Optimization of WWTP at Maize Industry

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We have opened our Waste Water Treatment reactor after 5-years of operation at maize industry because we were facing low pH issue at its outlet and higher COD at outlet than inlet.

The reactor is made of concrete and has no agitation with upward flow.

The lower portion of reactor is getting blocked with sludge in treatment process. 

The plant capacity is of 30 m3/hour but we achieve only 5 m3/hour.

Can anyone help us with streamline operations and inlet streams ration at equalisation tanks? 

How do we optimize the treatment process to avoid filling the reactor with sludge again?

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10 Answers

  2. Dear Mr. Asim, please give more details of your system I may help you to optimize your plant operations. i need to know the quality of raw wastewater & details of your reactor and designed treatment process

    1 Comment

    1. The designed value for system is based on COD of 5000 at inlet, previously the feed COD was more than 5000, the plant having design capacity of 30 m3/day.

      1. Presently the feed stream contains 100 m3 per day of vapor condensate from Light steep water evaporation; which contain up to 1 % max. soluble protein at temperature of 65 degree centigrade having PH of 2 to 2.5,

      2. the second stream is 200 m3/day of starch dewatering clarifier overflow with up to 2 % insoluble starch and 1 % soluble matter including salts etc at PH of 4.5 to 6 depending up on product under manufacturing,

      3. the third stream contains Ion Exchange columns Regeneration waste water from glucose refinery which by volume is 250 m3/day at varying PH from 2 to 14 (Caustic & HCL regenerations).

      4. The fourth stream consists of utilities softeners units regeneration waste water, which varies from 100 m3 per day to 400 m3 per day with PH of 4 to 8.

      5. The fifth stream consists of Vacuum pumps seal water drain at temperature of 50 degree centigrade and volume of 60 m3/day.

      6. The sixth stream consists of toilets, Kitchen & Laboratory waste, which accounts for 20 to 30 m3 per day.

      We have first equalization ponds of 350 m3 each, where water from all streams is mixed together with Air perforated pipes and then caustic is dosed at discharge line of pump to HAD feed, the PH is maintained at 6.5 to 7, the temperature od inlet strean varied from 25 to 40 degree  Centigrade.

      The HAD constructed of concrete material with PVC corrugated bundles of fins at Height of 10 feet and having  cover the volume of approx. 300 m3 of the HAD, from the floor and feed from equalization tank is distributed through 4 pipes from top and distributed from bottom with perforated pipe.

      There is no mechanism for Agitation in this Upward flow reactor as it is designed having no agitator.

      There are connections to recover Bio gas which after moisture trap is used at Gluten Dryer along with LPG as its production is very low to ignite only one burner at 4 psi for 2 to 3 hours a day only.

      Presently we have opened reactor and we are cleaning it as it was full of sludge up to PVC corrugated packing and bad odor too. the quantity is was almost more than 300 m3, which still is challenge to clean. 60 % job is done.

      the outlet COD we measure when HAD was in operation was 8000 and PH up to 3.5, the results are with operation flow rate of 15 m3/hr. if flow increased to HAD, starch came out.

      the above results disturb our Aerobic Activated sludge process and kill the bacteria or reduce the Dissolved Oxygen many times.

      we require assistance to solve the issue and increase the BIO Gas production and decreased COD and Increased PH at HAD outlet.

       

      Thanks

       

  3. Dear Asim,

    It's clear that biological degradation is inhibited (low pH and high COD). This can be due to several reasons, as explained in some previous answers. One possible cause is inadequate mixing. Did you consider adding a mixer inside your reactor (e.g. submerged mixers)? Or increasing the inflow velocity?

    1 Comment

  4. The application of many methods is certainly remarkable. But who I will tell you that sewage treatment should only 0,65 kWh of electric energy for one cubic meter of wastewater ??? Costs are always much higher, plus various "unexpected" situations arise. Our equipment cleans all drains in a single pass in the apparatus of the vortex-wave treatment of wastewater. Processing speed - speed of a flow that produces the pump. After treatment the water can be reused for technical purposes, i.e. possible VODOVOROT TECHNICAL WATER WITHOUT RESET !!! Solids in a filtered upsetting and you can use them ( we do it) as organic fertilizer. Anyone who is interested - write, who are interested in applying - we invite you to our facilities, where there are already these settings.

  5. Dear Kazi Sb  Please provide the line diagram of your treatment process with quality characteristics of influent and effluent so that mid way treatment can be pondered upon.  As such you should use a primary settling tank or equalization tank with some aeration to let the inert material settle and organics float for further treatment.  Zahir

  6. dear Asim Kazi Sahib, 

    your reactor has microbial issues. I suggest you get in touch with Water Care Pakistan.  they can help you with savings from not using caustic to lessening electrical cost and most of all, odor issues.  

    all the best

     

    eros

  7. Dear  Mr.Asim Gul Kazi 

    Following steps the main

    components of the treatment plant were suggested as follows:

    1. .Static or rotary down screen,

    2. Buffering tank,

    3. Conditioning tank,

    4.  Two bilobed reactors,

    5. Aeration tank,

    6. Settling tank,

    7.  Sludge holding tank,

    8.  Sludge thickener, and

    9. Centrifuge                                                                                                                    

    The above components are provided with different types of pumps, air blowers, storage tanks, piping, control and instrumentation system.

    your waste water is only 30 m3/hr so quantity is less, but all the step either large or small is necessary.

    In small plant Biological treatment processes have the primary purpose of removing organic materials from the effluent. Biological treatment process is expected to remove only biodegradable fraction of the organic materials present. Aeration devices in biological treatment reactors should be designed as that they can transfer oxygen at a sufficient rate to satisfy the demand of the biomass and maintain the dissolved oxygen concentration above 2 kg/m3.

    Conditioning Tank,Caustic Dosing Facilities and FeCl3 and Micronutrients Dosing Facilities are the part of treatments,

    FeCl3 and micronutrients dosing facilities are to be designed for adding Fe, and micronutrients (if required, Co, Cu, Mo and Ni) as a nutrient (in the feedline to the reactor). Design average Fe requirement is 5 ppm. Design average concentrations

    for Co, Cu, Mo and Ni are respectively 0.01, 0.025, 0.001 and 0.035 ppm. 

    for detail please find attached herewith imp article and flow diagram.

    Regards,

    Prem Baboo

    1 Comment

  8. One of the BACT process for addressing this issue is to add a simple headworks tot he process so that you treat the water only and reduce the volume of the sludge accumulation. I have recently seen such a system an orbital screening unit with perforated screening plates or wedgewire option and with hydrocyclones.

  9. I can suggest that you take a look at 

    https://www.organicawater.com/ocs-express/?gclid=CPvB5MGPvdMCFVU9gQodAnIOnw

    They have ways to evaluate your operations.

    I also agree with the suggestion by Bob H. and recommend use of a high pressure blower connected to polyethylene tubing with intake above the tank fluid and discharge in two parallel perforated pipes on the "long" sides of the tank PLUS another poly tube at the center, bottom of the tank to circulate the tank fluids thru a centrifugal separator system where about 5% of the circulation fluid flow (containing the sludge) is discharged to a evaporating pond. the sludge will be concentrated by evaporation so it can be further processed. The remaining fluid should be re-injected at the top, center of the processing tank.

    The aeration and circulation should increase processing and, hopefully knock down the COD at the same time.

    1 Comment

    1. Randall .. you are obviously a lot more involved with the actual operational aspects of this type of treatment than I am .. my hat goes off to the 'hands on' personnel that know the workings of the various processes . . thanks for your input . . it sounds like it may actually be a win-win for Asim . one question . any idea of capital costs for making the improvements you're talking abt? 

  10. agitation / mixer in the reactor may provide some relief with sludge build-up problem .. higher COD at the outlet may be result of sludge build-up as well . . mixing / aeration may alleviate .. . 

    2 Comments

    1. Thanks Bob & F H Mughal,

      we understand the importance of mixing as our reactor has perforated pipe with direction of nozzles at bottom, which serves purpose of mixing, they were actually chocked due to addition of nutrient Di ammonium phosphate on advice of supplier WEMS. we are trying to open them and cleaning the system, mean while looking for more options to get more methane bio gas.

      well i have suggestion to add fresh cut grass weeds to reactor as they help us produce more methane gas, what are your opinion, presently we do not have any mechanism to add them.

    2. Dear Kazi sb,

      Bob Hennes has a point. You need to have mixer, a critical link,  to mix and agitate the content of the reactor. In my work on anaerobic contact process research at AIT, Bangkok, mixer could not work for some time, and the reactor gave unacceptable results in terms of COD and VSS.