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Item 4BCITY OF SOUTHLAKE MEMORANDUM (June 17, 2014) To: Shana Yelverton, City Manager From: Robert H. Price, P.E., Director of Public Works Item 4B Subject: Approve an annual agreement for providing odor control treatment at lift stations with Premier Magnesia, LLC in the amount of $134,500 Action Requested: Approve an annual agreement for providing odor control treatment at lift stations with Premier Magnesia, LLC in the amount of $134,500. Background Information: Since the construction of the Shady Lane and Lonesome Dove sanitary sewer lift stations in 2000, the city has had to treat the wastewater to prevent hydrogen sulfide production in the sewer system from affecting the residents of the Kirkwood Hollow neighborhood. Premier Magnesia has been providing this service for Southlake and Trinity River Authority since 2006 because previous attempts to control the hydrogen sulfide with other products were not successful. Under the proposed agreement, the cost per gallon will increase 5%, from $2.55 to $2.68 per gallon. Premier Magnesia is a sole source provider and patent holder of this technology. An additional benefit to this technology is the prevention of grease buildup in the lift stations eliminating the need for City crews to remove and dispose of excess grease. Staff is recommending that Council accept the proposal offered by Premier Magnesia, LLC to guarantee a rate $2.68 per gallon for their services for a 12-month period with an estimated annual cost of approximately $134,500. Financial Considerations: Funding for this program is available in the current operating budget of the Waste Water Division. Strategic Link: The annual purchase agreement for the magnesia treatment of wastewater links to the city's strategy map relative to the strategic focus area of Performance Management and Service Delivery. The specific corporate objectives that are met by this agreement include: Providing high quality customer service by eliminating odors released in the collection system and optimizing the use of technology with state of the art treatment of wastewater. Citizen Input/ Board Review: N/A Legal Review: None Alternatives: The City Council may approve or deny the agreement to provide odor control treatment at lift stations. Supporting Documents: Annual Contract Pricing Renewal Letter Patent Documentation Staff Recommendation: Approve an annual agreement for providing odor control treatment at lift stations with Premier Magnesia, LLC in the amount of $134, 500 Staff Contact: Robert H. Price, P.E., Public Works Director Chuck Kendrick, Deputy Director of Public Works - Operations Q Q DOD Q QQOQ fl MAGNESIA, LLC May 21, 2014 Chuck Kendrick Public Works Operations Manager City of Southlake Phone (817) 748-8080 Fax (817) 748-8103 ckendrick@ci.southlake.tx.us Subject: 2014-2015 Thioguard — Magnesium Hydroxide Pricing Chuck: Pursuant to your request for a renewal of the annual contract for Thioguard, I am submitting this letter to update you on the terms of the agreement. You may submit Purchase Orders either on a per load basis, or a Blanket PO may be issued for the duration of the price in effect. The price per gallon for the upcoming year will be $2.68 effective July 1st through and ending June 30tn 2015. Supporting documentation for this price increase is attached for your review. At the current combined rate of usage for Lonesome Dove and Shady Lane of 125 gallons per day, plus or minus 10% for seasonal variability, estimated annual costs are between $110,048 and $134,502. Premier Magnesia very much appreciates your cooperation and looks forward to a continued long- term relationship as a quality supplier. Sincerely, Mary P. Evans South Central Regional Account Manager Premier Magnesia, LLC Thioguard TST Phone: 903.245.6316 20108 CR 186 Flint, Texas 75762 Email: mevans@premiermagnesia.com Databases,, Tables & Calculators by Subject Change Output Options: From,. I. 2011 : I linclude graphs Data extracted on: April 11, 2014 (10:30.12 AM) Producer Price Index Industry Data Series Id: PCU325--- 325--- Industry: Chemical mfq Product: Chemical mfq Base Date: -98412 27 70' ( 2014 I 240 01l11 05l11 09l11 01l12 05l12 09l12 01l13 05l13 09l13 01l14 Month Download, 2 .xls Year San Feb Mar Apr May ]un ]ul AugSep Oct Hov a+ec Annual 2011 242.6 245.0 247.6 250.2 252.8 253.4 255.1 255.2 256.7 255.9 255.6 254.7 252.1 2012 258.4 259.7 261.7 262,0 262,D 259.6 259.6 260.2 259.9 260.8 259.9 259.3 260.3 2013 262,E 264.7 265.0 265.3 265.1 265.5 265.2 263.9 262.6 262,3 261.7 262.6(P) 264.D(P) 2014 266.2(P) 267.4(P) 266.8(P P : Preliminary. All indexes are subject to revision four months after original publication, p0 E PETROLEUM S& OTHER LIQUIDS OVERVIEW DATA - ANALYSIS & PROJECTIONS I GLOSSARY, FADS Vlew History: 4 Weekly ❑ Monthly Q Annual Download Data (XLS File? Weekly Midwest No 2 diesel Ultra Low Sulfur (0-15 ppm) Retail Prices Dollars per Gallon 3.96 3.94 3.92 3.90 3.88 3.86 3.84 3.82 3.80 Midwest No 2 Diesel Ultra Low Sulfur (0-15 ppm) Retail Prices (Dollars per Gallon) 2011 AVG 2012 AVG 2013 AVG 2014 AVG Midwest No 2 Diesel Ultra Low Sulfur (0-15 ppm) Retail Prices (Dollars per Gallon) 6 .mil �!�'11111Fl� � s �� CHEM/GALS, LLC June 1, 2010 300 West Barr Harbor Suite 250 West Conshohocken, PA 19406 Tel: (610) 828-6929 Mr. Chuck Kendrick Fax: (610) Deputy Director of Public Works - Operations Department of Public Works — City of Southlake 1905 E. Continental Blvd. Southlake, TX 76092 Re: Premier Chemicals, LLC's THIOGUARD® Magnesium Hydroxide Slurry Proposal to City of Southlake Dear Mr. Kendrick, I have been asked to provide you a brief description of the claim coverage for U.S. Patent No 5,833,864, entitled METHOD FOR THE REDUCTION AND CONTROL OF THE RELEASE OF GAS AND ODORS FROM SEWAGE AND WASTE WATER, (the "'864 Patent"). The patent relates to using magnesium oxide or hydroxide to control odor in municipal sewerage or wastewater. The '864 Patent includes 26 claims directed towards controlling odor in sewers by adding magnesium hydroxide or magnesium oxide. For example, claim 1 broadly claims controlling odor in municipal sewerage or wastewater that includes at least one compound which can be reduced to form hydrogen sulfide. Odor is controlled by simply adding an effective amount of magnesium hydroxide or magnesium oxide to the municipal sewerage or wastewater. I have included a copy of the patent with this letter. Premier has spent a great deal of effort, research, time, trial and error, as well as significant funds, in order to obtain the patent rights described above and to develop a product of the quality that our customers require. We believe the efforts expended to obtain such patent is indicative of the effort our Company will put forward to insure the City of Southlake will receive a competitive, efficient and high quality product that will produce superior results. I hope that this helps in your understanding of Premier's patent position, however, if you wish to discuss the enclosed or have any questions please do not hesitate to contact me. Very truly yours, Stephen A. Becker Vice President, General Counsel and Secretary cc: P. AN M. Madolora T. Miller THIOGUARD PATENT LTR. United States Patent (191 Miller et A [54] mu, MOD FOR THE REDUCTION AND CONTROL OF THE RELEASE OF GAS AND ODORS FROM SEWAGE AND WASTE WATER (75] inventors: Thomas M. Miller, Walnut, Calif.; Mark A• Shand, Findlay, Ohio [73] Assignee: PSC Technologies, Inc._ King of Prussia. Pn. [ m ] Notice: This patent issued an a continued pros- ecution application filed under 37 CFR 1,53(d), and is subject to the twenty year patent term provisions of 35 U,S,C. 154(a)(2)• [21] Appl No..: 690,502 [22] Filed: Jul. 8, 1996 Re4nted U.S. Application Data (63] Coutionation of Ser No. 386,735, Feb. 10,1995, nbandnned [51] Inc C16 .- »...-» ••,...». CO2F 1/66, CO2F 11/00 [52] U.S. Cl..,.M..-..m.,•.T.• . 2101724; 210r749; 210/9 3; [58] Field of Search ....,_._...-..._._ .M, .., 210R24. 749. 2101916.903 [56] References Cited U,S, PATENT DOCUMENTS 2,852,584 911958 Kline . ....... ._. 2101916 3,080,253 311963 Dietz et al,. . 3,3T1,271 4/1968 Caen 210/45 3,697,322 10/1972 Lea et ol.~ 3,705,098 1211972 Shegbetd et al M» .M.••.•.,,•••-• 210163 3,862A51 111975 Sprits ct al. . 3,974,783 811976 Flynn .- ,»,., ».......••...•.. • 11019 4.118,3I9 1011979 Miynnob= ct al, .•, ............... 2ID51 4,125,466 11/1978 N iyanoh= et al ..•.. , ....•,.-.• 210167 4,169,906 1011979 I1allstrOm et al. , 4,456,05 6/1984 Albmesa et al• - 4,615,918 10/1986 Reicbert et al. - 4,668,541 511997 Fagedund . 4,67%315 611997 Memr3er et. ol, . l - g1gHi' STORAGE TANK OR DRUM IN 1111 VI IN 11 H 11111111111 IN UP 1111111 [l1] Patent Number; 5,833,864 [45] Date of Patent: *Nov. 10, 1998 4,675,114 6/1987 Zagrai et al ,.••.,.. , •- •.--•.•• 2101666 4,710,404 1211997 Reichert et al 4,786,525 1111998 Kayser et al. . 5,220,995 711993 Storer .... .-- 210191.7 5,246,641 9/1993 Perrin et al. 5,422,015 6/1995 Angell zion51 FOREIGN PATENT DOCUMENTS 1326682 4/1963 France . 424919 311935 United Kingdom - 2123516 211984 United LGngdom ()TM PUBLICATIONS Excerpts from ASCE Manuals and Reports on Engineering Practice —No. 69 titled "Sulfide in Wastewater Collection and Treatment Systems". Davis Process Division of Dais Water & Waste industries, Inc.; Process Division Techtucal Bulletin No. B-401. Bimx- ide ... the natural solution., APreprietary Product Designed to Promate Nammlly Occwming Process Within Wastewater Collection and Treattneat Systems Which Elltuinnte Order Producing Compounds. Sewer Corrosion Control and Rehabilitation, County Sani- tation Districts of Los Angeles County, 5 Pages. Caustic Spray For Sewer Crown Corrosion Control, by Jamie Balda. 11 Pages. Microbial Energy Generation/Oxidation of Inorganic Sub- strates. pp. 158--159. Preparing Collection Systems for Water Conservation, pp- 52 -57. Water Environment & Terlenology, Aug, 1993, (List continued on mart page.) primary Ewrniner—Nail McCarthy Anome)l Agin; or Firm—Ostrolenk. Faber, Gerb & Soffeh, LLP [57] ABSTRACT A method for reducing and controlling the formation and release of add gases and odors associated therewith. par- ticularly from hydrogen sulfide, in sewerage or waste water, wherein magnesium hydroxide and/or magnesium oxide are added to the sewerage or waste water. 26 Claims, 3 Drawing Sheets 2 4\ 3 pH = 6 8, H25=0-3 porn pH =9.1, H25 - 0,07ppm DIRECTION OF FL.OW 5,833,864 Pale 2 917HER PUBLICATIONS Metals Meetlheir Match pp. 69 73, Water Environment & Technology, Sep, 1993. Product Reportl5urfactants for household detergents—pat- rochernical raw materials and uses, pp. 40-41 & 46, MEN, inn. ?A,. 1994, Generation and Control Sulfide in Filled Pipes. by Dr. Richard D. Pomeroy, Pomeroy and Associares. Pasadena, Calif.. Frmn Sewage and industrial Wastes. col. 31. No. 9. 1959, Process Design Manual for Sulfide Control in Sanitary Sewerage Systems. U.S. Environmental Protection Agency Technology Transfer. Oct. 1974. 9 Pages. U.S. Patent Nov. 10, 1998 . Sheet 1 of 3 LL 578335864 Uy = 2 O cQ cD tit hl O r z Lu Lu a- O M m M D d cl � W D Cn COW O 2 2 z I� p 2 a u- O U C,Q � LL LL LU Lr� U.S. Patent Nov. 10, 1998 Shee L a Q Gi rn as 00 r�- r- w Lu �1 C� LL t ,r a a w 2 n w 0 Mr�-0M M cvT-o�aar U.S. Patent Nov. 10, 1998 Sheet 3 of 3 598331,864 co 6 u-, r— 0 co 2 PE co - - 5,833;864 METHOD FOR THE REDUCTION AND It is also an object of the present invention io provide a CONTROL OF TKE RELEASE OF GAS AND method of maintaining a level of hydrogen sulfide which is ODORS FROM SEWAGE AND WASTE below an acceptable level. WATER It is a further object of the invention to provide methods CROSS-REP13RENCE TO RELATED 5 of reducing or eliminating odor associated with Waste water APPLICATIONS or sewerage, This application is a continuing application of U.S. Sec, It is also an object of the present invention to provide a No. 0888035 filed Feb 10. 1995 now abandoned method to minimize the formation and release of both hydrogen sulfide and ammonia in waste water or sewerage. BACKGROUND OF TAP. INVEbrIION 1, Feld of the Invention The present invention relates to the control of gaseous release and of odors associated with sewerage and waste water and more particularly, to the reduction and control of the release of acid gases, such as hydrogen sulfide. from sewerage or waste water, 2. Description of the Related. Art Sewerage and waste water gearrally contain sulfates and other contaminants which, upon reduction. become (directly or indirectly) gaseous compounds which are released gen- erating unpleasant odors. For example. sulfates are reduced to sulfides associated with the release of hydrogen sulfide gas. The reduction of sulfates can proceed by the action of sulfate -reducing bacteria including Derulfovibro sulfricans, Hydrogen sulfide and other acid gases which are released include potentially dangerous contaminants and lead to unpleasant odors. Several methods have been proposed and used to control the release of hydrogen sulfide, These include methods which reduce the growth of the anaerobic bacteria or which chemically bind sulfides. However, these methods have drawbacks. such as high costs, implementation difficulties and safety concerns. In particular ferrous and ferde chloride (iron) and liquid caustic soda (sodium hydroxide- pH 13-1¢) are currently added to sewers to control sulfide generation and catrosion. The iran is added continuously to bind the sulfide as a nonsoluble iron sulfide precipitate. Caustic Coda is gcaerally added semi -weakly to provide a thirty minute, high pH, shock dose to the anaerobic bacteria_ The addition of caustic soda acts by neutralizing the sulfuric acid which has already been formed by the bacteria, inac- tivating and destroying the bacteria. and limiting the forma- tion of new colonies of bacteria. The use of caustic soda has been found to have several drawbacks, Fast, caustic soda only has a bsnporary effect on the bacteria. Second, caustic soda is hazardous and is highly toxic to humans. Sven a small amount of caustic soda can cause permarent blindness. It is expected that in the future the generation of hydrogen sulfide (H2S) will increase, particularly as more municipali- ties adopt water conservation programs that include the installation of low -flow plumbing devices. As a result of the reduced flows in such systems, water may be retained longer in the pipes, wet wells and force mains of the colleciion system; damming caused by settled solids and grease may increase; and less dissolved oxygen (DO) may be present due to increased biochemical oxygen demand (BOD). Absent the teachings of the present invention. all of these changes might otherwise exacerbate the problems addressed by the invention. SUMMARY OF THE INVENTION it is therefore an object of the present invention to provide methods which are safe and effective for controlling the formation and release of acid gases. particularly hydrogen sulfide. 10 It has been found that the formation and release of acid gases, particularly hydrogen sulfide, which are associated with the unpleasant odor of sewerage and waste water can be controlled or eliminated by introducing magnesium hydrox- 15 ide andlar magnesium oxide into the contaminated watCL Moreover. It has surprisingly been shown that magnesium hydroxide is able to maintain a pH level which minimizes the levels of both hydrogen sulfide and ammonia. Further, the levels of hydrogen sulfide and the pH of the contami 20 aaLad water can be maintained at an acceptable level for a significant period of time. Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings. 25 BRIEF DESCRIPTION OF THE DRAWINGS For the purpose of illustrating the invention, there is shown in the drawings an embodiment which is presently preferred; it being understood, however. that the invention is 30 not limited by the precise arrangements and instrumentali- ties shown. FIG, 1 is graph of the relative concentrations of hydrogen sulfide and ionized hydrogen sulfide at various pH levels; F103 2 is a graph of the pH level and aqueous sulfide level 35 after the addition of magnesium hydroxide; and FIG. 3 is a diagram of a representative configuration for the addition of magnesium hydroxide and/or oxide to waste water or sewerage, 40 DETAILED DES(RIMON OF THE INV=ON It has been found that the addition of an agent including magnesium hydroxide (ivMg(OH)2), and/or magnesium oxide as (MgO) to sewerage or waste water which is contaminated with compounds which can be reduced to acid gases, reduces or eliminates the release of these gases and the odor associated therewith. The addition such an agent to sewerage or waste water is 50 able to alter the pH of the solution into a preferred range of approximately 7.5 to 9,5, and to maintain pH in that pre- ferred range for extended periods, The amount of the agent needed to achieve the preferred pH varies with the amount of water to be treated. Monitoring pH of the treated water $5 during addition of the agent is recommended so that the operator may increase or decrease the amount of agent as necessary., In general. the fraction of hydrogen sulfide relative to ionized hydrogen sulfide which is present in solution is 6a dependent on the pH of the solution. It is desirable to reduce the level of hydrogen sulfide which is not ionized so as to reduce the unpleasant and harmful odors associated there- with. As discussed in more detail below, applicants have discovered that a pH of 7.5- 4,5 (especially &0-9.0) is 65 particularly preferred both for reducing release of acid gas and also for maintaining better levels of other compounds as well, 5,833.864 As shown in FIG. 1. which compares the ratio of hydro-- tolerance of common acid producing bacteria, It is noted that amounts of lime (calcium hydroxide) can be added to gen sulfide to ionized hydrogen sulfide, at a constant temperature, the percentage of ionized hydrogen sulfide small magnesium hydroxide and/or magnesium oxide slurry to increases with an increase in pH, The largest effect is seen in the pH range of 6.0 to 8,0. In particular, at a pH of 6.0. 5 increase the pH and enhance the sIttrry's ability to kill bacteria. It is anticipated that other biocides or hardening 90.1% is hydrogen sulfide. while at a pH of 8.0. only 8.3% agents such as sodium silicate. sodium bi-sulfate, magne- magnesium chloride, phosphates, or other is hydrogen sulfide. Further, at a pH of 8,5. 3% is hydrogen sulfide and at a pH of 9.0. the hydrogen sulfide level drops sium sulfate, materials intended to $apart mechanical strength, may be to less than M, added to further enhance its performance. Therefore. due to the relative insolubility of the agent of 10 in Secondly, as the bacteria is re-cstablished, the alkalinity by the magnesium hydroxide and/or magnesium the invention, conditions can be maintained over time which the amount of hydrogen sulfide which is present or provided oxide neutralizes the acids produced by the bacteria and is reduced and therefore. the odors associated with prevents the rapid re-establishment of bacteria - released the release or presence of hydrogen sulfide are minimized or A magnesium hydroxide and/or` magnesium oxide slurry eliminated. In some embodiments, hydrogen sulfide levels 15 can be prepared by adding, caustic calcined magnesium arc desirably reduced to six parts per million or less the oxide (MgO).preferably in a dry powder four. to water,The magnesia can be obtained from any of the known suppliers Further, it has surprisingly been found that, at pre- ferred pH's of the invention, the undesirable release of iacluding Premier Services Corporation. King of Prussia, ammonia is also minimized. In contrast to hydrogen sulfide of 20 Pa. Premier Services sells magnesia in dry powder form under the trademark MAGM& levels. which decrease. as the pH increases, the release ammonia gas increases with an increase in pH_ Therefore, a When magnesium oxide is added to water it undergoes to magnesium hydrox-ide. The balance is preferred in which the pH level is both (1) high enough to seduce the formation and releast of hydrogen hydration and is converted rate of this reaction can be varied depending upon the sulfide and (2) row enough to prevent the formation and surface area of the MgO, starting water tempemtitre, vessel of ammonia. It has been found that the optimal 25 configuration. and agi�p Either a slowly h release baLmce can be achieved by maintaining a pH in the range of or a fully by g( H)z slurry added to the approximately 7.5 to 9.5. especially 8.0 to 9.0- and most by maintaining a pH of approximately 8.3. contaminated water. A magnesium hydroxide slurry can also be purchased preferably. Moreover, a pH level substantially above 9.0 can be harmful to bacteria which are beneficial to treatment of 3o form any of the known suppliers. including Premier Services which sells a magnesium hydroxide slurry under the trade - waste water and sewerage. Io comparison to other pH mark AQUAMAC4. increasing compounds, magnesium hydroxide has been pHin the desired range In a preferred embodiment of the invention. a spetially hydrated and formulated slurry, marketed by Premier Ser- found to slowly reach and maintain a wilhout substantially overshooting the maximum level, As vices Corporation under the trademarkTHIOGUARDTm. is such; there is less osmotic shock and the helpful organisms 35 added to sewerage or waste water, Without intending to be arc not'destroyed broad by theory. It is believed that this slurry offers a safe. Thcrafine, magnesium hydroxide and/or oxide have been economic alternative reagent for acid neutralization and treatment and has been found to be particularly found to be particularly suitable for the prevention of odor in sewerage and waste water since the alkalinity and 40 water effective in controlling odors later alia by achieving the pH release properties of magnesium hydroxide are such that it is easy and other effects discussed herein, it is believed to neutralize wwnful sulfuric acid It is an off-white slurry composed for the operator to keep PH levels within the preferred range discussed above, without inadvertently raising pH so for predominately of agglomerated magnesium hydroxide par - above the preferred range that the undesirable effects dis- titles and is made from hydrated calcined natural magnesite from sea water. bitterns, or brines. Table 1 cussed above become problematic 45 or precipitated Moreover, it has been found that the low solubility of the below, sets forth a representative cbemical analysis of it on magnesium leads to a time released alkalinity so that the pH a loss free basis. level is more stable and is maintained upstream for a longer TABLE I period of time, As shown in FIG. 2. magnesium hydroxide was able to maintain a pH of above 75 and a level of 5o viscosity, wutipoise Boa-6000, typK-BUY 5000 aqueous sulfides at or below 5 ppm for thirty days. In addition to the benefits of magnesium bydroxide and/or % Solids 55--65 , _, Specific Sattaee Area Typically tom g Chemical AaatyBis BsuL), wt �o oxide discussed above, the use of magnesium hydroxide and/or oxide is preferable for a number of reasons First it MRo 90-99 is noted that magnesiumhydroxide requires no placarding or 55 Coo 03-4 n n �D special handling and presents no chemical hazard to the b SiR,o 0.t-2.0 eaviroument, users, or the public. Second, magnesium ' hydroxide has a higher neutralizing capacity per mole than soda due to its two OH ions. Third. the by-products The component R.203 refers to natural impunities Such as caustic produced by the reaction of magnesium with hydrogen 6o A1203 and Fe.03 which are indigenous to ore bodies Other in to) SiO2, e.g. M9CO3 sulfide tend not to be hazardous as with some by products of Finally, the magnesium require- insolubles besides (err addition and/or CaCO3 may be included, The product THIQ- hydrogen sulf€dereactions. ments are less dependent on sulfide eonceutxation- is believed that two mechanisms are respoasihIe for the GUARD'S is made from natural ore and there are some natnrnl variations in the percentages of various ingredients it r$ec&bness of magnesium hydroxide and/or magnesium 65 as shown inter alia in 'liable L In a preferred embodiment. as shown in FIG. 3, the oxide, First. magnesium hydroxide has a pH of apprnxi- is the magnesium hydroxide or magnesium oxide in the form of a mately i0.5, which. while safe to humans. above 5,933.864 5 slurry is topically applied to a stream of sewerage or waste water. In particular, a storage tank or drum I which holds magnesium hydroxide and/or magnesium oxide pumps the magnesium through a maintenance hole 2 to a sewerage flow 3. Odors from downstream maintenance holes d and carco- sion on crowns and maintenance holes 5 are reduced or eliminated. Addition of sufficient THiOGUARDTm to the sewerage to raise the pit to 9.0-9.5., which takes somewhere between 8.5-100 mg/L dependent upon type of sewerage is sufficient to reduce odor and corrosion problems in sanitary sewers. This occurs because at this pH dissolved hydrogen sulphide gas is at a minimum and does not tend to escape into gaseous phase and contribute to odor and corrosion. For instance addition of IMOGUARDTAI to sewerage at approximately 100 nigh results in an almost instantaneous drop of aqueous sulphides from an initial 16 ppm to less than 1,0 ppm for a period of 4 days and a subsequent rise to between 6-6.5 for a period of 50 days, Apart from its ability to alter sewerage pH to reduce dissolved hydrogen sulphide gas, there is a surface reaction berweenTfROGUARDTm and dissolved hydrogen sulphide. which results in adsorption of the gas onto the solids phase. Mg(03)p+HrS„ L,-Mg(OH)1(HtS),iMg(HS},+20s-+MRSOA Further reaction results in the formation of magnesium hydrosulphide, which can be oxidized by dissolved oxygen to form soluble magnesium sulphate which does not sub- stantially, contribute to odor or corrosion. Due to its limited solubility in water, it is very slow to release hydroxyl ion (OH—) in normalpH range of sewerage compared to other alkalis such as lime and caustic soda, M6(OH)a-4Mg�-+201r- 6 sulated in sodium silicate, In some embodiments, this dry farm may constitute the agent added to sewerage or waste water in accordance with the invention. Ilse acid produced by surface bacteria is neutralized by the sodium silicate, in 5 addition, as the sodium silicate dissolves, the magnesium oxide is exposed, thereby dehydrating the bacteria and neutralizing the hydrogen sulfide, Although the present invention has been described in relation to particular embodiments thereof, many other 10 variations and modifications and other uses will become apparent to those skilled in the art- It is preferred, therefore, that the present invention he limited not by the specific disclosure herein. but only by the appended claims. we claim 1. A method for reducing the formation and release of 15 hydrogen sulfide in municipal sewerage or waste water, comprising the step of.. adding an effective amount of an agent that includes a compound selected from the group consisting of mag- nesium hydroxide and magnesium oxide to said 20 municipal sewerage or waste water, wherein said municipal sewerage or waste water includes at lease one compound which can be reduced to form hydrogen sulfide. 2. The method. as recited in claim 1, wherein said agent 25 is a slurry further including sodium silicate. 1 The method, as recited in claim 1. wherein said agent is a hard alkaline material composite of unhydrated magno- sium oxide encapsulated in sodium silicate. 4, The method, as recited in claim 1,, wherein the com- 30 position is a slurry including: 35 Consequently. MIOGUARDT"t is able to continue to raise the pH downstream of the original point of addition without resulting in excessively high loml pH's. For instance, add- ing it at a rate of 100 mg(l to sewerage is capable of sustaining a pH greater than 84 for 24 hours. 40 Its use to control odor/corrosion problems in sewerage is not limited to just hydrogen sulphide but could encompass other acidic gases/vapors such as sulphur dioxide and sul- phur compounds which contain an ionizable hydrogen ion. such as mereaptans containing the --SH group. 45 It should be realized by those skilled in the art that the magnesium hydroxide and/or magnesium oxide can be added to any other water or liquid solution that is contami- nated by compounds which can be reduced to acid gases. particularly sulfates and mercaptans, 50 The characteristics of the magnesium hydroxide and/or magnesium oxide slurry can be varied to provide the opti- mum pumping eharadetisties and to treat different levels of contamination The properties of the slurry can be varied by any of the 55 known methods including changes in the solids to water ratio, or by the use of polymers to enhance or alter these properties as desired for differing field conditions or equip- ment configurations, a g... increasing or decreasing the water content or by adding in more magnesia powder, 60 It is recommended that the slurry should include at least 30%, preferably at .least 50%. by weight magnesium com- pound in the form of magnesium oxide, magnesium hydrox- ide or a rnil[rure thereof. Magnesium oxide can also be mixed with sodium silicate 65 to produce a slurry which, when dried, yields a hard alkaline material composite of unhydrated magnesium oxide encap- Chmakal Analysis (kiss tree basis) a1 % M80 about 92-9B% CIO about 5-3.5% R201 about 5-1.5% mwlables about 5-10% Viscosity, cPs about SOD-1D,000 density, nwo about 11.E-11, 8 r% soU& by wt % abota 45-55 5. The method. as recited In claim 1, wherein said agent Is substantially continuously, added to said sewerage or waste water. 6. A method of controlling hydrogen sulfide odor associ- ated with municipal sewerage or waste water, comprising the step of: adding an effective amount of an agent that includes a compound selected from the group consisting of mag- nesium hydroxide and magnesium oxide to said municipal sewerage or waste water, wherein said municipal sewerage or waste water includes at least one compound which can be reduced to form hydrogen sulfide. 7. A method of obtaining a minimal level of hydrogen sulfide and of ammonia in municipal waste water or sewerage, comprising the step of: adding an effective amount of an agent that includes a compound selected from the group consisting of mag- nesium hydroxide and magnesium oxide to said municipal sewerage or waste water, wherein said municipal sewerage or waste water includes at least one compound which can be reduced to form hydrogen sulfide. S., The method of claim 1. wherein said agent is added in an amount effective to reduce hydrogen sulfide levels to no more than 6 parts per million. 5.833.864 9, The method of claim 6. wherein said agent is added in an amount effective to reduce hydrogen sulfide levels to no more than 6 parts per trillion. 10, The method of claim 7, wherein said agent is added in an amount effective to reduce hydrogen sulfide levels to no more than 6 parts per million. 11, The method of claim 1. wherein said agent is added in an amount effective to maintain pH of said sewerage or waste water between 7.5 and 9.5, 12. The method of claim 6, wherein said agent is added in an amount effective to maintain pH of said sewerage or waste water between about 7,5 and 9.5, 13, The method of claim 7. wherein said agent is added in ao amount effective to maintain pH of said sewerage or waste water between about T5 and 9,5. 14, The method of claim 1, wherein said agent is added in an amount effective to maintain pH of said sewerage or waste water between about 8,0 and 9.0, M The method of claim 6, wherein said agent is added in an amount effective to maintain pH of said sewerage or waste water between about 8,0 and 9.0, 16, The method of claim 7, wherein said agent is added in an amount effective to maintain pH of said sewerage or waste water between about 8.0 and 9.0, 17. The method of claim 1, wherein said agent is added in an amount effective to maintain pH of about 8,3. 18, The method of claim 6, wherein said agent is added in an amount effective to maintain pH of about 8,3,, 19. The method of claim 7, wherein said agent is added in an amount effective to maintain pH of about 83. 5 20. The method of claim 1, wherein lime is also added. 21, The method of claim 6, wherein lime is also added. 22, The method of claim 7, wherein time is also added. 23, The method of claim 1, wherein said agent is a slurry comprising 30-50% by weight of said magnesium. 24, The method of claim 6, wherein said agent is a slurry 10 comprising 30-50% by weight of said magnesium. 25. The method of claim 7, wherein said agent is a slurry comprising 30-50% by weight of said magnesium. 26, The .method, as recited in claim 1, wherein the composition is a slurry including: Physical and Chemical r5 Properties of THIOGUARDTH Chemical Analysis (Dry Basis), wt % M80 About90-99 C20 About 0,3-4,0 Sip, tabout0.34.0 R30a obool0.I-U Mucosity Boll-600a sat; !=, 96 Solids about 55-65,