Surface World April 2019 Surface World April 2019 - Page 52

WATER & EFFLUENT TREATMENT pH Neutralisation System from above When the waste water has been pH corrected, the customer requested that this is discharged into a cascading sump arrangement via an outlet on the tank. The customer specified that the outlet was via a 3” flanged connection and the location of this agreed during the design phase of the project. To ensure compatibility with the customer’s process, the system was also supplied with the counter to the flange for simple on-site installation. that the pH neutralisation system can return the neutralised effluent to drain through a cascading sump arrangement. Pallet / Skid Mounted pH Neutralisation System Our customer’s core preference was for a complete solution to their pH neutralisation which could easily be positioned into place and simply integrated into their existing processes, including drawing the waste water up into a treatment tank from a sump. From a practical perspective, in the future, the pH neutralisation system might need to be relocated, cleaned or inspected. For this reason, we included a foot mounted drain valve allowing the customer to empty the tank when required. We provided our customer with a single fabricated solution which could be lifted using the skids of a fork lift truck for easy transportation to site, and so that it could be simply manoeuvred to the desired site location. Control Panel The fabricated solution was destined to be located outside. To protect the instruments from the environment all the fabricated enclosures containing the control panel, instruments, air operated double diaphragm pumps and the chemical dosing pumps were provided with transparent covers to protect them from the elements. pH Correction Pumps All the wired connections and external electrical items such as the top mounted alarm beacon and all electrical glands have been supplied to IP65 specification, which ensures that they are suitable to be located outside. The pH correction tank was fabricated in chemically resistant polypropylene and also mounted onto our skid mounting area - allowing the whole unit to be lifted from a fork lift as well easily manoeuvred for final positioning. Access to the tank is via a half removable lid complete with a mixer bridge to support the high speed mixer. The enclosure containing the control panel was fabricated as a separate chamber isolating it from the lower enclosure, which contains the duty & assist air operated double diaphragm transfer pumps. The chemical containers were located in another enclosure located at the opposite end of the skid mounted unit. This skid mounted enclosure includes 2 separate bunded areas - each designed to contain a 25 litre chemical container with a capacity of ~35 litres - to contain the contents of each of the chemical containers in the event of a spill or leak. The hoses connecting the air operated transfer pumps and the chemical dosing pumps have been supplied as double confined dosing tube to ensure containment in the event of the tubing becoming compromised. Control Panel The control panel is mounted into the front enclosure, behind a removable transparent covering. This pH neutralisation system uses a number of inputs to fully automate the treatment of pH correction of the waste water with very little human involvement required. The waste water is transferred to the treatment tanks using the air operated double diaphragm pumps. As the volume of waste water generated can vary depending on the processes occurring in the customer’s factory, two air operated double diaphragm pumps have been fitted; one acting as a duty transfer pump and the second acting as an assist. The duty and assist pumps mean that during normal operation, the duty pump has the flow rate to transfer enough volume of waste water to the treatment tank to ensure it can be corrected. As the processes used by our customer vary, the amount of waste-water generated can also vary. To cope with increased volumes, a second air operated double diaphragm pump has been fitted as an assist. This potentially doubles the amount of waste water that can be transferred to the treatment tank, preventing the sump from flooding in times of increased production. The duty transfer pump and assist transfer pump are controlled based on the level in the sump. By using low level float switches located in the sump, at a high level, the duty pump is called to transfer the waste water. If the level continues to rise to the second high level (high-high-level), then the assist pump is engaged to reduce the volume of waste water in the sump and transfer it for treatment. Each air operated double diaphragm pump uses an air feed line which passes through a solenoid valve. The solenoid valve is controlled from a level controller within the CONTINUED ON PAGE 52 50 APRIL 2019 read online: