Case Studies

Effective control of extreme hydrogen sulphide emissions from a sewerage transportation system.

The Background

The sewerage transportation system in the South Western region of Lake Macquarie in New South Wales comprises a complex network of gravity mains and several pump stations. The large number of pump stations and cumulative retention time of the sewage flowing in the system, results in the generation of septic conditions and susbequent hydrogen sulphide emissions at a number of points in the system.

The Challenge

One particular site, Maintenance Hole (MH) No. 1935 in the suburb of Windemere Park, was emitting extreme levels of hydrogen sulphide with peaks of >500 ppm and an average of 140 ppm. This caused an odour nuisance to surrounding residences, an OHS issue for the sewerage system operator, and severe concrete corrosion to the MH.

MH 1935 is the discharge point for a common rising main that carries the combined flows from three upstream pump stations. These three pump stations, in turn, have a network of upstream pump stations.

The Solution

OCS was engaged to design, install and operate an automated ferrous chloride dosing system to control dissolved sulphides in the rising main and subsequently, control hydrogen sulphide gas emissions from MH 1935.

OCS installed a dosing facility on the common rising main, upstream of the MH. The facility doses ferrous chloride directly into the rising main. The operation of the dosing pump is controlled via telemetry signals from the three upstream pump stations. Each time a sewage pump operates, the dosing pump injects ferrous chloride at a dosing rate to suit the particular sewer pump that is operating. The dosing pump can also accommodate multiple sewage pumps operating simultaneously. The dosing pump is programmed to take into account anomalies such as wet weather flow conditions or a malfunctioning sewage pump.

The Outcome

The dosing facility has achieved a consistent 95% reduction in peak hydrogen sulphide emissions (down to 30 ppm) and a consistent 99% reduction in average hydrogen sulphide emissions (down to 1.4 ppm) at MH 1935. This result is particularly pleasing considering the highly turbulent flow conditions in the MH. Dissolved sulphides are maintained at <1 mg/l.

Benefits Summary

• The OCS ferrous chloride dosing system has successfully addressed all three issues:
  • odour complaints
  • OHS hazards
  • MH corrosion
• No action is required  by the customer as OCS provides a full operation and maintenance service to the dosing facility and regular hydrogen sulphide gas monitoring and liquid sampling.

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Yates fertiliser plant has successfully implemented an immediate solution to a long term odour problem.

The Challenge

Yates operates a large fertiliser plant in Wyee, New South Wales. Their process produces odour emissions which are discharged from the site after first passing through a chemical scrubber and biofilter, then vented via a large stack. The chemical scrubber and biofilter have been in service for many years, but Yates wanted to enhance the protection against odour emissions. The air discharge rates are significant, ranging from 30,000 to 70,000 cubic metres per hour.

Odour Control Systems is currently working with Yates to run a pilot trial to prove the efficacy of a new type of biofilter - FiltaOdor^TM. However, Yates needed an immediate solution to effectively control odours until the new biofilter technology can be successfully trialled and installed.

The Solution

OCS installed a system to deliver an odour neutralising agent directly into the foul air ducting. The system entailed solution storage, pump and control unit, and a series of injection nozzles inserted into the foul air ducting. The odour neutralising agent selected was AirSolution 9304 (Phantom 4).

The Outcome

The odour neutralising system installed by OCS provided immediate, effective odour control for Yates.

Benefits Summary

• The plant was able to continue normal operation without causing odour nuisance to the surrounding areas.
• With odours effectively controlled, Yates now has time to carry out a thorough biofilter pilot trial and properly evaluate the results without the need to fast-track the process.
• When the new biofilter is fully operational, the odour neutralising system can remain in place as a back-up or standby unit that can be immediately deployed in the event of any problems with the biofilter.

Contact

David King
Site Manager - Yates Wyee
Phone: +61 2 4357 2380
Mobile: +61 439 557 425
Email: david.king@yates.com.au

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Challenge

A research lab in Toronto, Canada had an opportunity to test our Ultimate Auto-Fresh 530 product, specifically designed to eliminate autoclave odours.

Solution

The product was placed in an autoclave where all petrie dishes used in the lab were sterilised twice a day. The dosage rate that effectively eliminated the foul odours was 1-2 ml of product per 12 litres autoclave capacity. In the test report they wrote, "Your product was very effective at eliminating the odours we normally have to deal with."

The product was also tested at a pharmaceutical company in Montreal. They used the autoclave to sterilise all medical wastes collected at the facility. The duration of sterilisation at temperatures above 100^oC was from 45 minutes to 1 hour, and the duration of cooling was the same. They followed our initial recommendation and used 4 ml of product per 12 litres of autoclave capacity.

The product was poured into an aluminium dish and placed on top of the waste piles loaded into the autoclave. When the autoclave was opened after the cycle, there was no bad odour at all and the product had been used up completely without any residue left.

Outcome

Ultimate Auto-Fresh 530 very effectively eliminated strong, unpleasant odours produced by wastes and the sterilisation process as well.

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Background

Scalabrini Retirement Village in Sydney, New South Wales has an aerobic digestion unit that is followed by a run-off lagoon fed from both the residential units and hostel accommodation sewerage and wastewater. Water from the lagoon is used for watering around the site.

Upon initial inspection in July 1999, it was noted that the site had been neglected for a number of years, resulting in the aerobic digestion process failing and becoming anaerobic, and producing foul odours. Also observed were high levels of BOD, ammonia, phosphorous and suspended solids exceeding the legal limits for discharge under their EPA license. The digestion unit has a holding capacity of approximately 30,000 litres. The run-off lagoon has a capacity of approximately 350,000 litres. Main sewerage sump pump - 7,000 litres per hour, small tank sewerage sump pump - 12,000 litres per hour.

Challenge

There were two primary objectives with the use of BioStreme 201. Firstly to assist in bringing the aerobic digester back into line and to bring ammonia, BOD, phosphorous, dissolved oxygen and suspended solids levels back to within legal and EPA license agreement limits, and secondly, to suppress unpleasant odours from the process.

Solution

Treatment has been carried out using BioStreme 201 which is added via chemical dosing pumps into both the small sewerage tank sump well and the main sewerage tank sump well at a rate of 7ppm in each. As well as treating the system with BioStreme 201, all aerator nozzles were replaced.

Outcome

Prior to the introduction of BioStreme 201 there were noticeably serious problems with odours. The allowable EPA limits for discharge had been exceeded, and as mentioned, the biological unit had not been serviced for a number of years. Within five to ten days of introducing the BioStreme 201 treatment program there was little to no apparent odour coming from either the biological unit or the lagoon. The ammonia, BOD, total grease, phosphorous and suspended solids levels also decreased until they reached a plateau. Treatment has been ongoing for more than ten years with continued success. The client continues to meet discharge requirements and odours are no longer a problem

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Background

A turkey processing facility in Ontario, Canada processes 40,000 turkeys per year. This facility uses minimal amounts of potable water in their processing activities and produces wastewater with very high levels of BOD, suspended solids, oils and fats. The wastewater produced from this facility is stored in a 2,000 gallon holding tank for up to six months before pump out.

Malodours from the tank have been an ongoing cause of complaints from employees and the haulage company was considering not removing the waste due to the extreme odour.

Challenge

With odours migrating off the farm causing complaints from neighbours, and the haulage company potentially stopping pick up of the material, HLS Ecolo was engaged to develop an effective odour control program.

Solution

A program involving weekly applications of a diluted BioStreme 201 solution was developed for this facility. The operators pre-mix the concentrated BioStreme 201 product with water and pour this solution directly into the holding tank once a week. In addition to the treatment of the holding tank, we also implemented the washdown of an adjacent waste collection room which drains directly into the holding tank, using a dilute solution of BioStreme 111 contact deodouriser.

Outcome

The operators of the facility reported that the application of the BioStreme products have proven to be very effective at reducing the malodours from the holding tank and collection room. In addition, the haulage company commented on the tremendous decrease in odours and is continuing to haul the product due to the odour reduction.

The operator is continuing with the BioStreme odour control program and has stated:

"BioStreme works very well and is also very cost effective when compared with other products we have tried."

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Background

Hopewood Health Resort is located at Wallacia in the Blue Mountains region of New South Wales. Approximately 100 guests are accommodated on-site and attend various natural health programs. The calculated daily flow of effluent from the retreat is 23,000 litres.

All effluent is collected in a balance tank, then dosed through a Blivet Sewerage Treatment Plant. This is a BMS Aerator System. The treated effluent is disinfected with chlorine and discharged to the disposal area.

Challenge

In October 2004, HLS Ecolo was notified that the plant was giving off an unpleasant odour and that sludge was accumulating faster than expected. At that time, they required a load of sludge be removed every 12 weeks at a cost of approximately $2,000.

Solution

After visiting the plant, it was recognised that all of the clients at the Retreat were vegetarian, and therefore all meals were vegetarian. This diet was causing a lot of the associated problems with bacteria.

It was decided to dose the system with BioStreme 201 via the inlet drain at the rate of 3ppm (70ml daily). This dosing has continued to date.

Outcome

Odours left the plant within days and the health of the bacteria in the system improved dramatically. The accumulation of sludge has been reduced and there is at least one less pump out required annually, saving $2,000. The operator reports that there has been no further problems associated with the system since they commenced using BioStreme 201. The total annual usage of BioStreme 201 in this system is 25 litres.

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Background

A poultry processing facility in Ontario, Canada processes 10,000 chickens per week. This facility uses large amounts of potable water in their processing activities and produces wastewater with high levels of BOD, suspended solids, oils and fats.

The wastewater produced from this facility is transferred to a series of on-site, surface aerated lagoons where solids settle and water gradually evaporates in the treatment process. Malodours from the lagoons have been an ongoing cause of complaints from local residents and businesses.

Challenge

HLS Ecolo was engaged to propose a BioStreme 201 wastewater treatment program to reduce malodours from the lagoons.

Solution

BioStreme 201 was diluted 100:1 and applied using a water cannon on a weekly basis, 10 litres on Monday and 10 litres on Wednesday. The diluted product is applied to the surface of the lagoon and mixed with the existing surface aerators.

Outcome

The operators of the facility have reported that BioStreme 201 has been very effective at reducing malodours from the wastewater lagoons and they are continuing with the program.

"BioStreme 201 works very well and is also very cost effective compared with other products we have used. We have been using BioStreme 201 to keep our lagoons in tip-top working order and keeping us well within Ministry of Environment compliance requirements."

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