BHP Billiton Mitsubishi Alliance (BMA) engaged Dowdens Pumping & Water Treatment [Brisbane] to design, manufacture, install & commission a 200kL / day Sewage Treatment Plant (STP) which included three pump stations and a specialised central control room at their Saraji Coal Mine, located 60km southeast of Moranbah and 200km southwest of Mackay in the Bowen Basin, Central Queensland.
Saraji Coal Mine has coal reserves amounting to 648 million tonnes of coking coal, one of the largest coal reserves in Asia and the world. The mine has an annual production capacity of 5 million tonnes, utilising open-cast extraction methods with a total of 11 coal seams.
Saraji Coal Mine required a new STP due to the existing onsite plant failing to meet release limits and becoming unsafe to operate. Dowdens Brisbane designed a new STP that incorporated the innovative MIRACELL™ Rotating Biological Contactors (RBC). RBC technology is a type of sewage treatment process in which disks that are connected to a shaft are rotated at a very low speed (3.7 rpm) by means of a motor which is equipped with a reduction gear. The MIRACELL™ RBCs are designed such that 40% of the disks remain in the wastewater.
As the discs rotate contact with the wastewater causes turbulence and consequently aeration. As a result of this repetitive process, organisms accumulate on the discs. The organisms receive the necessary oxygen from the air during the rotation of the discs and consume the pollutants existing in the wastewater, converting them to carbon dioxide and water in a totally natural way. The treated water discharged from any MIRACELL™ STP is guaranteed to meet the most stringent discharge standards and may be used for dust suppression, irrigation or directly discharged to a waterway subject to Environmental Authority approval.
MIRACELL™ Sewage Treatment Plants are fully automatic, utilising modular designed RBCs specifically designed for sewage treatment applications in capacities ranging from 50 to 20,000 Equivalent People (treatment of between 10m³ up to 4000m³ per day). Representing the ultimate in sewage treatment systems, a MIRACELL™ STP consumes as little as one fifth of the electricity and requires as little as one third of the space of its competitors based on the activated sludge technology.
Dowdens Pumping & Water Treatment are proud to hold Australia-wide exclusive distribution rights for MIRACELL™ STPs - these systems are most preferred by customers who clearly understand the economic value in purchasing an expertly designed and professionally built system. Offering a comprehensive range of innovative MIRACELL™ STPs, Dowdens provide an all-in-one service approach to each project. From project inception through to final commissioning, our team of industry trained engineers, draftsmen, project managers, sales staff and tradespeople including electricians, fitters, polywelders and plumbers will have you covered!
Dowdens Pumping & Water Treatment [Brisbane] were successful in the initial tendering process as we could deliver a complete turnkey Sewage Treatment Plant solution within the limited project budget, whilst also meeting all of BMA's specifications.
The standalone Sewage Treatment Plant Dowdens Brisbane supplied BMA provided an expertly-designed system that allowed them to meet their regulatory requirements, whilst providing a reliable, easily operated and maintained system. The new Saraji MIRACELL™ STP needed to accommodate the total mine site workforce of 645 Equivalent Persons (EP). Dowdens have designed the Saraji MIRACELL™ STP to treat up to five times the Average Dry Weather Flow rate of 40 kL/day - meaning the STP has the capacity to easily process and treat up to 200kL/day.
The Saraji MIRACELL™ STP and three fibreglass pump stations have been designed to capture and treat all waste influent (both Sewage & Grey Water) from the entire mine site and deliver it to the STP for processing. The system's design had to not only deliver the desired treated effluent quality but also incorporate strict safety requirements while adhering to the Queensland Government's Department of Environment and Heritage Protection stringent environmental conditions.
The Saraji MIRACELL™ STP includes a pH correction system to allow for pH correction. The pH correction dosing system comprises a pH correction chemical storage tank and a dosing pump. An Electromagnetic flow meter installed on the inlet of the chlorine contact tank automatically adjusts the chemical dosing rate based on the incoming treated effluent volume. This ensures the pH on the outlet of chlorine contact tank is always within the range of pH 6-9.
The Saraji MIRACELL™ STP is also equipped with a remote monitoring feature that enables the Saraji Mine operators to check the status of the STP from anywhere in Australia via portable devices such as smartphones or tablets.
Dowdens Pumping & Water Treatment [Brisbane] design philosophy for this project was: Cost Effectiveness - Current Best Practice - Ease of Installation - Simple Plant Operation - Plant Reliability & Reduced Maintenance.
Beginning in June, running through to October 2015 the Saraji Mine MIRACELL™ STP was delivered on time and within budget. Extensive onsite works were undertaken by Dowdens Pumping & Water Treatment to enable the new system to be properly housed and connected to existing site, power and pipework infrastructure. The STPs construction works involved (but was not limited to) civil, electrical, mechanical, hydraulic and structural works utilising Dowdens Infield Service / Installation Crew, Supervisors, Engineers and Project Management.
Key Project Milestones & System Components are listed below: