Dear Mr. Asim, please give ...

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

Published April 27, 2017 13:19 by Asim Gul Kazi, Production manager at Rafhan Maize Prooducts Company ltd

Permalink