MORE OPERATOR FOLLIES

A nice Ohio WWTP put sludge into the waters of the state (well a ditch anyway) when an operator was told to transfer sludge from one tank to another, and then failed to turn the pump off and overflowed the tank.  Andy Barienbrock is trying to help you out with his minimum staffing, but full automation and unattended operations is looking good

PROCESS CONTROL WITH A FLOWMETER PART 4

In this last part we will look at how to account for sludge blankets that or 2 feet deep and more.

In this example wwe will use the old Lynn Marshall average between MLSS and RAS

But Jim! We don't have any MLSS or RAS data!

Fear not, nimrod, I'll show you how

Lets use the 70' diameter clarifier from above

The blanket depth is 2 ft

The blanket volume is 35 x 35 x 3.14 x 2 x 7.48 = 57,500 gallons

to get the MLSS equivalent volume we take the average of the RAS solids and the MLSS solids

From the above lessons, the RAS equivalent is 3 and the MLSS equivalent is 1.  So

MLSS equivalent = 3+1/2 or 4/2=2

MLSS equiivalent gallons = 57,500 x 2 = 115,000 gallons

Total MLSS = 1,000,000 + 115,000 = 1, 115,000

for an 8 day MCRT  1,115,000/8 139,375 gallons as MLSS or 46,500 gallons as RAS

Pretty neat, huh?

A NEW MUSICAL INTERLUDE

I have been reading one of my favorite blogs,  http://www.fredoneverything.net/. , and thinking about moving to Mexico as No one is hiring me.  And with that in mind, some music from Steve Miller.  I coldn't find a good version by Steve Miller, so her is one from Les Dudek

53 Studebaker going for broke............

PROCESS CONTROL WITH A FLOWMETER, PART 3

Some of you are going to whine and say, "but Jim, you forgot about the clarifier inventory!"  I haven't forgotten.  I am just bringing you along one step at a time, and lots of you never consider the clarifier inventory, or use the OEPA calcualation, which is WRONG ( I hope Andy Barienbrock doesn't read this, or he'll never renew my license: I'm already in trouble for standing up to Dear Leader).  I will show you 2 ways to calculate the clarifier inventory as MLSS gallons.

The first way is to assume that the clarifier inventory is pounds is 25-35% of the aeration tank inventory and then add it to the aeration gallons, like this

Total inventory = aeration tank volume X 1.25 = 1, 250,000 from our earlier examples

For an 8 day MCRT, then 1,250,000 gallons/8 =156,250 gallons of mixed liquor to waste, or for mixed liquor as determined in part 2, 156,250/3 = 52,100 gallons of RAS.

Alternatively, you can measure the blanket volume and calculate an MLSS equivalent inventory, like so

Inf. Flow = 2 MGD
RAS Flow = 1 MGD
Aeration Tank Volume = 1MG
Clarifier Diameter = 70'
Blanket Volume = 1'

If the blanket is 1 ft. deep, I would assume that all the blanket is the same concentration as the RAS.  If it is deeper, you should make a different assumption.  Thats for part 4.

the volume of one foot of blanket is pie are squared x 1 ft. or
35' x 35' x 3.14 x 1ft x 7.48gal/cf = 28,800 gallons
The MLSS equivalent is 3 x 28,800 = 86,300 gallons

Therefore, total MLSS inventory as gallons of MLSS are 1, 086,300

For an 8 day MCRT of MLSS to waste it's, 1,086,300/8 = 135,787 gallons
as RAS it's 135,787/3 = 45,262 gallons

That wasn't so hard, was it?

NOTE: when you waste RAS you should do it with a timer on the pumps so you can waste out during all parts of the day.  RAS concnetration changes during the day and to have an accurate portion, you need to remove some several times during the day,

PROCESS CONTROL WITH A FLOWMETER, PART TWO

In part 1, I showed you how to do process control with and aeration, a flowmeter and wasting mixed liquor.  Now you are going to complain about wasting mixed liquor.  So now I will show yoyu how to do it with RAS

Lets review the conditions

Flow = 2 MGD
RAS Flow + 1 MGD
Aeration tank volume = 1 MGD

The RAS will be more concentrated than the MLSS, so we have to find the concentration factor.

Isn't that east?  No sampling or analysis and no nagging from me to do your sampling right

For the next lesson wil will add the clarifier mixed liquor inventory and not use the lab.

The concentration factor is:  Influent Flow+RAS Flow/RAS Flow
Or 2 MGD + 1 MGD/1 MGD  = 3/1 = 3

By mass balance the RAS is 3 times as concnetrated as the MLSS.
So, the RAS flow needed to maintain an 8 day MCRT is 1 MG/8/3 or 125,000/3 = 41,700 gallons

If you have problems with this call me at 419-367-2749

MERRY CHRISTMAS

Here is a nice little rendition of this song

Merry Christmas

PROCESS CONTROL WITH JUST A FLOWMETER, PART ONE

You all know that I think your samplings ande testngs are inadequate to get an accurate quantification of your mixed liquor inventory, and how much you waste.  I'm sure you are all irritated at my daring to suggest that you do extra work.  So, I put the little gerbil in my head to work and came up with an easier way for you to do process control.  Actually, I thought this up years ago but didn't publish it.  In the interim, Alex Exter, the mad Russian, and others have published papers on it.  Still, I thought it up myself with no help, like Newton and Leibniz with calculus. Here is a simple example.  More complex examples will follow after you digest this one

Lets take aplant laid out like so

Flow 2 MGD
RAS  Flow 1 MGD
Aeration tank volume  1 MG
Clarifier dimensions  70' diameter x 12' swd
Desired MCRT  8 days
Wasting Mixed liquor to primary tank

The aeration tank has one million gallons



like this





If you are wasting mixed liquor, to maintain an 8 day MCRT, you waste 1/8th of 1 million gallons or 125,000 gallons

See, that's easy, no pesky sampling and analysis.  Your flow meter is more accurate than your sampling and analysis.

Next time we will figure out wastime with RAS

ANOTHER MUSICAL INTERLUDE

I dont know how many of you remember the Beach Boys song "Heroes and Villains"  It was produced in the studio with lots of separate tracks melded together.  Here is a group, the Fendertones, who do it perfectly, live, with no overdubs.  Amazing

COMMENTS

To all my loyal fans:  Feel free to leave a comment, even to say hi

COMMENTS

Visitiors, don't be shy about leaving a comment, even just to say HI!

THE COST OF HAULING WATER, PART 2

Last time I looked at the cost of hauling liquid sludge.  This time I will look at hauling cake.

The table below shows the cost of hauling cake at $25 and $20 per wet ton.

TABLE 1
THE COST OF HAULING CAKE

CAKE SOLIDS	TONS WATER/TON SOLIDS	COST/DRY TON @ $25/WET TON	COST/DRY TON@ $20/WET TON
15%	5.6	$166	$133
20%	4	$125	$100
25%	3	$100	$80
30%	2.3	$83	$67
35%	1.8	$71	$57

You can see from this table and then comparing cake vs. liquid hauling costs that:

• cake hauling is less expensive than liquid hauling until you get the liquid solids up to 6% or more
• if liquid hauling is more expensive than 3 cents/gallon, cake hauling will be cheaper at any concentration
• You save a lot of money getting the cake colilds from 15% or 20%, but not so much from 30/5 to 35%

So, what keeps you from switching over to cake solids immediately?  The cost of the dewatering equipment.   I wont't go into the actual costs herede but you will need:

• The dewatering machine
• A polymer feed system
• A building for the dewaterng maching
• A conveyor
• A cake storage pad, preferably a COVERED storage pad
• A front end loader if you don't already have one to load the cake
• Utilities to the building.
• A mechanism to get the cake to the storage pad, either a conveyor (preferred) or a dump truck ( not preferred)
• If you are DIY on sludge hauling, you will need 30 cubic yard dump trailer(s) or lots of dump trucks.

You will have to do your own arithmetic.  Cake hauling prices range from less than $15/wet ton to over $25/wet ton depending upon location and competition

What kind of dewatering device?  Thats a whole other lecture.  Centrifuges make the dryest cake but may not be the most cost effective for you.  Rotary presses do well on some sludges and have some advantages on water use, odor and noise. Belt presses are less expensive than centrifuges, but the cake is usually wetter.  For the smallest operations, simple geotubes work best.  Hire me and I'l help you figure it out.

THE COST OF HAULING WATER

If you haul sludge, liquid or cake, increasing sludge solids before hauling can save you a lot of money.  For example, one ton of sludge at 2% solids is 2000 Lbs of solids and 98,000 Lbs of WATER.  If you thicken it to 4%, now you still have 2,000 Lbs of solids, but only 48,000 pounds of water.  If you are paying by the gallon, you just cut your bill 50%.

I'll show the effect of thickening on your hauling bill here.  Assume that hauling cost $0.03/gallon

COST OF HAULING ONE DRY TON OF SLUDGE VS SLUDGE CONCENTRATION

Total Solids	Pounds Water	Gallons	Cost per Dry Ton
2%	98,000	11,990	$359
4%	48,000	5,995	$180
6%	31,333	3,996	$120
8%	23,000	2,997	$90

Hauling at 2% is pricey, isn't it?  If you land applied 200 dry tons at 6% instead of 2% you would save $48,000 in hauling cost.

How can you improve your solid concentration?  You can supernate caefully, and often to improve solids concentration.  You can have a dedicated storage tank for concentrating solids.  You can buy a thickener, and thicken the solids prior to land application.  I always wondered why consultants never recommeded small dedicated storage tanks and then a gravity belt thickener to jack the solids up to 8% solids just prior to hauling.  It make a lot of sense. 

MUSICAL INTERLUDE

Ever have songs that just go through your head?  Here is one of mine.  Here it's sung by a group called Harmony Grass. You can also find versions by the Four Freshmen, Spanky & Our Gang, and a Filipino group called the Bloomfields.  Note the dated references to Northwest Orient, DeGaulle and the Coconut Grove, and that you could get jailed in France for making fun of Degaulle.  He did have an extrordinarly large honker.

OPERATOR FOLLIES

A nice plant in  Ohio got their DC motor sludge feed pump motors wet after a storm.  The pump stateion had a poser outage and the sump pumps did not work, allowing water for the extensive basement to flow to the lowest point in the building.  The storm was on Friday.  The wet pumps were discovered on Monday morning.  The plant is staffed 24/7 by operators, including weekends.  I do not know the work schedule, but I assume that the operator makes rounds twice an 8-hour shift.  How could such a thing happen? At least 3 different men have to not go to the basement over the course of 7 shifts.

Automation sounds like a good idea..

PERIPHERAL FEED VS. CENTER FEED CLARIFIERS

You may know that I have been a big fan of peripheral feed clarifiers for many years.  Why?  Can you say 10 mg/L TSS at an SOR of 2000 gpd/sf?  Thats double the 10 states standards flow limits.

How do peripheral feed and center feed differ?   Let’s look at a cutaway of a center feed clarifier.  

 (Image from Westech)

At peak flows under 10 states standards, the MLSS and RAS flows upward in the column at abougt 3 fr/sec (fps).   It exits the ports at about the same velocity.  The velocity in the flocculation chamber is about 0.19 fps, and the detention time is about 1.1 minutes.

When the flow exits the center column, it hits the flocculation basin walls and has nowhere to go but DOWN, creating a current called the waterfall effect.   The waterfall can disrupt the sludge blanket.  The current then flows along the bottom till it gets close to the weirs, where it rises,  This current will pull solids along with it and degrade clarifier performance.

Now lets look at a peripheral feed clarifier 

(Figure taken from SIEMENS, thanks)

Mixed lliquor enters the tank through an outer raceway (1), which circles the tank.  Flow drops through the floor through a tube .  The velocity through this tube at peak 10 state standards flow is 0.50 fps.  The area just below the raceways has a target baffle (8) and a skirt baffle (9).  The target baffle breaks up the current from the drop pipe.  The skirt baffle provides a large flocculation zone that is an analogue to the center feed flocculation basin.  The sludge velocity behind the skirt baffle is 0.018 fps, or 1/10 that of the center feed tank. The detention time is 83 minutes as opposed to 1.1 minute

After leaving the flocculation zone, the current pushes the sludge to the center of the tank, the clarified water loops back and leave the tank by the effluent raceway adjacent the influent raceway

There are 3 keys as to why peripheral feed tanks are better:

1. They provide less turbulent conditions.  Good gravity settling means getting rid of turbulence, and allowing the flow to form.  Violent conditions shear the floc and slow down settling
2. The long flow path essentially doubles the water’s travel path from inlet to outlet, reducing short circuiting and providing more settling time.
3. The flow path takes the sludge blanket away from the effluent launder and towards the center of the tank.  This is the reason why these tanks perform s well at high flows; the blanket is being pushed AWAY from the launder, not TOWARDS it.

OTHER GOOD THINGS ABOUT PFPO CLARIFIERS

Head loss and flow splitting

PFPO clarifiers have a significant advantage in headloss due to the lack of the center feed pipe.  The reduction in head loss has advantages in elevation. flow capacity and gives youhead to burn for good flow splitting.

Next, flow splitting.  With the peripheral feed, mixed liquor can flow from the aeration tank to the clarifier through an open channel, wheich can be an advantage.  If you are using a diamond shaped flow splitter for 4 tanks, the splitter can be made simpler and closer to the tanks.  Another advantage is with tanks in a line.  I remember she Ohio EPA "SWAT" team using their fancy fluorometer (which my employers would never buy me) to demonstrate problems with flow spitting in recgtagular tanks in a line.  They were able to improve flow splitting by using  (I swear to God) pieces of shingles to add headloss to the clarifie inlets to improve flow splitting,  With a PFPO clarifier, you can put in a weir or a flume and measure the flow, and add an up-to-close weir gates to adjust flow to each tank.  WARNING! Do not allow too many people the ability to adjust the flow to individual clarifiers, or write a computer program to do it, because overadjustment leads to instability and poor performance.  The ability to adjust the gates can lead to "fingeritis", a sin of which the Author (that's me) has been guilty in the past.  It's best to adjust the gates so the flow splits are pretty good most of the time rather than seek perfection.

OTHER ADVANTAGES

Other advantages of the PFPO clarifier are reduced construction costs, and the sheer elegance of the design.  Whats's wrong with elegance?

I have never figured out why more engineers don’t build these tanks.  The Chinese have standardized on them.  After all, one billion chinese can't be wrong.

I want to thank ED ROGOZINSKI for the data on center feed clarifiers.  May god bless you and your sons.  and now, for Ed  a little musical interlude.

HEAVEN ON EARTH

This is one of the most beautiful songs, especially stirpped of the instrumental music.  You can hear that the vocals are double and triple tracked to strengthen the voices.  This song reminds me of my first girlfriend.  We worked at the cable spool factory in Brookville one summer.  She was a nice girl and I wish I'd held onto her.  She teaches math at a community college now.

Do you hear the "run run weooo" as backing vocals?

SAMPLING

I have written some articles on sampling, most notably Sampling, Analysis and Quantum Mechanics.   I will boil down what I have written before into something easier to read.

First:  very few of you take enough samples or run enough analyses, at least in Ohio.  In Michigan, the State Dept of Environmental Quality makes the plants take enough data to do proper analyses.  Remember, IF YOU DON'T MEASURE IT YOU CAN'T CONTROL IT!  Here are a couple of oddball examples:  An SBR plant doing biological Phosphorus removal had aerobic digesters.  When they supernated the digesters, they blew their Phosphorus limit for the day.  Why?  Because the spernatant had 70 ppm of Phosphorus, and the flow was about 40% of the average daily flow.  Luckily,  they were in Michigan and had to report that on their daily monitoring report.  A second example:  A superintendent supernates the anaerobic sludge storage tanks.  The supernatnant ammonia is about 600 ppm but she does not know that.  I was there that day and asked her to take some samples.  The primary effluent ammonia was 60 ppm, and the activated sludge effluent was 30 ppm.  We were able to divert effluent to some empty sotrage lagoons and recycle it through the plant, avoiding an exceedance.  For my help, I got taken off the project.  Never expect gratitude when you are a consultant.

I have also worked at Class IV plants that did not have enough data to properly calculate volatile solids reductions.

Next, you should all be taking composite samples for your MLSS, RAS and WAS sampling.  Why? Because samples are variable in time and in space.  If you take 10 MLSS samples, one adfter another, you will get a variatioin of about 5% from the average. As to variation over time, as the flows change during the day, some of the MLSS gets transferred from the aeration tank to the clarifier and then later, back.  If you have the operator run out first thing in the morning and take a MLSS sample, then calculate your wasting, and start your WAS pump after noon, you will not waste the right mass; I guarantee it.  It is better to get a 24 hour composite sample and run it the next day to determine  what your MCRT was that day, and base your wasting on history and trends, than to fall into the trap of todays data.

Plotting and trending - No I don't mean plotting your boss's downfall and trending your pay.  I mean your data.  You all have Microsoft Excel spreadsheets, so you can store, plot, graph and trend all you data.  So get to it.

I'll give you another lecture soon

OPERATOR FOLLIES

I know I'm going to be flayed alive for this series,  but I'm tired of hearing about how great operators are and how they save the world when I continually see things like......what I will write about.  And it's my blog.

The first two follies are actually laborer follies.  Several years back I was working at a plant where sludge cake was transported around on conveyor belts.  As this is not a perfect world, sometimes the sludge fell on the floor and needed cleaned up.  Instead of sweeping the sludge into a big dustpan or a shovel and putting it on the conveyor belt or into a trash can on a dolly, or into a big plastic trash sack, the laborers would use shovels and chop or the sludge into very fine particles, so it could be hosed down the drain.  I never figured this one out.  Putting it back on the conveyor seemed to be less effort.

At this same plant it was common to see the laborers in various states of rest in the electical control rooms.  Why?  The motor control centers had variable frequency drives, which in those days needed cooling to avoid drive failure.  Therefore, the MCCs were air conditioned and were very comfortable in the hot and humid summers of XXXXX (almost let it slip).  I never ratted, and it did make it easy to find a laborer when I needed one.  They were agreeable to helping me because I never told management about their hiding place.

What's the best fuck-off spot at your plant?  Write to this blog and post it.

Donuts

DONUTS

Municipal meetings cannot run without donuts. This includes wastewater meetings, and it’s the consultant’s duty to get them (some of you out there will piously and smarmily say that I’m a meanie, but its true). That’s ok I LOVE DONUTS! I can remember one meeting in Defiance years ago, where Jim Donnell and Jason Tansey were supposed to bring the donuts, but they were late and only brought 2 dozen anyway. As soon as I got there, Leon Smith, Pat Tebbe and the lovely Elizabeth Wick said, “Where’s the donuts? Where’s the donuts? We’re hungry!” They looked like little robins waiting to be fed. 2 minutes later Gino Silvestri, the superintendent, got on the intercom and demanded that I go get donuts. I was less than 20 feet from him and he gets on the intercom. He demanded that I go to Kroger’s and get donuts for everyone. I told him I’d be dammed if I was going to put my hands on 8 dozen donuts for everyone. I asked Rory Prigge and Frank D’Ambrosia, who worked there then, where the donut shop was. I got blank looks. I got in my car and found the donut shop. I cleaned them out, left the woman a nice tip and headed back. As I was entering the office, Brad Borer from Tiffin was coming out of the building and said “Donuts! Thanks, Jim” and took a box of half a dozen off the top. Brad always was a great eater. I brought the rest of the donuts in and put them on the table, took one or two for me and got some coffee, gave a hard look at Frank and Rory for not telling me where to donut shop was, and listen to Gino complain because I didn’t go to Krogers. Why did I get all the donuts I could? It’s a sin to not have enough donuts and then some left over for the men when you leave. So there. Hah!

Some of the best donuts in the world are made at Bakery Unlimited, just a few blocks from my house. If you want death by chocolate sugar and fried grease, get the chocolate covered, Bavarian crème filled fritters. All your daily calories in one goopy mess. Do you have a favorite place?

WHY ATAD IS BETTER THAN AEROBIC DIGESTION

WHY ATADS ARE BETTER THAN AEROBIC DIGESTION

I have been accused of being excessively enthusiastic about ATAD. I have designed 2 facilities, Three Rivers, Michigan and Bowling Green, Ohio. The clients like them very much. I will distill down and demonstrate the reasons whey you should have an ATAD and try not to be too boring.

First, what is an ATAD (If I’m not being too pedantic)

Autothermal, meaning it generates its own heat

Thermophilic, meaning the reactor temperature is above 110 F, actually its about 150 F

Aerobic, meaning that during some of its operating cycle. It has a positive oxidation-reduction potential (ORP) and the end produce always does.

Digestion

ATAD is a two stage process. The first stage is a thermophilic stage, of about10-14 days. Autoheating conditions are produced by using a volumetrically efficient jet aeration system with a covered and insulated tank. Solids are fed daily and discharged daily.

The second stage, call a storage, nitrificatioin/denitrification reactor (SNDR) is a mesophilic stage. The digested biosolids have been pasteurized and have been stabilized, but it has a high polymer dose for dewatering. The high polymer dose is caused by biopolymers, which can be ndirectly measured as soluble COD (SCOD), and by monovalent ions (+1). The solids are cooled and aerated for 6-10 days to reduce the ammonia and SCOD, and produce an additional 10% TS reduction. Aeration is controlled to produce a nitrification/denitrification cycle and is controlled by pH or ORP. Solids are discharged daily and discharged daily or intermittently.

Digested ATAD biosolids can be stored as a liquid or dewatered. I suppose they could be dewatered on a sand drying bed as well. Liquid biosolids can be decanted in storage, but it takes several months to develop a supernating biota.

I could go on to a long article here, but I will summarize the ATAD advantages in this table.

PARAMETER	ATAD	AEROBIC DIGESTER
SRT	20 (with SNDR)	45
AERATION POWER	90 HP/DRY TON SOLIDS/DAY	130 HP/DRY TON SOLIDS/DAY
VS REDUCTION	55-75%	25-35%
TS REDUCTION	45-65%	20-30%
DEWATERED CAKE SOLIDS	BELT PRESS 22-24% CENTRIFUGE 30-40%	BELT PRESS 15-20% CENTRIFUGE 22-25%
EXCEPTIONAL QUALITY BIOSOLID?	YES	NO

Every installation, I believe, has seen a big reduction in biosolids beneficial reuse costs. Some success stories of which I know are

Bowling Green Ohio – Went from using 5 operators 65 days a year to haul bioslids to running a centrifuge and giving it away to a topsoil blender. Savings? About $200,000/yr.

Delphos OH - Went from paying $0.09/gallon to Mike’s Sanitation for taking their non class B sludge to giving it all away.

Marshall MN – Reduced liquid volume hauled by 65%

I will add some more later.

An ATAD makes sense at any installation with a capacity of 1 dry ton per day

VECHNAYA PAMYAT ANDREW

It has occurred to me that you need some background before reading this.

Andrew is my son.  He just died.  He was poisoned by his mother when he was 5, and hung on in good humor but much physical pain and suffering until he was 23.

Vechnaya Pamyat means memory eternal in Church Slavonic, the liturgical language of slavic Orthodox churches (Russian, Bulgarian, Macedonian, Serbian, etc).  You can find it on youtube.  No one does melancholy like the slavs.

Koliva is a dish made of boiled wheat, ground nuts, sugar and cinnamon and is offered at memorials and funerals.   It is slightly sweet and signifies rebirth.



LIKE WHEAT FOR KOLIVA

Jim Scisson

His son is dead. Having no wife he must make the koliva himself. He goes to the middle eastern market, full of scowling Moslems who don’t like it that infidels invade their market. He buys 2 cups of #4 wheat, scooping it out of the bulk bin. While he is there he buys a lamb schwarma and a small tamarind soda. The food is amazingly good. He wonders why the Orthodox Christians can’t run a market like that. The Greeks used to run one near his home, but they sold out to the Muslims. He takes the food home and puts it on the table. Later that day he lays down and cries for his lost son. His son left home 5 years ago and come home only occasionally. He was missed every day, no matter what the son or others thought.

The next day is the visitation. He goes early so he can talk to his son in private without the Jehovah’s Witness shrew who lured his son away being there to afflict him It was odd to see his son so tall and still, without his body being rent by spasms. He cries silently as he talks to his son about how sorry his is that things went the way they did, and that he was unable to fix him by the force of his will alone. He sorrows that his son never got to do all the other things boys get to do; play ball, have dates, drive a car and get too much to drink and get in trouble.

Other people show up and he greets them, being careful to be extra nice and courteous to every one, as the Jehovah’s Witness shrew is looking for any excuse to throw him out of his own sons wake. The aunts from Texas show up and talk to his daughter who is there. They are pleased to have a new relative, as 2 of them have never seen Sarah and the other not since 1998. He greets more of his friends and also his daughter’s friends, being careful to be friendly with everyone. He is surprised that a former friend showed up, a man could have hired him, but didn’t. He made a photo memorial of his son with pictures from his whole life. Many were surprised to see how he looked before his mother poisoned him., when he could run and talk, and throw baseballs and play with teenage mutant ninja turtle swords. He takes the aunts out to a late lunch at a Mexican restaurant nearby. The aunts pronounced it passable. Later on he goes home and starts writing thank you notes to the people who sent cards and who he saw at the viewing and knew personally. He goes back to the funeral home and sees some more friends, including one who came 150 miles to see his son. He then goes to the store to get some food for the mercy meal after the religious service on Sunday, rice and chickens and beef and green peppers for his famous crock pot.

On Saturday is the funeral. Even though its by those non-Christian Jehovah’s Witness hooper-goopers, the service was acceptable. He got to be first in the car line as he was the dad. They took his son to the cemetery, said a few words, and left him there. No burial yet. He stays behind to sing Vechnaya Pamyat . Some things just have to be done.

After the funeral, another trip to the store, and then later, making the koliva: Boil the wheat for an hour, drain it, and pour it on the tablecloth and cover it with the rest of the tablecloth. Everything else will be done tomorrow.

The aunts decide to take the daughter out and get to know here. Its lonely that night.

Sunday is church and people are very nice. The Panikheda service is in the evening.

The aunts come over and help get the food ready, cook the rice, etc. He finished the Koliva: grind the walnuts, scrape up the wheat, which he does not think is dry enough but oh well, mix the nuts and wheat together, add some breadcrumbs and sugar, and mold it into place. After that, he covers it with powdered sugar and makes a cross with cinnamon using a stencil his godmother gave him.

At last all the food is ready. It goes out to the cars and to the church hall. The Koliva goes to the church. Margaret made some Koliva too, fearing that he would mess it up. Hers was better, but she has lots of practice, decades of it.

There are about 60 people in church. He sits in the front row, alone, as his daughter will not sit with him. Tony the chanter came back from upnorth to chant for the service. He was pretty grizzly, as he hadn’t shaved for a few days. Tony always makes it sound like the 12^th century and the filthy Turks have yet to overrun Constantinople. The service is very nice, and it ends with the choir singing Vechnaya Pamyat. The father cries silently at the loss of his only son. Why son? Why did you have to die? I told God a thousand times or more that I would die for you so you could live a healthy life. But god didn’t listen.

The food after was very good, rotisserie chicken, the crockpot dish, rice and more, plus Stanley’s famous rice pudding and the Koliva. Slavs are big on dessert and are good eaters too. He and Tony eat at the men’s table while his daughter and the aunts sit at their own table. The rest of the women sit at their tables. He had always hoped that after he got the children back and became Orthodox, he could disappear into that, but it was not to be.

After it was over, the food goes back into the car and back home into the refrigerator.

He sits alone at home and cries. Why Son? Why? Why? You were my only son and I wanted so much for you, and you ended up twisted and wracked with spasms and no foot ball and no driving except for the golf cart that one time, no girlfriends, none of the things boys get to do, just endless hours of anime. I loved you so much, and now you are gone.

Vechnaya Pamyat, beloved son.

IDLE MUSINGS

AEROBIC DIGESTION PART TROIS

Now for some process control.  Wake up everybody, and turn off your cell phones.

You can improve your digestion and save a llot of energy by following a few simple rules

Most digesters nitrify.  Nitrification makes acid and reduces the pH.  pH depression can get as low as 3.5, which then pickles all the organisms and you have a pretty dead digester except for some yeasts, and your girlfriend will tell you about those nasty yeast infections.

pH can be restored by turning off the air and allowing it to denitrify.  Denitrification is slower than nitrification, so, for best results, you should turn the air off for twice the time you aerate it, and I'll show you as soon as I can get this pesky blogger to allow me to paste a drawing.  In real world terms, this means you can turn the blowers off when you leave for the day at the end of the day shift, and turn them back in the morning.  You will then track your pH to see if that is effective.  When it's hot out you will have to run the blowers longer.  Thats why you have timers on your blowers.  Pay attention to whats happening and make changes as needed, instead of doing nothng and then blaming the engineer.  You will end up with a sludge tha dewaters/decants better and save energy.

Other indicators

pH is slow to change.  It may be that you need to look at ather values to control your operation.  You all are out of the dark ages and will have these tests available to you, so quit howling at the darkness and get to work.

Ammonia

Nitrification destroys ammonia, meaning you have aerobic conditions.  Septic conditions create ammonia, as it evolves out of protein destruction.  Since you are most likely testing your effluent, you can test your digester too. You;ll have to figure out for yourself what ammonia values are too high, but 125 mg/L is a place to start.

Alkalnity

Alkalinity is a measure of the sludge buffering capacity.  Depending upon conditions, alkalinity will range from 0 (too low)  to 700 or more (too high).  Adjust your air accordingly.

Total Solids

If you are thickening your sludge, especially with a mechanical thickener, you need to watch your solids and make sure it does not get too thick, unless you are going to unerated  storage.


It can be that easy if you are not so stubborn as to do it different just because.

IDLE MUSINGS

My son Andrew was a big Pokemon fan when he was younger.  Besides collecting the cards, we played the games and bought the Pokemon movies.  We even bought a soundtrack CD.  One of the songs on the sondtrack was Al Yankovic's "Polkamon"  When I would play that both Andrew and Sarah would CRY.

AEROBIC DIGESTION, PART DEUX

This section was going to be on operations but I didn't cover enough on blowers and diffusers, so now I will.

Blowers

Every book you read says you must use PD blowers for aerobic digesters, and cannot use centrifugal blowers.  This is a lie. (I'd use stronger words, but someone would be offended).  Centrifugal blowers can be used, and can supply multiple tanks.  All you, the operator, has to do is use the air flow control valve on the drop header to each tank, and pinch back the tank with the lowest level so all the air does not flow into that tank.  Stop watching the TV and do a little work.  Why use centrifugals?  They are more efficient than PD blowers and much quieter.  The PD blower manufacturers are now offering PD blowers with VFD for speed control and nice enclosures to get the noise level down to 70 dB or even less.  Aerzen, for one has a nice package for that, and easy access for maintenance as well.



In addition to air flow control valves, each tank drop should have a flow meter.  Why?  BECAUSE IF YOU CANT MEASURE IT YOU CAN'T CONTROL IT!  I know, I'm a slave driver, spoiling your day making you write down all these data  boo hoo.

Diffusers

There are numersou diffusers, both fine bubble and coarse bubble that can be used.  I think that some are better than others.  Mooers flex cap diffusers work well in digesters and are better at resisting fouling that some.



Fine bubble diffusers can be used for aerating digesters, and require less air than coarse bubble diffusers.  They are more prone to fouling, but EDI promotes fine bubble diffusers for aerobic digesters.



As I said earlier, the kind of diffuser you use limits the reactor total solids.  With fine bubble diffusers, the tanks solids should be less than 3% TS.  For coarse bubble duffusers, less thatn 4% TS.  If you want to see proof, write to me and I'll bore you with all the calculations.

ORP meters.

To know the conditions inside the tank, an ORP (oxidation-reduction potential) meter is better than a DO meter.  ORP tells you how and how to cycle the air flow to good effect in part trois.

WHAT YOU NEED TO KNOW ABOUT AEROBIC DIGESTION ,PART ONE

People think I’m an aerobic digestion expert, and I was an author on the latests EPA solids handling manual, so I’ll give you a boiled down (not sleep inducing) version of what I think you should do.

What is aerobic digestion?

Aerobic digestion is dieting. Waste activated sludge is put in a reactor and aerated. The organisms run out of food and die, and the cells lyse, providing food for some of the remaining organisms. There is nitrification going on too, and, hopefully, denitrification as well. The chemical formulas for all this are:

C₅H₇O₂N + 5O₂ => 4CO₂ + H₂O + NH₄HCO₃

Destruction of biomass in aerobic digestion

NH₄⁺ + 2O₂ => NO₃^- + 2H⁺ + H₂O

Nitrification of released ammonia-nitrogen

C₅H₇O₂N +7O₂ => 5CO₂ + 3H₂O + HNO₃

Complete nitrification

2 C₅H₇O₂N + 12O₂ => 10CO₂ + 5H₂O + NH₄⁺ + NO₃^-

With partial nitrification

C₅H₇O₂N + 4NO₃^- + H₂O => NH₄⁺ + 5HCO₃^- + 2N₂

Denitrification using nitrate nitrogen as electron acceptor

A PRACTICAL EXAMPLE OF DIETING

C₅H₇O₂N +5.75O₂ => 5CO₂ + 0.5N₂ +3.5H₂O

With complete nitrification and denitrification

Biomass gets turned into carbon dioxide and water. Ammonia gets turned into nitrate and hydrogen ion, Nitrate gets turned in to nitrogen and oxygen and half of the hydrogen ions are taken up into hydroxide.

How to design a digester

A digester should not be a wide spot in the pipe where you play around with it when you feel like it. An aerobic digester is a reactor, and should be treated as such.

How big should it be?

In the Midwest, 45 days SRT is enough, based on the chart below .The 45 days is for the reactor. Liquid storage is separate.

How may stages should it have?

I think 3. 2 Stages gets you a 25% reduction in SRT needed, and 3 stages lets you take 1 tank out of service for cleaning or whatever without adversely effecting your operation.

Should it have covers?

In places where it gets cold, one tank or more should have a cover for heat retention. NOTE WELL: In the summertime a covered tank will autoheat, stink and foam up (not good). You need to be able to take part of the cover off, or have lots of hatches, or use the covered tank as the 3^rd stage or liquid storage. Of course, you operators can do what you want and then blame the consultants when it doesn’t work.

What kind of diffusers should I use?

You can use either fine bubble or coarse bubble diffusers. Both have different qualities and limitations. See the section below on how thick your sludge should be

Should I thicken the sludge

There are several methods for thickening the sludge, including

• Supernating. If possible you should get an SBR decanter for supernating instead of a telescoping valve. It will save a lot of time and allow a cleaner supernatant to be decanted. Another option is to tie a submersible pump to an inner tube and float it in the digester on a long hose and electrical cord. I designed a system like that in Bowling Green. Supernating usually thickens the sludge up to 2.5%. Your results may vary
• Belt thickeners and Drum thickeners. Mechanical thickeners can thicken the sludge up to 10% or more if you want to use high doses of polymer. Not a good idea. You aeration system will not handle more than 3 or 4 % solids (more on this later) and you will end up with a putrid, quivering mess. Limit your thickening to about 5% TS out of the machine.
• Membrane thickeners (MBT). This is the most elegant way to thiken aerobic digester solids, especially if you do it as a recuperative thickener. What is a recuperative thickener? Its one where you pump think sludge from your digester to the thickener, usually at about 200 gpm. The membrane underflow pumps are set to pull out a small amount of permeate – as little as 10-15 gpm, but maybe as much as 25-50 gpm depending upon the capacity. This thickens the sludge up a little, and it falls by gravity back into a digester. You run the MBT until youget it as thick as you want it usually 3 to 3.5% TS. What’s so elegant about this? You don’t have to pay much attention to it. You turn the system on and it can run for days before it needs attention. In addition, you don’t have to worry about phosphorus recycle as you do from supernating. When you supernate a bio-P sludge, you can get phosphorus concentrations as high as 70 mg/L, which will ruin your day when it recycles to the aeration tank. The permeate can be discharged to the plant effluent

An example is shown below

Sludge Thickeness

Sludge thickness effects oxygen transfer efficiency. Oxygen transfer is less efficient as the sludge gets thicker. The point where process air exceeds mixing air is about 3% TS for fine bubble diffusers, and about 4% TS for coarse bubble diffusers. I’ll show you all the boring calculations another time because this article is getting long. Trust me.

Tank height

Some people advocate building really tall tanks (22’) for improved oxygen transfer efficiency, This is true, but the increased pressure on the diffuser at the tank bottom requires extra energy. With cheap energy, it’s a wash. With expensive energy, it costs you more to have a deep tank than a conventional tank.

Liquid storage

LIQUID STORAGE DOES NOT NEED TO BE AERATED! One you have stabilized it, you do not need to keep aerating it, If you do, you just make pH problems for yourself by nitrification, and if you get it really thick, you blow the stink up in the air.

To recap, the digester should be

• A reactor, not just a wide spot in the tank
• You should have 45 days SRT in 3 switchable stages
• Storage is separate from a reactor
• Don’t make the sludge too thick
• MBTs are great
• Liquid storage does not need to be aerated.

The next posting will talk about operation and troubleshooting.

WHY IS MY BLOG CALLED WHAT IT IS?

You can thank Mark Buchenic for that.  We were making a presentation to a client, and we used that photo at the top of my blog.  Mark insterted a cartoon balloon that said "Let's talk about poo".  So I am using it.

INTRODUCTION

I am a wastewater treatment operator, wastewater plant designer, process "expert" textbook author, and writer of articles on wastewater treatment.  I have 33 years experience and have decided to put my thoughts down here for others to read, if you want to.

I have lived and/or worked in Caledonia OH, Lewisburg OH, Ketteriing OH, Bloomington IN , San Antonio TX, Houston TX, Sarasota, FL, Fernandina Beach FL, Toledo OH, Battle Creek, MI, Zinzinnati, OH, Streetsboro OH. Ravenna OH, Akron OH, New Bedford MA, Jeddah, Saudi Arabia, Santiago Chile, Dundee, MI, Deerfield, MI, Carmel, IN and Kalamazoo, MI to name a few.  I can even sing the Kalamazoo song.

I like baseball, golf, girls' broomball and lacrosse. I played lacrosse in college.  I used to watch football but no longer do.  I like TV shows like Suits, Inspector Morse, Inspector Lewis, Arthur,  and stuff on the Discovery Channel and the History Channel that most of you consider extremely boring.  I read lots of books without pictures, and some with pictures.

I love my kids, but there is only one left.

I used to be a Republican but now I'm an anarchist.

I am an Orthodox Christian.  For those of you who don't know what that is, that means that I kiss pichurs and cross myself backwards. If that offends you, too bad.

I am going to blog about things that interest me, and try to teach some of you something as well.  I am preparing a series of articles that won't be so long that your eyes glaze over.  You will probably get mad at me for something I publish, maybe all of it.  I don't care.