective to control septicity, odour and corrosion issues. Calix proposed additional objectives, i.e. the control of Fat, Oil & Grease (FOG) build-up, elimination of lime dosing at the Tully plant, and partial elimination of alum dosing for phosphate removal.

The trial eliminated odours by maintaining pH between 8.2 and 8.5. Pump station cleaning has been substantially reduced due to decreased FOG accumulation. The lime dosing system was prone to blockage and breakdowns, however dosing of ACTI-Mag has allowed suspension of lime dosing. Also, the dose rate has been reduced by more than 75% whilst still meeting phosphate effluent discharge limits.

AQUA-Cal+ continues to gain momentum in China

A second container of AQUA-Cal+ is on its way to Southern China following our very first shipment to China in June. China is one of the largest farmed shrimp producers in the world.

Calix looks forward to progressing AQUA-Cal+ trials there, following trial programs already underway in Vietnam, Indonesia and Thailand.

Container of AQUA-Cal+ on it's way to China

Optimising wastewater efficiency : Further Acti-Mag biogas trials to begin

In our last Newsletter, we described how our ACTI-Mag product was recently used in a Thai palm oil processing facility to increase biogas power production and improve the environmental performance of the biotreater system. Following this success, Calix has begun a trial in early August with a major Australian water utility on its biotreater-to-biogas power system. Calix is also preparing a test run on a biotreater-to-biogas power plant in the UK, run by a company with multiple biogas power plants across the country.

 

New business opportunities at a Thai palm oil plantation

With the right levels of alkalinity, it’s possible to use wastewater sludge as a powerful source of renewable energy. Biogas is created through a process of anaerobic digestion, which can convert organic matter such as that found in wastewater sludge into biogas which can be used to produce electricity. To do this effectively, it is essential to manage alkalinity and control the pH levels of the material.

Calix has completed a two-month trial of ACTI-Mag in a Thai palm oil plantation, in one of three parallel biogas plants. The trial has already yielded a 28 per cent increase in gas volume and an increase in the quality and stability of methane production to between 60 and 65 per cent of biogas. The trial is now being extended to the whole mill. There are more than 780 such mills in South East Asia, representing a significant opportunity for Calix in the region.

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