Abatement of hydrogen sulfide gas from wastewater treatment plant 2

[HAPM]

I am investigating the best method to abate hydrogen sulfide at a wastewater plant. We are looking to install a Biofilter. The Biofilter advantage is that it does not require any hazardous chemicals to operate. We used it sucessfully at one of our lift stations, however it does cost more up front. Does anyone have experiences with H2S treatment with the Biofilter or other technologies?

 

[Dwain]

You may want to look into applying Magnesium Hydroxide in your system. It is relatively inexpensive and it eliminates odor problems.

 

[sandra]

I would like to know abou the advantages to use nitrate solutions to solve the sulfide production problems? I need to knoW procedures and enterprise that do the addition of calcium or sodium nitrate.

 

[mikolay]

Have you checked for H2S in your sewers lately? We are experiencing excess H2S in our interceptor sewer which is corroding the crown of the RCP. We are trying a nitrate salt, Bioxide, to suppress the H2S and it seems to be working well. We pump about 20 gpd into a wet well in the upstream lift station which gives us about a 5 ppm residual going into the interceptor sewer. [sig][/sig]

 

[Ginger]

I am currently designing a large sewage gravity filled interceptor sewer (10 km long at 3.6m internal diameter). We have the potential to generate large volumes of hydrogen sulphide which can be expelled at a high rate when a storm surge advances along the sewer.

Our solution to treat the gas is to use activated carbon. essentially, the sewer vent passes through a "dustbin" (or garbage can for my US cousins) filled with IVP-type activated carbon. This is able to remove 98% of H2S at a relative humidity of 100% with a flow of 0.45 cubic metres per second. The carbon has a finite lifespan but replacement is simple. You lift the lid off the bin, hoover out the used up carbon and replace it with fresh carbon.

Regards [sig]<p>Andy Machon<br><a href=mailto:Andy@machona.freeserve.co.uk>Andy@machona.freeserve.co.uk</a><br><a href= > </a><br> [/sig]

 

[HAPM]

Ginger,

Can you tell me what's the approximate changeout for the carbon unit and the material cost?

 

[Ginger]

hapm

Sorry for delay in replying, my 10 year old son inverted a cup of tea into the keyboard!! It has taken me a few days to replace the keys.

I will need to consult my data at the office but I think the prices are affected locally so you would get a better handle on the prie by approaching a carbon supplier close to you. For the flows we have I believe that the 1.5m diameter, 2m high nbin will last about one year on our contract. I will try to get the prices for tomorrow.



Andy Machon
Andy@machona.freeserve.co.uk

 

[Ginger]

hapm

OK, The units we have installed are 2.22m diameter by 1.765m high and look like black polyester/polypropylene trash cans with a 250mm diameter inlet and outlet.

From our suppliers literature:- The unit can purify air streams of up to 1500 cubic metres per hour by activated carbon adsorption when using IVP carbon. The pressure drop to acieve this is 3000 Pascals. There are 510 kg of carbon pellets in the unit which can remove up to 60% of its own weight in pollutants.

The rate of carbon replacement is entirely dependant on the amount of polluted gas you put through the unit (but you could work this backwards from 60% of 510kg and relate this to your polluted gas H2S content to get a rough idea I suppose).
Your carbon supplier should be able to visit site and test the carbon you have to determine what life it has left.

A new unit of this size is about £5000, but I don't have the figures for replacement carbon

Hope this helps

Regards

Andy Machon
Andy@machona.freeserve.co.uk

 

[HAPM]

Ginger thanks.

 

[AquaDoc]

I know of a facility that uses ferric chloride injection upstream to control HS formation/release. If interested, I can get further details (dosage levels, contact names/numbers, etc.).

 

[HAPM]

I'll check on your ferric chloride and may followup with you later if that's ok with you. Thanks.

 

Does anyone know of a standard method or emissions factor for calculating h2s emissions from wastewater (lagoons, etc.) -- or especially anyone who has expertise in this area? Thanks

 

[chemist]

Have you ever thought designing the system in HDPE?

 

[ema]

We have constructed a ferrous sulphate dosing unit to eliminate problems occuring at generators using methane. It was located at the main inlet of the treatment plant. But i remember we had long discussions about where to locate the unit. Ferrous sulphate is a by pruduct of steel indusry and it was very cheap in the area where the plant was located. Since the plant has 700,000 m3/day capacity, we used ferrous sulphate instead of ferric chloride. If interested, I can give further details.

 

[marktb]

Are you sure of your 500 ppm H2S. This will make a very corrosive gas/solution when mixed with water. I had all sorts of trouble when H2S levels were above 100 ppm with a Dual Fuel Diesel Engine with valves pipework and gas compressors failing due to this problem.

 

[HAPM]

I have installed a &quot;biofilter&quot; system which extracts H2S from contaminated air by converting it into elemental sulfur. The initial cost is relatively high (approx. $700,000) but the long term operating cost is low. The filter media consists of trays filled with compost like material containing microbial flora that break down H2S. The elemental sulfur accumulates in the compost. The compost is replaced as the sulfur builds up.

 

[MadChemist]

You could try nutriox, we use it in terminal pumping stations in the UK.

 

[stanier]

Biofilters have been installed by Bovis Lend Lease on plants in Australaia and New Zealand. Dersign has been by CH2MHill. They are fine for H2S but are challenged if you have ammonia. So a lime stabilisation plant would be challenged.

Key issue is to cover the unit to prevent drenching by rain water but provide sprays so you can control moisture. Apart from that the costs to run are minimal once the right mix of soil is establish.

For smaller sysytems Cleanteq in Melbourne manufature containorised units that are fully equipped. Useful for small towns.

 

[nak217536]

Hi, I am involved in the operations of a waste water treatment works which handles 90 % domestic sewage and 10 % treated industrial effluent. At present the foul odours are treated with a caustic scrubber system. I want to know the impact on the aeration basins if the foul air is injected into the aeration basins. Volume of air will be 100000 m3/h with an average 400 ppm h2s. volume of the aeration basins will be 15000 m3 with an MLSS of 2500 mg/l.

 

[Wikki]

H2S is only one of the many facets of Digester gas quality. A simple answer cannot be given to the question on removal of H2S without addressing all gas quality issues especially if burning in a gas engine. Major reduction in O/M costs (approaching natural gas O&M) can be achieved with a properly engineered solution.

This typically would encompass dehumidification, dust removal, H2S reduction, Siloxane removal, pressure management and temperature management.

Some engine suppliers don't necessarily make this obvious as it is not their core business to provide the technology or expertise in this area and they are happy to rebuild engines and sell more parts.

Feel free to contact me if you want to know more.
email warwick.cutfield@meritec.org