Gee's Chemical Dosing Technology Finds a New Home in Saudi Arabia

Gee & Company, in a joint venture with a new partner, have designed and supplied a chemical dosing system for an unusual sewerage treatment facility on the outskirts of the city park in Jeddah.

Birmingham, United Kingdom, August 23, 2010 --( Jeddah is the commercial capital of Saudi Arabia. It is the largest sea port on the Red Sea and boasts some of the wealthiest residents to be found anywhere amongst its 3.4 million strong population.

The Saudi National Water Company required a contractor to design and supply an Iron (III) Chloride sewerage treatment system for the site. The aim was to control odours, specifically for chemical dosing to neutralise the smell caused by Hydrogen Sulphide (H2S), a particularly malodorous substance which precipitates when sewage becomes anaerobic. It is toxic, corrosive and emits a very distinctive and unpleasant "rotten egg" smell. As the site is within a stone’s throw of the American Embassy and three Royal palaces a reliable solution was needed, with time a major factor.

A reliable and experienced technology partner for the supply of a dosing skid and associated control equipment was needed. The Saudi National Water Company’s technology adviser found Gee through a quick Google search which led him to the website of Gee & Company. He was immediately impressed by the case studies and accreditations on Gee's site. Gee accommodated the client’s requests and provided a cost effective and simple solution which could neutralise the odours caused. The level of knowledge displayed by Gee’s staff quickly convinced him that Gee was the only logical partner for this project.

The project required the successful treatment of 165,000 cubic metres of sewerage daily. The finished system would need to be efficient and capable of running autonomously for long periods of time with no human input. The arid, sandy environment in which it would be installed presented its own problems.

Gee's solution was to recommend the supply of three of their Signal S300 dosing pumps for the safe and precise dosing of the highly corrosive, acidic and toxic ferric chloride, a dosing skid for effective control of the dosing and custom software to regulate the whole system. The pumps themselves would be ‘tropicalised’ to help them to cope with the sand and heat in the atmosphere: in the height of summer Jeddah can regularly experience daytime temperatures up to a staggering 50 degrees Celsius.

Ferric chloride dosing would be ongoing constantly at various concentrations with greatly increased dosing required at the two peak flow times of each day. The dosing had to be precise and flexible; higher flow rates would require higher dosing strengths immediately.

Gee's solution was to control dosing via a programmable logic controller (PLC) run by project-specific software written by Gee's staff. The system they designed takes the readings from two sensors installed within the wet well. By combining the readings from an H2S sensor and from an ultrasonic level detector (to determine water volume) the skid PLC would able to determine the quantity of dissolved H2S in the well and adjust dosing accordingly in real-time.

The dosing system was housed under a sunshade to protect the equipment from the worst of the light and heat. The steel bodied skid frame was itself wrapped in GRP (glass-reinforced plastic) to offer further protection from the elements and also to protect it from the highly corrosive ferric chloride.

The PLC cycles the roles of the three S300 dosing pumps; two are assigned the roles of duty & standby pump operating at a rate of 450 litres per hour while the third acts as a boost pump running at 650 litres per hour. At regular intervals the role of each pump is reassigned in order to ensure an even usage of each. Built into the system are numerous fail-safes and alarms to alert operators to issues relating to chloride depletion, flow rate and pump failure etc.

The project was brought online and operated flawlessly as expected. Gee's Signal pumps continue to perform with their usual level of reliability and H2S levels have been successfully managed by the new system.

Gee and Company's new joint venture partners commented: “We are hoping to undertake a number of similar projects in the future and we wouldn’t hesitate to partner with Gee again thanks to their qualifications, experience and the reliability of their products.”

Nichola Balmer
01543 416060