water pollution

Who remembers the Chicago "Sanitary" and ship canal? Take and reverse the flow of the Chicago river to send the urban shit down state, and on to the Mississippi River. Sounds like a good idea to keep the lake front "clean".

People will try hard not to shit in their own houses, but hey have no problem shitting in someone else's.

Icarus

 

I like that no nonsense writing style!! I saw that canal.

 

That doesn't add up. I have no idea how Adelaide handles their wastewater treatment, as I have never had any such contracts in Australia. However, the following general and manufacturere specific links should provide more information on meeting solids target zones

Sludge Drying of Waste Water & Potable Water

Keppel Seghers - Sludge treatment

Municipal Residuals Management & Biosolids Reduction Municipal Residuals Management & Biosolids Reduction

Well, technically, the use of digesters onsite with turbine or recipricating power run off methane, using the waste heat to preheat the solids, is already considered co-gen or CHP (Combined Heat and Power)

Usually all that is flared is sour gas - say H2S - that can have a detrimental effect on turbine GG sections: the H2S can cause significant corrosion issues in the GG

Typically, using an aero-derivative turbofan in CHP is ideal: aero-derivatives are well understood, easy to maintain, and designed to last a long time; the very high exhaust heat stream is ideal to run recovery/flash boilers, and to preheat stuff like sludge; and, turbofans are adapted to a wide range of input fuels

If the primary concern is wet, sour gas, a recipricating engine is a far better choice. For example, a Waukesha V-16 can be custom built to operate off wet, sour gas with minimal effect on engine life. A lot of the conventional and synthetic blend industrial oils are designed to minimise negative effects from sour wet gas

I would very much recommend an industrial recipricating engine over a turbofan if there is the possibility of running sour wet gas

 

It's a no-brainer to an engineer. Problem is, engineers usually have little influence over project funding. Typically, an Old Boys Club in local and regional politics will determine projects to fund

Mention to a barely literate Old Boys Club member that you can turn s*** into energy, and they will not believe you. Don't even bother with P&ID's (Process and Instrumentation Diagram), fancy Calculus, or other hair-brained schemes, as they will run away screaming from you

Actually, if it was entirely up the Old Boys Club, we'd still be dumping raw s*** into rivers, lakes, and oceans

 

well, they HAVE determined that dumping raw sewage saves them a penny per million gallons which is all they needed to hear to be on board with that!!

 

Um ... good point. Never underestimate the ignorance of the Old Boys Club

 

Unfortunately, that's how just about every facet of society works. During my time at the Univerisity of Arizona I learned that Science has its own "Good Ole Boy" networks. The Old Boys are everywhere, unfortunately. Sometimes you benefit, most of the time you don't.

 

You're absolutely right

 

well the prime example of the old boy network has to be the bush administration denial of global climate change

 

Thanks Jayman, I used the wrong term, I mean't base load mains generators or they could even do peak power generation and pick up the premium electricity price at peak load if they had enough gas storage.

One of the buildings I worked in had a co-generation plant in the ground floor, it had 2 natural gas turbines to generate electricity and the waste heat was used to run the airconditioning system and heat water for the building. I'm not sure how successful it was, the department is looking at moving out of that building now, a few years after the instalation of the system. It was installed to reduce greenhouse gas emissions.

I have no idea why they say 3 years on their web site to dry the sludge, maybe it is just left to dry, not sure, or it could be a misprint, maybe it's 3 weeks or 3 months?
I have seen that some of the plants here use reciprocating engines, they may use the lower quality gas. Most rubbish tips have generator plants run from the landfill gas.

 

The Good Ole boy mentality is quite alive and well in science. Who gets funding is often a matter of who you are. Got friends at the NSF? You're more likely to get grant proposals funded. That's just human nature. People like to help their friends and fund programs that reinforce their POV. Obviously, this sort of mentality is ubiquitous, science (or really, I should say Academia) is one of two places I've witnessed it in action. The military is the other arena where I've seen it in action.

 

landfill gas in another nice niche resource. Here in the states it's getting utilised more and more. A company called Waste Management (which is a MASSIVE company) currently is producing over 700MW at a number of land fill sites (that's cumulative, not at each site). Most of them seems to be <10 MW facilities though I have seen a few 30+MW ones.

 

Back in the stone ages (that would be about 1970) I took a class at UCLA given by a visiting professor. His specialty was ecology, which at the time was a pretty hairy fairy topic. He took the class on a tour of a water treatment plant, where we learned how they turned this awful waste into pure water. The water treatment guy was truly ecstatic about how effective his plant was in treating the water. I asked why we didn't just reuse the treated water since it was so pure. He said that scientifically it was pure, but the public just wasn't ready to accept treated water.

After the formal presentation, the professor led us to the outflow point of the plant. After beating through some bushes, we came upon a rusty chain link fence with a sign "DANGER, RECYCLED WATER". The water had about 4 inches of foam on top. The area upstream of the outlet just looked like an ordinary stream. At the outlet and below, there was an overgrowth of algae and other green muck.

The professor really wanted to upgrade his "visiting" status to whatever the next grade is, but he didn't play along with the system well enough. He was replaced the next year with a non-descript mouthpiece for the status quo. Today what he had to say seems rather tame, but it took 40 years (and his job) to reach today's point. UCLA is generally known as a fairly forward thinking institution, and yet it excluded a free thinker just as blatantly as the Bush administration.

 

I think it's important to find that fine line between aloofness and nice person kissing. That worked for my career

 

Odd how I only just received notification of this post

Yes, it's a bit of a challenge to balance peak/offpeak with onsite gas storage. Typically, you will attempt to design the system to meet a specific goal, eg offpeak only, or peak only. Usually a faster ROI if you design to meet a portion of peak need

Eg: say your peak power cost is 1100-1500 each day. A design using onsite storage, and appropriate sizing of the CHP system, will be made to provide power at least from 1100-1500, with offpeak loads partially met by mains

A well integrated CHP system will be able to meet the vast majority of the facility power and heat/steam needs, ensuring quick ROI

That is the typical application for CHP. I'd be very surprised to hear they are giving up on it, unless a gross error was made in design. In most of the North American market, a 3-5 year ROI is typical

Even futuristic technollgies are gaining acceptence. Consider a datacenter or other facility with the need for uninterruptible power. Several megawatts of UPS are very wasteful of power, and require high maintenance. Flywheel UPS's are gaining wider acceptance due to much better efficiencies and lower maintenance.

I went to the website and they claim 3 years. Could be they are using air drying only.

Most landfill sources are "sour" gas, the H2S will cause significant corrosion issues with turbofan GG (Gas Generator) rotors. Aeroderiviative turbine power is ideally suited for regular natural gas, not for corrosive gases

 

Landfill gas facilities have a scrubber to pre-treat the gas. I assume that they also remove the CO2 that is present in large quantities in biogas.

 

Lakes such as Mono and Great Salt have miromixis - where a lens of fresh water floats atop the saline, until the whole lake turns over. There are density gradients that create currents. There are fresh water springs that create currents. It is not just inflow, evaporation or suface wind.

 

The scrubber will primarily take care of VOC's that are present in landfill outgas, it's difficult to remove enough H2S to protect a turbofan powerplant.

That is, the level of scrubbing and centrifuging will increase the cost to the point its not worth doing

The residuals still have to be dealt with, which is why a flare stack must be maintained

 

So how do the landfill gas powerplants function then? They must be removing the H2S economically somehow.

 

The landfill sites are using the scrubbers to remove just enough H2S and VOC's to ensure reasonable life from the equipment. The efficiency of the scrubber packed tower also depends on the type of packing used. A typical packed tower scrubber

Air Scrubbers: Packed Bed

An important consideration for any packed tower is that it doesn't magically make the contaminant disappear. Whether H2S or VOC's, it will then end up in the packed tower water cycle.

You then have a choice of discharging the water to the cooling tower, which will put it in the atmosphere, or running the tower water through a RO membrane process. You then have the retentate to consider, how to safely dispose of it

This is a very complex process field, not sure how much you want me to explain it. Please let me know