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Start - up of TAMTAD Co. Wastewater Treatment Plant...

For more info, order my book ( In Turkish )...
No : 257 - "Operation Procedures of the Activated Sludge Process"...
Dokuz Eylül University - Faculty of Engineering - Tinaztepe Campus - Buca - 35160 - Izmir - Türkiye...
Fax : 90 0 232 353 11 53 and Tel : 90 0 232 353 11 53 / 7102...
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General Information About TAMTAD Co...

The production foundations belonging to TAMTAD Co. which has been working since 1959, were established in Tire, subdivision of the City of Izmir, which has a distance of 80 km to Izmir Port and 45 minutes far away from the International Airport of "Adnan Menderes". The vegetables and fruits are chosen carefully among the specially grown ones that prove the TAMTAD taste. The recent technical knowledge and facilities are being used in the production processes. From the beginning of the purchasing period until to the delivery, specialist food engineers are making controls in every phase of production. The kind of production is changing with the seasons, in addition, the working hours per day. The number of workers are about 200 in the summer.


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Click here for the "TAMTAD"s WEB site

Canned Vegetables and Fruits : It is being taken great pains to choose fresh vegetables and fruits and used only sterilization technique without any chemical preservatives to protect the natural taste, colour and structure of the vegetables.

Ready to Serve Meals : They are produced with the raw materials, aid materials and spices having suitable quality without any chemical preservatives.

Jams : They are presented in glass jars. Fruit ratio in jams from fruits is at least 40 %.

Special Assortments : They are listed as "boiled dishes", "humus", and "white beans with meal".

"Production Portfolio of TAMTAD Co"...
( PS : As of 1992... )
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The old plant was just inside of Tire. New plant was built up 8 km far away from Tire, at the region called "Kürdüllü Creek", in 1988. At the beginning of construction facilities, infrastructure systems related to sanitary and storm water drainage were considered in conjuction with the other facilities. Sewer system was planned according to the future development of the fabric and industrial wastewater treatment plant. Cooling water line was separated from the sewer system and linked to storm - water drainage system.

Wastewater Flow Measurements...

Before design of the treatment plant, wastewater flow measurements were carried out during three years, by using a triangular weir installed at the wastewater discharge channel.

"Flow Measurement at V - Notch Weir"...

First, the maximum weir load (hmax) was determined, then a scale was installed a location before the weir, of which distance was 4hmax. Weir loads were read at 15 - min time intervals.

"Triangular Weir Equation"...

Flow measurements were conducted at full - year period, due to wide production portfolio of the company. Production list has been varied from jam to stuffed vegetables. One of the results obtained is shown below.

"Wastewater Fluctuation for Okra Production"...

After three years, measurements were statistically analyzed and the maximum wastewater flow - rate was determined as 190 m3/day. Domestic wastewater originating from restrooms, showers, and kitchen was selected as 10 m3/day. So, the total wastewater flow - rate was 200 m3/day.

"Variation of the Wastewater Flowrates"...

Wastewater Characterization...

In order to achieve a consistent design, wastewater samples were taken and analyzed during three years together with the flow measurements. According to Turkish Water Pollution Control Regulation, BOD, SS, and pH analysis were conducted.

"Receiving Media Discharge Standards for the Canneries"...

At the beginning, BOD analysis was not achieved due to the lack of incubator and distiller. Instead, COD analysis was carried out. Results were shown below.

"Variation of the pH Values"...

"Variation of the SS Values"...

"Variation of the COD Values"...

After the analysis program ended, results were statistically analyzed and the following values were accepted as the design parameters.
  • BOD5 = 1,568 mg/L
  • COD = 2,652 mg/L
  • SS = 154 mg/L
  • pH = 4.3

Click here for info about "Biochemical Oxygen Demand (BOD) and Nutrient Removal From Food Processing Wastewater"...

Design Procedure...

Flow - Chart...

The wastewater plant consist of two main treatment facilities; (a) Physical treatment units and (b) Biological treatment unit.

"Flow - Chart of the Wastewater Treatment Plant"...
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Design of Equalization Tank...

Description : Flow equalization simply is the damping of flowrate variations so that a constant or nearly constant flowrate is achieved. The principal benefits that are cited as deriving from application of flow equalization are as follows:
  • Biological treatment is enhanced, because shock loadings are eliminated or can be minimized, inhibiting substances can be diluted, and pH can be stabilized
  • The effluent quality and thickening performance of secondary sedimentation tanks following biological treatment is improved through constant solids loading
  • Effluent - filtration surface - area requirements are reduced, filter performance is improved, and more uniform filter - backwash cycles are possible
  • In chemical treatment, damping of mass loading improves chemical feed control and process reliability

Volume Requirements for Equalization Tank : The volume required for flowrate equalization is determined by using an inflow mass diagram in which the cumulative inflow volume is plotted versus the time of day. The average daily flowrate, also plotted on the same diagram, is the straight line drawn from the origin to the endpoint of the diagram (see figure shown below).

"Result of the Equalization Tank Analysis"...

In practice, the volume of the equalization tank will be larger than that theoretically determined to account for the following factors:
  • Continuous operation of aeration and mixing equipment will not allow complete drawdown, although special structures can be built
  • Volume must be provided to accommodate the concentrated plant recycle streams that are expected, if such flows are returned to the equalization tank (a practice that is not recommended because of the potential to create odors)
  • Some contingency should be provided for unforeseen changes in diurnal flow

Operational Data of the Equalization Tank
Hours
Inflow (m3)
Outflow (m3)
Cumulative Inflow (m3)
Cumulative Outflow (m3)
Cumulative Difference (m3)
00 - 01
0.00
8.33
0.00
8.33
- 8.33
01 - 02
0.00
8.33
0.00
16.66
- 16.66
02 - 03
0.00
8.33
0.00
24.99
- 24.99
03 - 04
0.00
8.33
0.00
33.32
- 33.32
04 - 05
0.00
8.33
0.00
41.65
- 41.65
05 - 06
0.00
8.33
0.00
49.98
- 49.98
06 - 07
0.00
8.33
0.00
58.31
- 58.31
07 - 08
0.00
8.33
0.00
66.68
- 66.68
08 - 09
17.40
8.33
17.40
75.01
- 57.61
09 - 10
26.80
8.33
44.20
83.34
- 39.14
10 - 11
23.00
8.33
67.20
91.67
- 24.47
11 - 12
19.30
8.33
86.50
100.00
- 13.50
12 - 13
13.20
8.33
99.70
108.33
- 8.63
13 - 14
15.60
8.33
115.30
116.66
- 1.36
14 - 15
23.10
8.33
138.40
124.99
+ 13.41
15 - 16
21.10
8.33
159.50
133.32
+ 26.18
16 - 17
21.10
8.33
180.60
141.65
+ 38.95
17 - 18
19.40
8.33
200.00
150.02
+ 49.98
18 - 19
0.00
8.33
200.00
158.35
+ 41.65
19 - 20
0.00
8.33
200.00
166.68
+ 33.32
20 - 21
0.00
8.33
200.00
175.01
+ 24.99
21 - 22
0.00
8.33
200.00
183.34
+ 16.66
22 - 23
0.00
8.33
200.00
191.67
+ 8.33
23 - 24
0.00
8.33
200.00
200.00
0.00

As it can be seen from the figure given above, differences between the cumulative inflow and outflow volumes are 66.68 and 49.98 m3. So, the required volume of equalization tank can be determined by summing of absolute values of the differences as follows ;

VEqualization tank = 66.68 + 49.98 = 116.66 m3

There is not need to mention about that theoretical volume of the equalization tank must be increased to meet the factors aforementioned just above.

Continuous Mixing in Equalization Tank...

In continuous mixing, the principal objective is to maintain the contents of a reactor of holding tank in a completely mixed state. Continuous mixing can be accomplished in a number of different ways, including ; (1) in hydraulic jumps in open channels, (2) in "Venturi" flumes, (3) in pipelines, (4) by pumping, (5) with static mixers and (6) mechanical mixers. According to the literature, the completely mixed regime can be obtained in a equalization tank, by applying a power varying between 10 and 30 W / m 3. Continuous mixing in the equalization tank was accomplished by a submerged mechanical mixer having a power of 4 kW.

Start - Up...

Wet Control...

Wet control was carried out for both the basins and the mechanical equipment. First, basins were filled up by tap - water to check out whether leakage occurred or not. Some points were detected causing leakage. Then, basins were emptied and these points were isolated by a wet - isolator, trade - marked "Xpex". Secondly, all equipments (pumps, aerators, mixers, etc.) were started up one by one to control any mechanical failure. Of course, the pipe - lines were controlled as well.

Start - Up...

After the wet control, all basins were filled up by tap - water and the wastewater discharge channel was linked to the physical treatment units consisting of coarse screen, grit and grease / oil trap, and micro - screen located before the equalization tank. All pumps and surface aerators were activated. To encourage the microbial growth, domestic wastewaters were pumped directly into the extended aeration activated sludge aeration tank. In addition, large volume of blood supplied from a slaughterhouse was added into the aeration tank with rescept to increase the volumetric organic load. During the first three days, high amount of foam coloured white, having fluffy structure, occured. That was normal for the start - up period. There was no need to alarm. An anti - foam chemical could have been used to suppress the foam. There are two low - speed mechanical surface aerators in the aeration tank, each of powered by 15 kW - motor. At the beginning of start - up period, just the closer one of the aerators to the inlet structure was continuously operated because of high organic loading at that part, and the other closer to the outlet was automatically activated by a control device getting signals from an oxygen - probe installed closer to the outlet weir of the aeration tank. The dissolved oxygen concentration range of the controller was set up between 2.0 and 3.0 mg/L. To increase the amount of active biomass in the aeration tank, sludge settled on the bottom of the clarifier was continuously recycled to a point of the aeration basin, at which both domestic and industrial raw wastewaters mixed with together.

Control of Microbial Growth...

During start - up period, samples of mixed liquor taken from the aeration tank, were analyzed on the basis of suspended solids to monitor the microbial growth. In addition, they were inspected under a microcsope against the filamentous growth. Besides the suspended solids analysis, SVI tests were continuously carried out. There was no any image indicating the filamentous bacteria. After three days, MLLS concentration of 890 mg/L was found. On the fifth day, it was about 1,200 mg/L. In addition, samples taken from the outlet of chlorination chamber were analyzed for COD. During first three days, COD concentrations of the effluent did not meet the receiving media standards stated at the "Turkish Water Pollution Control Regulation" became active in 1988. On those days, the contractor was taken a sample from the outlet and sent it to laboratory of an university to check - up the treatment efficiency. Results were incredible...! We had met the standards, just after five days, with a relatively low microbial mass. But, my sixth sense was trying to say to me that something was going wrong. What was it...? I knew...

First Problem... "Filamentous Bulking Sludge"...

After the sixth day, something bad indicating bulking sludge was observed at the Imhoff cone. There was a sludge did not want to settle. Sample of mixed liquor taken from the aeration basin was immediately inspected under the microscope. High amount of filamentous bacteria were observed. They were identified as Type 021N and Thiothrix sp. which become predominant under the nutrient deficiency. They are usually considered together because of their similar morphology and many common kinetic and metabolic features. My sixth sense was right...! Why...? Before the construction, I was continuously telling both of the employer and the contractor, "EXTERNAL NITROGEN SOURCE MUST BE ADDED...!". The contractor said me, "No...! Not required...! For the extended aeration activated sludge process, the C : N : P ratio on the basis of BOD, could be 500 : 5 : 1, instead of 100 : 5 : 1...!" I never believed in it just for the start - up period. As a result, we have met the our first operational problem, namely "FILAMENTOUS BULKING SLUDGE"... It was welcome...!

"Bulking Sludge in the Imhoff Cone"...

Characteristics of Type 021N...

Type 021N exhibits a nutritional versatility and is able to utilize a great variety of readily biodegradable substrats and carbon sources, such as simple sugars, alcohols and organic acids. Its affinity to these substrats under low concentrations is high because of low value of the half - saturation constant (Ks). Type 021N can successfully compete for energy and carbon sources during unbalanced growth under nutrient limiting conditions, especially as far as ammonia nitrogen is concerned. It is explained this selective advantage over floc - forming microorganisms by a rapid assimilation and storage of ammonium under these conditions in comparison with floc - formers. This is why Type 021N is often classified as the nutrient deficiency bulking filamentous microorganism.

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Characteristics of Thiothrix sp....

Thiothrix can be found under conditions which also favor the growth of Type 021N, because these two types are metabolically rather close. Thiothrix utilizes many readily biodegradable compounds, especially organic acids but the importance of sulphur metabolism is more pronounced than for Type 021N. The sulphur granules are frequently present in Thiothrix tricomes in situ while in Type 021N, filaments can be observed mostly after the S - test. Thiothrix seems to be an obligate mixotroph requiring reduced sulphur compounds (sulphide, thiosulphate) in combination with readily biodegradable organic substrates. Reduced sulphur and organic compounds can be utilized by Thiothrix either simultaneously or in two phases. For instance, it was observed for one Thiothrix strain a biphasic growth scheme when thiosulphate was nearly completely oxidized without any significant consumption of acetate. When thiosulphate was exhausted, acetate consumption and oxidation of cell - stored sulphur followed the first phase. The nutritional requirements of Thiothrix predict its preferred environment with low fatty acids and reduced sulphur compounds.

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Data About the "Filamentous Microorganism - 1"...
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Data About the "Filamentous Microorganism - 2"...

Solution of The First Problem...

The nutrient deficiecny is most common problem arising in the activated sludge treatment process at which industrial wastewater is being treated. No problem...! Three short - term suppress methods were considered to struggle against the filamentous bulking sludge. First, the equalization tank was operated as "selector" by recycling the sludge from the final clarifier to it. Filamentous bacteria were eliminated by creating "anoxic" conditions in the equalization tank. We had a kind of disadvantage with respect to hydraulic retention time in the equalization tank. In a selector used to suppress the filamentous bulking sludge, should be between 15 and 30 minutes. No way out...! You had to try your opportunities...! Second, urea was added at a daily amount of 3 kg into the aeration tank by the employer, according to directions of the contractor. In my opinion, it was not enough. According to my theorytically calculations, urea dose of 12 kg/day must have been applied into the aeration tank. I knew the "endegenous respiration", of course, at an extended aeration activated sludge process. When you consider the relatively low MLLS concentration aforementinoed just before and recognize the high organic load, you might think that it is not enough time for it at the start - up period. Anyway... Third, aerator the closer to the inlet structure of the aeration tank, was stopped and the other one the closer to the effluent structure of the aeration tank, was started with respect to create relatively anoxic conditions at the inlet part of the aeration tank. The dissolved oxygen - controller was connected to the operating one. After four days, there were no any filamentous bacteria under the microscope. Can you believe in that...? We achieved... How...? By the "ANOXIC CONDITIONS"... An important advice... Do not operate your selector, if exists, under anaerobic or oxic conditions. Just under the anoxic... Why...? Let us see...

Data About the "Filamentous Microorganism - 2"...

Metabolic Selection in Anoxic Conditions...

Metabolic selection under anoxic conditions does not necessarily require alternation between anoxic and oxic conditions. For balanced growth, the substrate is taken up and metabolized directly in anoxic conditions. Of course, balanced growth under anoxic conditions has no practical meaning, but was used as an experimental proof of this phenomenon. In actual activated sludge plants, the alternation between anoxic and oxic conditions is unavoidable when nitrification and denitrification are required. Indications that the removal of available substrate under anoxic conditions may support the growth of floc - forming microorganisms can be traced back to the 1970s. This is similar to discoveries about metabolic selection under anaerobic / oxic conditions - at first the phenomenon was neither clearly separated from the simultaneous effect of kinetic selection, nor properly explained. For instance is was recommended the installation of an anoxic premixing tank ahead of the main aeration basin as one measure to prevent and control filamentous bulking. In terms of correlation between phosphorus content in activated sludge and SVI, the positive effect of the anoxic premixing tank by an increased content of phosphorus is declared. The reason for this increase is supposed to be a local increase in pH due to denitrification which supports the production of calcium phosphate in activated sludge flocs.

"Metabolic Selection in Anoxic Conditions"...

Second Problem... "Fungal Bulking Sludge"...


After the first problem, another one arised caused by fungus. How did we recognize it at the beginning of the problem...? It was too easy... Just look at the picture shown below.

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"Fungal Bulking Sludge"...

As mentioned before, the equalization tank was being used as selector. It was OK...! What did cause the funguous bulking sludge...?

"pH Values of the Raw Wastewater"...

Characteristics of Fungus...

Some microbiologists complain that the low frequency of occurrence of micromycetes reported in activated sludges is because people do not look for them in a microscope. That is true, but microscopic fungi usually form structures not so easily overlooked by careful examiners. The presence of fungi in the biocenosis of activated sludge should not necessarily be detrimental to settling properties. The formation of large and compact activated sludge flocs on hyphae of Fusarium, which is one of the most common genus of hyphal fungi found in activated sludges was described. The formation of activated sludge flocs on the skeleton of branched mycelium of Saprochaete saccharophila, was observed. When bulking by fungi occurs, Geotrichum candidum is, in most cases, the causative organism. This yeast - like organism produces extended dichotomously branching hypae which can interfere with floc settling. Moreover, the mycelium of Geotrichum candidum has a tendency to float, which deteriorates the settling properties even more. An excellent growth was observed at pH values in a range of 5 - 7 and at a temperature range of 15 - 30 °C. The growth of Geotrichum candidum was inhibited, and the bulking problems were cured, by means of alkalization of the mixed liquor to pH 7.5. As its name indicates, Saprochate saccharophila prefers carbohydrates as substrate. When presents in excess, the long and abundantly branched filaments may cause severe settling problems.

Solution of The Second Problem...

At that period, TAMTAD Co. was being worked 24 h/day, as 3 shifts. A day on which I asked a question "What about the pH level of your wastewater at the third shift...?" At the third shift carried out between 24 pm. and 08 am., average pH of the wastewater was 4.5 and the wastewater was being directly discharged into the equalization tank into which the return sludge was pumped. The main reason was that pH adjustment was carried out at the neutralization tank into which wastewater withdrawn from the equalization tank was pumped. The second reason that the average hydraulic retention time in the equalization tank was about 8 hours. The hydraulic retention time in a selector must be between 15 and 30 minutes. But, we did not have any alternative. Of course, if you create an environment of which the pH level is lower than 6.5, you might be awarded by the "SOCIETY OF FUNGUS LOVERS"...! We have got it...! What must have been done...? It was so clear...! We had to adjust the pH level of the wastewater higher than at least 7.5 before discharging into the equalization tank. To achieve that, the pipe - line of the costic dosage - meter was linked into a point between oil / grease trap and micro - screen, which were physical treatment units located ahead of the equalization tank. Namely, we started to neutralize the wastewater before discharging into the equalization tank. At that period, a sample taken from the aeration tank was sent to an university with respect to identify the fungus, microbiologically. They were predominate... But, after one week, they were killed...!

Third Problem... "Nocardia Foaming"...

Operational problems loved us...! In my opinion, to live all main problems at the start - up period, namely at the beginning, has gained us too many important information related to filamentous microorganisms and their elimination. Every activated sludge process has own characteristics which differ from the others. There is no any certain rule that must be applied to all activated sludge processes. Anyway... That problem was caused by low organic loading. The TAMTAD Co. started to work just one shift per day. At that period, the wastewater flow - rate varied between 60 and 110 m3 / day. The design value was 200 m3 / day. The MLSS concentration reached up to about 3,500 mg/L. More biomass, but no more food...! So, the F / M ratio enormously decreased.

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Characteristics of Nocardia sp....

Foam - forming microorganisms F are filamentous microorganisms which have the ability to form foams, i.e., not microorganisms simply trapped in the foams. These filamentous microorganisms have to be able to produce biosurfactants, and they exhibit an increased hydrophobicity of cell walls. The microorganisms which were proved to possess these properties are nocardiaforms, Microthrix parvicella, Nostocoida limicola and possibly Types 0041 and 0675.

"Growth Response of the Filamentous Microorganisms"...

Solution of The Third Problem...

What could have been done...? It was just time to waste the excess sludge from the system. We have started it. The contractor was considered to waste the excess sludge, continuously. There was something to warn...! But, at that time, I have choosen to stop talking any more...! Something which must have been talked was that the daily increments of the wasting rate must have met the criteria of 10 % / day...! Why did I stop talking...? Because, there was an old and diseased biomass in the system since the beginning of start - up. To waste all of them, might be gain us some advantages... We will see... And, we have saw it !!! Try to get a MLSS concentration in the aeration basin between 2,500 - 2,800 mg / L... You will not meet any operational problem... Trust me !!!

Fourth Problem... "Denitrification"...

You must have a dissolved oxygen concentration at the effluent of final clarifier 0.50 mg / L, at least. No way out !!!

Present Status...

Now... The plant is just like restarted - up... The volume of settled sludge in Imhoff cone after 30 - min. was 10 mL/L. The supernatant was not clear that means the effluent quality was too low. Nowadays, there is white excess foam at the aeration tank surface which indicates that the plant is being recovered. On a day, recently, I have read the dissolved oxygen level at the control panel as 2.93 mg/L at about 01 pm. It was 2.54 mg/L at 05 pm. What did it mean...? My sons which are the floc - formers were growing faster. I love them... The daily amount of urea was 2 kg, according to the contractor's direction. I was increased it 4 kg/day. As I mentioned before, according to my theorytically calculations, urea dose of 12 kg/day must have been applied into the aeration tank. In additon, we have decided to recycle return sludge into the aeration tank instead of the equalization tank which has been serving as selector. As I mentioned just before, we will see... Now !!! We have reached a BOD5 concentration at the effluent 6.00 mg / L... It is incredible !!! See...

"Receiving Media Discharge Standards for the Canneries"...