H2S stinks – and not only for those who stuck smelling it. Complaints concerning hydrogen sulfide odors can cause penalties, citations, or worse for the facilities involved. One way users can prevent these complaints is to monitor H2S levels so that they can proactively work to keep the levels below the odor threshold.
Monitoring H2S Levels
A monitoring system or low level analyzer is required to monitor H2S levels before they turn into nuisance odors. In the US, most permits need a fence-line upper limit of 30 ppb (parts per billion) H2S. Even though this level is below the most noticeable levels of hydrogen sulfide (3000-5000 ppb or 3 to 5 ppm), most people are very sensitive that they can even smell as little as 10 ppb (0.01 ppm). Therefore, systems with high lower detection limits will not be able to help users here.
Recently, Thames Water improved and expanded their network of low-level H2S monitors at Mogden Sewage Treatment Works located in the UK. This was carried out as part of major site improvement that would increase capacity and help the facility meet stringent regulations.
Mogden Sewage Treatment Works
Mogden Sewage Treatment Works, J.L.
Built between 1931 and 1935, Mogden Sewage Treatment Works is the second largest sewage treatment plant in the UK. It serves around 2.1 million people and covers an area of 55 hectares (0.21 square miles), and some of the wastewater has traveled more than 20 miles by the time it reaches Mogden. More than half of the power used by the plant is renewable energy which has been produced on site as part of the sewage treatment process.
Final Sedimentation at Mogden Sewage Treatment Works, J.L.
Last year, Thames Water requested ABLE Instruments, Jerome’s distributor in the UK, to help upgrade the boundary monitoring network at Mogden, as part of a more than $180 million enhancement to the site. The project was completely designed to extend sewage capacity by 50% at Mogden. Since the capacity increase would certainly mean an increase in H2S, Thames Water determined that an upgrade was in order.
The improved H2S boundary monitoring system would help ensure that the recently upgraded sewage treatment works was able to control the increased level of sewage without increasing nuisance odors in the surrounding region. It was just a matter of expanding the network as several Jerome analyzers have already in place around the facility. Thames Water bought 15 additional Jerome gold film hydrogen sulfide analyzers, bringing their total to almost 30, and started installing them all over the works.
Jerome® H2S Analyzers
Jerome gold film hydrogen sulfide analyzers are easy to use, reliable, and rugged, and they can detect as little as 3 ppb of H2S in air. For more than 35 years, this technology has been proven both in the lab and in the field, and is actively being used by several regulatory agencies and waste management, landfill, and water treatment facilities across the world.
Jerome® 651 Fixed Point H2S Monitoring Solution
Jerome® 651 Hydrogen Sulfide Monitoring System
One of the first decisions needs to be made while planning odor monitoring solution is whether to employ hand-held instruments, fixed point instruments, or both. Thames Water decided to use a combination at the Mogden facility. The Jerome 651 (the above figure) is a fixed point monitoring solution. It is designed to offer long-term and continuous monitoring even in severe weather conditions. The Jerome 651 system can be fixed on a fence, pole, or even a wall and multiple units can be connected to form a perimeter monitoring system. It has a detection range of 3 ppb to 50 ppm and includes programmable high limit alarms that can send alert emails if the H2S levels ever increase above a set level.
The attached weather station offers information on wind direction and speed so that users can more accurately identify from where an odor is coming. In addition, the Jerome 631 analyzer inside the box can be removed and used on its own to sweep an area as well as locate the source of a hydrogen sulfide hotspot.
Jerome® J605 Portable H2S Analyzer
Jerome® J605 Hand-Held Hydrogen Sulfide Analyzer
The Jerome J605 is the most advanced portable H2S analyzer. It has a lower detection limit of 3 ppb with a 20 ppt (parts per trillion) resolution, providing improved accuracy in the single figure ppb area which is very beneficial for monitoring nuisance odor because the odor limit for some people is as little as 10 ppb. The J605 hand-held hydrogen sulfide analyzer is lightweight and features an ergonomically designed handle for better portability. It has a battery life of 18 hours, can store up to 20,000 data points, and has automated sampling and field regeneration functions, making it perfect for long term, short term, and even unattended H2S monitoring.
Success at Mogden
Besides redesigning the western embankment, Thames Water enhanced the landscape to west of the site to put up the new equipment installations that would increase the operation at Mogden Sewage Treatment Works. This helped reduce sewage overflow during heavy rain and assisted Thames Water to meet stringent quality standards for the waste matter they discharge. In combination with the expanded network of Jerome H2S monitors, the modifications are helping to decrease odor at and around the site.
Due to the success of the Jerome instruments installed at Mogden Sewage Treatment Works, Thames Water has recently bought 6 more analyzers to help reshape odor boundaries at its Acton site, which is currently undergoing a similar expansion.
This information has been sourced, reviewed and adapted from materials provided by AMETEK Brookfield Arizona
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