LU82246A1 - TREATMENT OF SULFURIZED SEWAGE WITH HYDROGEN PEROXIDE - Google Patents

Description

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The present invention relates to a treatment method |! i |, sewage containing sulfur and / or hydrogen sulphide ‘It is intended to remove these compounds. j!

The presence in sewage of sulfur products 5 which are generally formed by reduction of sulphates under the action of anaerobic bacteria has a double disadvantage: the release of foul-smelling odors of a toxic product, hydrogen sul- | furé, and strong corrosion of pipes and fittings

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treatment treatment whether metallic or concrete. ; ‘D Many treatments have long been proposed;

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to remove sulfur products from sewage such as: aeration and oxygenation. j The use of hydrogen peroxide as an oxy- reactant! Dant for the treatment of sewage was recommended by the USP j '5 2,070,656, the oxidation of H ^ S and sulfides by being in itself a well known reaction.

The treatment of sulfurized sewage with hydrogen peroxide has been proposed by French patent 2,126,199 which recommends a treatment comprising the introduction of H2Q2 at a single point in the sewer system, or the entrance to the processing station, which successively includes a pre-conditioning phase where 4- to 10 times the stoichiometric equivalent of sulphide and hydrogen sulphide in water is used arrival drain, then a period of maintenance treatment where 1 to 2 times 25 times this stoichiometric equivalent is used.

This process makes it possible in certain cases to obtain at the entry of the treatment stations a water containing practically no more, sulphides or hydrogen sulphide, but it does not ensure a satisfactory protection ^ of the whole network preceding the sewage treatment plant.

The Applicant has found that to obtain good results; i

generally speaking regarding the protection of the re-J

I bucket only the sulphide or hydrogen sulphide content at the entrance!

The treatment plants, it was necessary that the introduction of hydrogen peroxide was made at several points in the main network i

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*. ρ Ί '", · from sewage water at the treatment plant, distributed evenly over the entire network.

The quantities of H 0 required cannot be fixed at! 2 <-; a priori, they depend in fact not only on the content of sul-j 5 fure in the water to be treated, but also on the characteristics of the;

network in play such as the length of the pipes, the time of J

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average stay, temperature ... j

The tests carried out by the applicant on networks; of sewage during service showed that the best use> '· \ tQ d'H_, 0_ was obtained by distributing its introduction between the di- ί [22 ij towards retained points so that the sulfur content of the waters ! i. | at the entrance of the various addition stations of the H „0 is practically 'i £ d i

nothing. ‘. J

The points of introduction of H ^ O ^ should preferably be chosen so that the treatment is started the most. j upstream possible in the network and that it covers the entire network as homogeneously as possible. i

The network lift stations are places particularly indicated for the injection of HgOg because the function; ! i 20 jement of the PBU injection pumps ^ then be synchronized: with that of the lift pumps, and let the agitation created by j I,!

the lift pumps is sufficient to ensure good homo-J

genization of the mixture. j

All the aqueous solutions of H ^ O ^ can be used to '2.5 carry out the process according to the invention, but it is particularly i! ! advisable to use 50% solutions which leads to a lower cost.

i The introduction of 1 * H_0_ into water pipes Ί 2 2 of sewage can be done by any appropriate means, the use of 3¾ laying pumps being particularly recommended.

The following examples illustrate, without limitation, the advantage of the process according to the invention. Example 1 is a comparative example where the introduction of 1 * ^ 02 was made at a single point in the network; Example 2 is an example of a practical embodiment of the treatment process with H 0_ of sulfurized sewage ^ with the introduction of hydrogen peroxide at several points in the network '·: (.. · * IXZj γτι --------; .....

• ’· · j of sewage water distributed in a regular manner over the whole j of the network ^ developed by the applicant. i - EXAMPLE 1! - ^ j. A network of egos supplying a bio-j 5 logical wastewater treatment plant is made up of three lifting stations B, C, D receiving wastewater from the different districts of a city, water | from these three stations meet at a bearing station i A by means of the pipes; ! ! '' - Gravity BA of length 1650 m and diameter 0.315 m 1C - CA comprising two parts: a pressure pipe i of length 665 m and diameter 0.25 m, then a gravity section of length 9D5 m and 0.25 m in diameter - DA with two parts; a pressure pipe 1 of length 900 m and diameter D, 355m, then a section - *

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15 gravity lesson of length 1.690 m and diameter j 0.355 m * d

Central station A is itself connected to the wastewater treatment plant! ration through a pressure pipe of length: • 1,870 m and diameter 0.40 m. The station receives other waters of 1 to 2C tastes, but the controls carried out at its entry were unique-iment on those coming from the A * post

During the test period, the water from station i A has a flow rate of 3,000 to 4,000 ml / day, and their characteristics in the absence of oxygen treatment are as follows:

25 - temperature .............. 19 to 22 ° C

- pH ...............'........ 7.4 to 8.4

! - redox potential .......... - 60 to -400 mV

Î 1: - sulfur content at! the entrance to the lift station A: 0.52 mg / l on average i - sulphide content at 3C the entrance to the treatment station: 4.6 mg / l in mo · I · "yenne i

The sulfide assays are carried out potentiometrically immediately after the samples have been taken ^ using a! selective sulfide electrode.

j | Treatment with f ^ Og with the introduction of hydrogen peroxide into the central lifting station A was carried out during

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"42 days by introducing 5 ° ^ ° after 1 (32 Pumps of * ε1 ^ νε“, using dosing pumps. The pumps at H ^ 02 are synchronized with the sewage lifting pumps that work: <intermittently.

5 Intermittent operation leads to an average residence time of 100 minutes in the outfall for the period considered.

Water samples were taken from the bSche before the lift pumps and from the outflow from

the arrival of the station. J

\ ’10. The operational conditions and the results obtained: during certain periods of this test are collected in the ta-’ j | I i

j bleaux I and I (continued) attached. I

After a walk of two days without the introduction of H ^ O ^ where a sulphide level is noted at the entrance to the lifting station A varying from 0.32 to 0.61 mg / l, and at the entrance of the station from 4.2 to ï '· 5.2 mg / l, the 3rd day is introduced in A, for a treatment of cons; i prior addition, 22.9 mg / l H ^ D ^ $ 50, approximately 2.5 times d,

The stoichiometry of the oxidation reaction of sulfur to sulfur.! | _the H-0 content is the 4th day lowered to 5.7 mg / l, then the 7th '10 day raised to about 8.8 mg / l · of H ^ O ^:

As the sulphide level at the entrance to the station is irregular and too high, the 9 'content is increased on the 9th day to around 19 mg / l, which content is maintained until the 18th day.

During the test, we note an average consumption of I ^^> 5 30Γ, ί of 15.1 g per m3 of water entering the station, the sulphide content i at the station entrance varying considerably .

I The test was continued for more than a month 'with variable H2D2 contents, and it was found on the 42nd market day read' with an H0 content of 36.1 mg / l H 0_ 50 / °, the sul- content. i 4 4 2 4 30 f ure · has been reduced to less than 0.1 mg / l, as can be seen in Table I (continued).

iThis result 'which is satisfactory as regards the sulphide content at the entrance to the treatment station, is obtained | . ! with an amount of H_0_ corresponding to 3.9 times the stoichiometry j l Z Z j 35 of the oxidation reaction, but on the other hand, such a process does not eliminate anything in the pipes preceding the lifting station! 1 odors and corrosion.

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• '- ·' · 1 - example 2 I

A network of sewage systems is made up, as shown in example 1, by a network of pipes grouping together in the substations. i bearing B, C, D themselves assembled at station A, and by another.

5 network grouped together in one station E. The pipes from A and Z meet at the entrance to the treatment station.

The characteristics of the BA, CA, DA and A-station sections! are those shown in Example 1, and item E is sound.

side connected to the pipeline coming from A just before entering '1C the station by a pressure pipe of length 850 m and from! 0.25 m diameter. | '

During the test period, the waters arrive at the station with a total flow of 6,700 to 7,300 m3 / d, of which 5,500 to 6,000 · m3 / d from station Ai and their characteristics in the ab- j 15 oxygenation treatment are as follows: | 1 · - temperature ................ 20 ° 5 C to 23 ° C d - pH ................... ...... 7.55 to B, 50!

- Redox potential ............ - 260 to - 400 mV

. - sulphide content at the entrance of station A ........ 0.35 mg / 1 on average 20 - sulphide content at the entrance to stations B, C, D, E. less than 0.05 mg / l - sulphide content at the entrance to the station ..... 3.43 mg / 1 on average

The sulfide assays are carried out potentiometrically immediately after the samples have been taken using a selective electrode. sulfides.

-25 A treatment test with H ^ O ^ with the introduction of peroxide simultaneously into the 5 bearing stations A, B, C, D, E. was carried out for 9 days by introducing H ^ O ^ $ 505 after the lift pumps using dose pumps. "The pumps at H ^ D ^ are synchronized with the sewage lift pumps which operate intermittently.

Operational conditions and results obtained ï | are collated in table II attached.

is initially introduced in station Ä, then gradually in the other stations, the sulphide content

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---- ---- "----------------------------------------- - ------ / 'entry of station A is initially 0.35 mg / l, then becomes lower than 0.05 mg / l in two days, and in parallel the content of "J sulfides at l The entry to the station, which averaged 3.4 mg / l, just before starting the injection of F ^ Oj "becomes less than 0.05 mg / l when the injection d 'F ^ O ^ was carried out in the five stations A, B, C, D and E. **

It is noted that the use of the process perfected by the de--, manderesse leads to practically zero sulphide contents, j lower - at the limit of their analytical detection, 0.05 mg / l! . t 1C across the entire network. This treatment therefore results in the complete disappearance of the odors, and eliminates all corrosion for the whole of the network. ί

During this test, the average consumption of HgO ^ $ 50 was: 36.5 g of Ho0_ $ 50 per m3 of water entering the treatment station, and made it possible to reduce the content in sulfides at the entrance to! this same station from 3.4 mg / l to less than 0.05 mg / l.

Λ /, »« «-V L_j L · ........................ — ........- ..... ...... ............. '..............' * '"........ Μ”. · ·*·· He . .....

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TABLE I

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Example I x Introduction of ÎM- ^ O ^ at a point in the network ”______1 _

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(* ί Posta of bearing A χ Station) ”. . * * ““ “'“ -------------- 1 Rate of su T-); (Day j Hour: Sul- rate * Rate of χ fures to the en) j

! * * T11? 53 è 1, e, n- * treatment in x entry in mq / l) S

!,) 1 * entry in mg / 1: mg / l H? 0-, 5θ £ χ) i

<x ---------------------------------------------> J

• ‘i · 1 *; 11h2 °:, 4.4! :] l4h40 I, x 4 2 'x d15h 10 »0.51, ·. r {(: | 4:10 pm: 0.61 χ. {(x I t · '' · 1 (2 x jl0h20 x 0.32 \ l! j- • i (X I4h25 xxx 5,2 ")! I jv. xxxx \ 'i 3 x 9h50 x 0.70 * x 22.9 x';).

| ; i ’‘ i 1:50 x. . X · "- x o’j ·)! | j * 4:05 pm * x "x 2.6) d; x 1 X x î 1

; 4: 9:55 a.m. 1 0.57 x 5.7 'x. ) I

i (t 'j 12 hÜ □ xxn, i 7 \! i; 1 ^ 50x. * „; i: is -) 1' 1 XX) 7 x 1:50 pm xx B, B x * ï XX) (8 x 9hOD xxn , 57 \ (x 10:45 x x. Î 2.86 (X 11:30 X 0.33 x π X) (x 12:00 x x. · N. \

(, 1SM5,!. J 3 ^ 64. J

J x 4:35 p.m. * X 8.2 x 4.94) i, 1 * X X x); (9 X 5h30 x * xnt ~ r jp \! (. 7h30. I. · I * i- - j 1 9h3D ”> 1.6 i · (t 10h15 x 0.57 x“ x Λ; - ( “X: 11:15 am x · xn., 3] <· i - j 1 3:55 pm * '* 19.2 x 2 ^ 55) (x 1BhOO: t“. X. 3,28} (x 9:45 pm x,. N * o, 26) * J xx) (10 x 6M0 I x "x · 6.24);! 'X 11h10 X, n, 3.04)'! l" 1 * · * "* 1.48) x 9.30 p.m. XX η X · ^ 0.1) 1}.. 1 · * * i) • (11 x: Bh45 x, b X'5.7) jx 1DK30 x, "'0.26 ·) U (__îJ_ ? ........... x ί J; ——j -: .8 ^ '· j «> j -' j | '......” "“ "*' | / ' "'. i TABLE I (continued.)'

Example I * Introduction of * * ^ at a point in the network. 1). (: -ï -—-— yj I | j: Bearing station A χ Station) j (Day: Time: Sul- j rate J Fures rate ^ rln- j ') 1 * TU ^ e3 to lf ^ n ": Treatment in: entry in raq / 1) J l * entry in mg / 1 t mg / 1 Η? 0? 50%:) sj î ----------------- -------------- j ---------------).

| * 12h00: t 0 (breakdown): d; f 14 'HÏSn' * 1S> 2 * -4 ",") (j uhBo,.; z% j {; '"* · °°;.! i3;? i]! 1 -Jhnn' 1 15,5 1 6.03! (.X 12h0ü: j "m 2 62 1 (: 22h00: tw, 0 * 73) S 17 * 7hD0 * ί" ί 4.28): 10.30am;:. "X \ 43 (: 21b30 :, „T D, 30)” * 1: t \ (1B: 7h00:: · n χ 3.95) j ...... î. .1.2.hD ° ..] ...... ... * *: 0.98) <30; ..................... y;, Y "" 1 # î * 1 ", 2.88 ) S * 5:35 pm 1 * "t 3.67); * *: x} 39.: Bh5 ° * t Π x 4.45 (! 2:35 pm * 't η X 0.80)' i ÎS * t" χ 0.62 )! *] 7:45 am:: “to, 39) D * 6:00 pm x, 3ß 1 χ) lt χ x. \ {42 χ 8:50 am xt„ X 0 1) * 11:35 am: x “x fro 1 (: 3:00 pm x: ti t ^ 0 * 1) - · J 18 ^ 00 xt ^ 0.1). (-: -? - î -----? _ t) '/ | i-'.. 'it II t

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’- '. TI TABLE;

Example 2 ï Introduction of various points in the network ^ \ ‘‘ ____ Ε5Ξί ^ _Α ______ * Ρ ° 5 ^ ε: Station 1 Station: Station: Station); I (!! Cough of) Rate of) -------: ------- 1 -------; --- Ë ---- Cough d2 \ · (Day * Hour * sulfide! treatment-) Treatment rate in mg / l Sulfide î. ) to the en-) en) ^ 2 ^ 2 ^ 0 ^ * to ^ -l’en- '; ; /)) sorts in * mg / l *: sort in |; t j)) mg / l: H202 50¾: J:: mg / l J; : · "Ί -; - = -: -> - i - <- i-î-) 1 1; Sh3o;:;’;; 2,1 j.

:, 4hC10:::: · d, <) 3.30pm) * '* 1: 4 s l d d) 16h00 *)) 39.3 d d | ; ) j: (2: 10.30am: 0.34! "ii, j 0.30) · (; 1 6h3D: 0.36:": ":. · 0.24) j 3) 10.30am) î 1.:: d 77: 1 d ') 4:30 p.m.) 4) 0.05) 18, B))) ")) 0.08 ^) (4: 11 h3D: <0.05:"': ·.!! " 'ί i 0.06) j (·: 16h3D: 0.06: 27.5::: M:: {0.05)! î 5; 8:30 am)::; <0.05? ') _14h3 □) <0.05 "· *" · · <Dj05' \) 4.30pm) <0.05) 26.7) .13)) ")) <0.05 ') (8: 11.30am: 0.06: n: ":: 131: 40.6: 0.9) \ (: 3:00 p.m .:: 1, 55: 1": 72.5: ":": / 0.05) j (: 5:15 p.m .: :. <o, D5) | ! 9 d 1 ohoo) <0.05 d ")"; "; »J« j <o, bone? {• (îiÎIftSSï <0.05: "33", 8 * "· *" î45'1 î <0.05>! (10: 11 hOO: <0.05: n: ji: ": 50.5: ": <D, 05) · '(: 2 p.m. OD:: 15.2:": ":": 35.8: (0.05)! (: 3.30 p.m .: <0.05: ": 26.1: 21 : "::)>! l1) 8:15 am::": ":": ": 0.06? f il4hl5i)") 45.3 dd I - I, d 15h 15: 1 "!": 26.1: ":": <0.05; j) 4.30pm) <0.05) 15.5) 32.1) "]") ")) <0.05d (12: 10.30am::"; ":". "! n; <0.05) j (: 15.45: <0.05: ": 25.3: 26.7:": "': <0.05) ji S15: 11.00: <0.05:": 16.8: 63: ": 0.42? j t * 4:00 p.m. <0.05; 18.55:: "* '": {| i) 5.15pm)) ")" j ") Π) Π d <0.05d} · jC 16: 9h00: <0.05:": ":": ":": <0.05 I {: 15h00: <0.05: ":": ": 76:": <0.05) i ï: 4.30 p.m .:: '": 18.9:": ":": <0.05) ί [17) 11 hoo ) <0.05 d ")" * ":."; "; <O, os?

| }. fi4hi5; ) "j") "j" j "; <0.05J

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Claims (3)

1. Process for desulfurization of sewage water containing sulfur and hydrogen sulfide with hydrogen peroxide, characterized in that the hydrogen peroxide is introduced in several! 5 points in the sewage supply network to the treatment station distributed regularly over the entire network. 2. Method according to claim 1 wherein the distribution of hydrogen peroxide ’J between the various points of introduction is such that! r the sulphide and hydrogen sulphide contents of the sewage j * 1G at the entry of the various points of addition of H ^ O ^ are practically zero. j 3. Method according to one of claims 1 or 2 wherein 50% by weight of hydrogen peroxide is used. \ .A Ά v \ v -v. \ __ / 'v__ ·· .. I · ft «r