Bleaching powder dosing for disinfection in waste water treatment plant

Bleaching powder dosing for disinfection in waste water treatment plant

Sources of Informations given below
Manual  http://cpheeo.gov.in/upload/uploadfiles/files/Chapter%206-9.pdf

1. https://www.epa.ie/pubs/advice/drinkingwater/Disinfection2_web.pdf
2.http://jeb.co.in/journal_issues/200710_oct07/paper_04.pdf

 The pilot scale disinfection units located at two different UASBR based STPs have been selected for this study. One of these pilot plants has been constructed after 27 MLD UASBR based STP, Noida (Uttar Pradesh, India) and is based on chlorination using calcium hypochlorite (either slurry form or liquid high test hypochlorite, HTH) with a capacity of 2 million liter per day (MLD). The other 1 MLD DHS-biotower pilot plant, developed by Prof. H. Harada (Machdar et al., 1997), is based on fixed film aerobic process and has been constructed after 40 MLD UASBR based STP, Karnal (Haryana, India). These STPs, based on UASBR technology, consists of preliminary treatment (Screen and Grit Chamber), UASBR and final polishing pond (Fig. 1). A schematic diagram of the pilot plants at Noida and Karnal is presented in Fig. 2 and 3 respectively. The chlorination unit of 2 MLD consists of a sump, mixing unit and baffled contact chamber (3m x 7m) and a specific dose of chlorine was mixed with a separate pipe. The 1 MLD DHS-biotower based on fixed film aerobic process consists of a sump and reactor having plastic rectangular sheets onto which triangular prism polyurethane foams were tiled. Raw sewage after UASBR treatment was supplied to the chlorination unit and DHS-biotower
In case of chlorination unit, initially the bleaching powder was used as a disinfectant from day 1 to day 48 and later on it was found that there was no residual chlorine in the bleaching powder, so the bleaching powder was replaced with calcium hypochlorite as disinfectant after 48th day. The dose of disinfectant was 5 mgl-1 from day 1 to day 16 and was increased to 20 mgl-1 from day 20. The contact time for the reaction between wastewater and disinfectant was 30 min throughout the study.
 Results and Discussion Reduction of fecal coliform: To achieve good disinfection, the contact time and dose are extremely important. A longer contact time is required for complete disinfection to occur. As per Lindsay (2004), a contact time of 30 minutes is a minimum, and if the dose remains constant, the contact time may necessitated to be increased at low temperatures or higher pH to obtain the same level of disinfection. Typical chlorine doses for municipal wastewater disinfection are about 5-20 mgl-1 with a contact time of 30 to 60 min (Lazarova et al., 1999). During this study, 5 and 20 mgl-1 of disinfectant doses for a fixed contact time of 30 min was applied. It was observed that a dose of 20 mgl-1 was very effective for the reduction in indicator microorganism (fecal coliforms). Initially when a dose of 5 mgl-1 was used, the reduction in fecal coliforms count was less than 90%. It may be attributed to the fact that the minimum dose required for the killing of microorganism was not sufficient as there was high chlorine demand due to the presence of high concentration of organic matter and suspended solids in the UASBR effluent. The average fecal coliforms count was reduced from 3.58 x 105 (± 1.02 x 105 ) MPN/ 100ml to nil at a dose of 20 mgl-1 and 30 min contact time (Fig. 4a). Thus the results shows that almost 100% removal of fecal coliforms has been observed after chlorination; however at certain days i.e., from day 7 to day 14 and from day 44 to day 53 (Fig. 4a), the number of fecal coliforms present in the wastewater effluent after disinfection was increased. It could be explained on the basis of type of chemical used for the chlorination. During this period, bleaching powder was used. Later on it was found that the chemical used at the plant does not have any residual chlorine. Chlorination was switched to the fortified brand of the calcium hypochlorite, high test hypochlorite (HTH). It indicated that chlorination was very effective in the removal of fecal coliforms if the regular operation and maintenance (O and M) is ensured.

Iron filter with BIRM media and online air injector

Iron Max

- Chemical free - Iron, Manganese, and Hydrogen Sulfide Gas removal system

Part #

Media Cubic ft.

Tank Size

Pipe Size

Weight LBS

Service Flow Rate GPM

Price

Iron Max-12

2.0

12 x 52

1"

295

10gpm

$2,100.00

Iron Max-14

3.0

14 x 65

1"

474

11gpm

$2,402.00

Iron Max-16

4.0

16 x 65

1"

605

12gpm

$2,515.00

Iron Max-18

6.0

18 x 65

1.5"

870

14gpm

$3,027.00

Iron Max-21

7.0

21 x 62

1.5"

1040

18gpm

$3,274.00

Iron Max-24

10.0

24 x 72

2"

1525

26gpm

$4,192.00

Iron Max-30

15.0

30 x 72

2"

2375

40gpm

$5,782.00

Iron Max-36

20.0

36 x 72

2"

3100

59gpm

$6,503.00

Iron Max-42

30.0

42 x 72

3"

5025

79gpm

$9,511.00

Iron Max-48

40.0

48 x 72

3"

6625

102gpm

$11,920.00

http://www.raindancewatersystems.com/commercialfilters.html Birm does not require chemicals for regeneration, only periodic backwashing is required. When using Birm for iron removal, it is necessary that the water: contain no iron bacteria or hydrogen sulfide. If the influent water has a pH of less that 6.8, neutralizing additives such as Calcite or soda ash may be used to raise the pH. If chlorinating Birm will not remove any residual chlorine in the water. Birm may also be used for manganese reduction with the same dependability as iron removal. In these applications the water to be treated should have a pH of 8.0-9.0 for best results.
Hi tech digital 263/740i control valve. (1.0" connections standard, 3/4" available - please specify). The timer-based unit controls the backwash cycle, to assure dependability and high efficiency.


Air Injector.

Description

Item #

Price

8"x44" min. tank .75 Cubic Ft. media


691-B


$399

Buy Now

Free Shipping!


9"x48" min. tank 1.0 Cubic Ft. media


693-B


$449

Buy Now

Free Shipping!


10"x54" min. tank 1.5 Cubic Ft. media


695-B


$499

Buy Now

Free Shipping!


12"x48" min. tank 2.0 Cubic Ft. media


697-B


$549

Buy Now

Free Shipping

Add a Bypass valve to any Birm Filter for only $29: Buy Now Add an Air Injector to any Birm Filter for only $90: Buy Now For outdoor applications, we recommend you upgrade with an optional outdoor cover ($26.00) and transformer ($20.00) Please specify when ordering.
http://budgetwater.com/birm_filter.htm

Filter Media – BIRM

Iron and Manganese removal

Supplied in 25Kg bags

What it is and how it works

Birm is a black granular filter material used for removal of iron and/or manganese from water in pressure or gravity systems.

It contains an active insoluble catalyst to precipitate iron and/or manganese. Because the presence of iron is most common, iron removal is the usual application for Birm. Under suitable conditions, the iron and dissolved oxygen in water react on contact with the Birm filter bed and, as a result, the iron is precipitated in the form of hydroxide. This is a flocculent material which is filtered out in the bed of Birm. Periodic backwashing flushes out the accumulated iron and the Birm is again ready to perform its function. Birm is not consumed in the iron removal operation.

Advantages

·         No chemicals to purchase for maintenance. Regeneration not required.

·         Iron removal efficiency is extremely high.

·         Negligible labour cost. Only periodic backwashing required once in a week.

·         Durable material with a long life. It lasts 4-7 Years according to use.

·         Wide temperature range application.

Conditions necessary for the use of Birm

Iron Removal

·         No hydrogen sulphide present.

·         Organic matter not to exceed 4-5 ppm as indicated by the oxygen consumed value.

·         Oil must not be present.

·         A dissolved oxygen content of at least 15% of the iron. (Example Iron = 10ppm. Dissolved Oxygen = 1.5 ppm or more).

·         A pH of 6.5 or higher.

Note: The correction of waters having a pH of less than 6.5 can be accomplished by several methods. Provide Aeration.

Instructions for industrial and municipal installations

·         Bed depth: 30 ­ 38 inches.

·         Standard graded gravel supporting bed depth ­14 inches or more.

·         Service flow rate: not to exceed 4 GPM per square foot.

·         Freeboard space: 35 to 50% of bed depth.

·         Backwash whenever the pressure loss through the bed increases by 2 to 3 pounds per square inch. Backwashing is usually complete within 20 to 30 minutes.

Instructions for domestic installations

·         Bed depth: approximately 24 to 30 inches.

·         Standard graded gravel-supporting bed ­ 8 inches or more.

·         Service flow rate: not to exceed 5 GPM per square foot.

·         Freeboard space: 35 to 50% of bed depth.

·         Backwashing is recommended every 7 days to 2 weeks. In treatment of high iron content waters, backwashing more frequently is desirable.If 8 gallons per minute per square foot of bed are not available for backwashing fine Birm, an air wash is recommended. This may be accomplished by drawing air through an injector into the water for backwashing.