Reduced H2S generation within the catchment.
Signiﬁcant reduction of FOGs within the catchment.
Save on multiple chemical purchasing and asset maintenance costs.
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.
Fats, oils and grease can build up and become what are called fatbergs.
Fatbergs are caused when oils and fats are tipped down the drain and congeal with other products, including so-called ﬂushable wet wipes.
While each state has their own utility providers, there were at least 360 blockages caused by fatbergs in sewers serviced by QUU — which take in the Brisbane area and four other local councils.
That’s out of a total of 3,500 blockages in QUU sewer pipes that together cost $1.2 million to clear. Fatbergs also caused almost 250 sewage overﬂows.
But fats, oils and grease also play an important role in wastewater treatment plants, particularly those that capture biogas to generate electrical and thermal energy.
ACTI-Mag is a concentrated and stabilised suspension of magnesium hydroxide also known as milk of magnesia. An inorganic compound with the chemical formula Mg(OH)2.
Highly ﬂuid, ACTI-Mag has proven to ﬂow easily in most dosing systems. With a higher neutralising value per dry kilo when compared with caustic and lime and being signiﬁcantly safer than other traditional alkalis, ACTI-Mag is a very cost competitive option for hydrogen sulphide gas (H2S) control in sewers and industrial waste treatment as well as for several other applications including phosphorus and nitrogen removal from wastewater.
Calix’s ACTI-Mag has several advantages over other generic MHLs.
RESULTS OF SECONDARY OBJECTIVES AND OTHER BENEFITS OF ACTI-Mag
Magnesium Ammonium Phosphate (MAP), commonly known as Struvite, is a crystalline precipitate of Magnesium, Ammonia, and Phosphate.
Mg²+ + NH4+ + PO4³- + H2O = Mg.NH4.PO4.6H2O (s)
Struvite forms in pipe bends due to pressure differential in the ﬂow. This will lead to a solid precipitate creating blockages and restricting ﬂow.
The advantage of dosing ACTI-Mag is that it precipitates ammonia and phosphate directly in the sludge and stops struvite forming on key infrastructure.
ACTI-Mag has a higher neutralising value per kilo when compared with caustic while being significantly safer to handle than other traditional alkalis, making it a very safe
and cost competitive option for hydrogen sulphide gas (H2S) control in sewers.