Increasing the Efficiency of Aeration in Aerobic Wastewater Treatment

Aerobic wastewater treatment uses microorganism to feed on waste in the water and convert them to sludge, carbon dioxide and water. To keep the process going, the wastewater needs to be aerated with oxygen. There are many types of aerators used for this purpose, but all of them involve huge input of energy. Aeration in wastewater treatment is a very energy intensive process. One small wastewater treatment for a PE (Population Equivalent) of 80,000, for example, consume 2,400,000 kWhr. (Malaysian Ringgit 600,000 or USD169,671.26) annually just for aeration. Increasing its efficiency even if only by a small percentage may make a significant difference.

Wouldn't it be great if one can have an aerator that can add oxygen to the wastewater without great "external input of energy"? What is this "Zero Energy Input" Waterwheel Aerator all about? I know this "Zero Energy Input" thing will raise some eyebrows! Essential, what it aims to do is to make the energy intensive water aeration more efficient. What I am refering to is a waterwheel aerator using the EXISTING surplus kinetic energy present in wastewater treatment systems to power the aerator to squeeze more oxygen into the wastewater. Thus there is no need for expensive additional input of energy. In oxidation ditches, excess flow velocity is detrimental to the oxygen transfer rate and need to be slowed down. In fact, it seems baffles are introduced to slow down the velocity:

"Where power input intensity is high, for example when treating strong wastes, the induced velocity in the ditch will also be high and the differential speed between mixed liquor and rotor blades reduced, causing a loss in aeration efficiency. This may be overcome by installing deceleration baffles upstream of the rotor. A steel channel or timber beam submerged in the top layer of the ditch and spanning the ditch width may be used" (M A Pells "Oxidation Ditches in Wastewater Treatment" p209).

So if it is necessary to slow down the velocity, why not use it to power a waterwheel to squeeze more oxygen into the wastewater?

The device (Rotafall) being proposed consists of circular discs fitted with suitable number of paddles. When flowing wastewater pushes against the paddles, the discs rotates. As the discs rotate, wastewater clinging to the surface of the discs are brought up and large surfaces of the wastewater are constantly exposed to the air for the diffusion of oxygen into the water. Tests shows that rotafall can add about 3.3 to 4 kg oxygen per square meter surface area per annum. A plate has 2 surfaces, so per square meter of plate it can add 6.6 to 8 kg oxygen to the water. To further increase the efficiency, the plates can be colored black to absorb solar energy. This will increase the temperature of the bacteria culture sticking on the plate, and will increase in exponential manner the rate at which they uses up the oxygen in the wastewater, and thus a lower dissolved oxygen concentration in the wastewater. A lower concentration will lead to a higher oxygen transfer rate.

The concept is sound, the device put waste surplus kinetic energy to work, it works. Only question is, can one construct the waterwheel aerator cheap enough, or will the cost of energy increase enough to justify the amount of additional oxygen added to the wastewater.

Some wastewater treatment plants use diffusers which produces rising air bubbles to aerate the wastewater. Thus, another version of Rotafall is feasible. This one will use the buoyancy provided by the rising bubbles trapped in the paddles to power the rotation of the waterwheel.

Update 15 June 2007

To date, I have obtained only 6 comments in this post to date, some of which were spam comment and had to be deleted. There were no comment on whether this innovation is workable and viable. Trying to get more feedback. How to do it? Found someone asking a question What is Carbon Dioxide. I saw 2 answers there, one of them which was very good.

So I decided to join BlurtIt and ask a question related to this post. Signing up was easy. I then proceeded to ask a question, but found they have a limit to the number of maximum 100 words, and there is a word count which didn't seem to reflect the actual number of words. Anyway I proceeded to type my question including a hyperlink to this post which has a long URL as shown below:

http://aerator.blogspot.com/2005/10/increasing-efficiency-of-aeration-in.html

I proceeded to type the HTML including pasting the URL in, but couldn't see the end of what I entered into the question box. So what I did was to edit the hyperlink HTML so that it just consist of the above URL minus the <a href=".... I couldn't see or access the end of the question and posted it anyway, but it was actually published with the full URL visible, but not clickable. You can see the question here: Is this a workable solution to increasing aeration efficiency for wastewater treatment?. I wasn't happy that the URL was not clickable.

So I tried to resort to using http://tinyurl.com/ and redoing the question. I really can't remember fully what I did, but I do remember observing that the end of my question still wasn't visible or accessible. I think I went ahead to test it anyway, tried to change the question to "Is this a viable solution to increasing aeration efficiency for wastewater treatment?". The response was "This question has been asked before...." even though I changed the title of the question. Now just in case my inability has anything to do with asking a question more than once, etc., I opened a different browser and signed in again. (This is one advantage of using more than one browsers which I have often recommended to bloggers in my post Why you should be using more than one browsers. I still don't understand why so many surfers are sticking to just one browser Internet Explorer 6 when there is one highly recommended and superior browser What is Firefox and why you should be using it, which offers the very useful tabbed browsing and other advantages.

Anyway, I signed in to BlurtIt again in a new browser and proceeded to ask the question, this time using the short URL that tinyurl.com generated for me. This time, I prepared the message in MS Word with the following question with HTML as shown in the scrollbox below:

Can I get feedback if <a href=http://tinyurl.com/2vpjpc>Increasing aeration efficiency</a> is viable?

I did a word count and came up with the following result:

Words: 11
Characters (no spaces): 91
Characters (with spaces): 101

The last one exceeded 100, so I really don't know if I would succeed in publishing the question. Anyway I proceeded to copy and paste it into the question box, and I think the end of the question still wasn't visible or accessible. I clicked "Ask my question now" and the question actually got published with a clickable link to this post. You can see the question at Feedback on an innovation please.

Let's see if I get a response there or some additional feedback in the comments here. Also, I see a "Help" link at BlurtIt and I will take the trouble to ask them why I am having difficulties in seeing or accessing the end of the message and if anything can be done. Will update this post if I managed to contact them and get a response

Lawn aerator for healthy lawns

Why would any home owner wants a lawn aerator? Often foot traffic can cause the soil to be compacted which is not conducive for the uptake of plant nutrients and life giving oxygen. By aerating your lawn you will make your lawn more porous which can help make the uptake of nutrients and oxygen more efficient.

Membrane filtration halogenated by-product control

A common disinfectant used for water treatment is a 15% solution of Sodium Hypochlorite NaClO (Chlorination). It is made by reacting Sodium Hydroxide with Chlorine

2NaOH + Cl₂ = NaCl + NaClO + H2O

Chlorination of drinking water can oxidize organic contaminants, producing trihalomethanes (also called haloforms), which are carcinogenic.
Source: Wikipedia

One way to solve this problem is to use membrane filtration to filter off the precursors of halogenated products.

Garden aerators and mailboxes

A home is not a bare house. It normally have a garden, rooms, kitchens, bathrooms, plus you would need to have a mailbox for your friendly postman to stuff in your letters in. You wouldn't like the friendly postman to throw your mail on your doorstep would you? If you don't provide a mailbox to receive your letters, that is just what might happen.

A garden need to be maintained. One of the problem that a garden may face is soil compaction which leads to poor aeration of the soil. To overcome that problem, there are garden or lawn aerator. There are 2 main types. One uses spikes to punch holes in the soil. Another pulls out plugs of soil. The second type is called a core aerator. It remove cores of soil to allow air contact.

A home, as mentioned earlier, also needs mailboxes. With the ubiquitous Internet, getting one that suit your home and your budget is easy, as you can verify from the above link.

If your home has a garden, a good choice is to have self-standing Column Mailboxes or you may prefer other types of residential mailboxes which are mostly wall mounted mailboxes.

That would make your home complete, a well aerated garden where earthworm can live in comfort and keep your lawn healthy and a mailbox to receive your important correspondences.

However, a home with a family need sustenance. To sustain a family requires the bread winner to work at a job for a salary to take home, or to run a business. The site mailboxixchange also have a range of Commercial Mailboxes for his office or factory premises.

Economics: Viability of the Zero Energy Input Waterwheel Aerator

This is a reply to someone in a forum which can also be a discussion on the viability of this Zero Energy Input Waterwheel Aerator (click BACK button to get back to this page).

Hi Richard,

Thanks for the interest. The concept is good - use waste surplus energy for something useful, the problem is economics, the low price of electricity. As mentioned on the site, it can put 3.3 - 4kg of oxygen per annum per meter square of surface area. A plate has 2 sides, so per sq. meter of plate can get about 6.6-8kg of oxygen. This from the table for efficiency

Efficiency of Aeration System (click BACK button to get back to this page).

The least efficient uses 1.10 - 1.64kWh per kg oxygen
Cost of electricity depend on which country or location you are in. Some ideas may be obtained from

Basic Electricity Statistics (data for 2005 except where noted)

According to that site, cost to industry=5.13 US cent. That means the device can save max 40 US cent per annum. If we aim for cost recovery in 5 years, the device has to cost less than US2.00 per sq meter plate.

However, note that the cost of energy, especially petroleum and gas, is constantly increasing, and what may not be viable today may be viable in the future when the cost of energy (electricity) is sky high.

Opportunity to promote my innovation and services courtesy of Gumtree

I have published posts about my and my country's close links with Australia, so it is to my pleasure to come across this site Jobs in Adelaide. It is a site where you can post free advertisements. In the above case, it will be for advertisements related to jobs in Adelaide. I have sister, brother-in-law, nephews, nieces, colleague, friends and relatives spread around Australia, but I don't have any to the best of my knowledge, in Adelaide. Neither am l located in Adelaide. However, the consultancy and services job I seek can be done from any part of the world with an Internet connection, so I have no hesitation in posting a free ad at Jobs in Adelaide (or any part of the world) which will at the same time draw attention to the innovation that was instrumental in getting this blog started. This is an opportunity from heaven that need no money, only the time in preparing the ad.

You can see the ad at
http://adelaide.gumtree.com.au/adelaide/13/14683413.html

I did not make that an active link because as time goes by, the ad drops further down from the top of the page and I do not know if eventually the ad will become offline. If that happens, it will become a dead link, and search engines spider do not like dead links. It can affect a site search engine ranking. But Gumtree is very good in that they send an email to you as the ad drops from the top of the page, and to put it at the top, all you need to do is to click on a link. I would suppose if I continue to do that, the ad will continue to be online, but I can't be sure. If you want to see my ad, you will have to copy-paste the ad URL into your browser address bar and press the ENTER key.

Gumtree do not just post the kind of ad I posted. The also have Adelaide classifieds where you can post your ads in categories including Flat/House Share, Flat/House Rent, Stuff for Sale, Cars for Sale, Community, Friends/Dating, Jobs and Business Services.

This, Dating in Adelaide, should interest those who are looking for soul mates. If you are single, available and interested, try that site. If you are married, I hope you keep away. No offence meant, just common decency.

What you need for innovation

This blog is about an innovation on how to increase the aeration efficiency of wastewater treatment as described at Increasing aeration efficiency in wastewater treatment and Zero Energy Input Waterwheel Aerator.

However, before you can come up with innovations like these, you need a good grounding in education and a wide general knowledge plus preferalbly a passion for innovation and independent thinking. A good start is to have some tutoring help like what your can find at Online tutoring which means you can get tutoring in a wide range of subjects at a touch of a button form your computer at home with Internet access. Included in the range of subjects you can get online tutoring are Maths and Algebra which are basic requirements for all field of studies.

Tutoring in particular subjects may not be the only thing you need. You may need help with homework in which case Homework Help will be a good help.

With a good foundation in basic education, you will be much better placed with coming up with innovations which are essential for the continued progress of our civilasation.