WO2012148417A1

WO2012148417A1 - Improving performance of wastewater lagoons

Info

Publication number: WO2012148417A1
Application number: PCT/US2011/034510
Authority: WO
Inventors: Kurt A. Reichold; Keith W. KENNEDY; Scott VASSEUR; Stephen Lyon
Original assignee: Diversey, Inc.
Priority date: 2011-04-29
Filing date: 2011-04-29
Publication date: 2012-11-01

Abstract

Methods of increasing dissolved oxygen concentration and chlorophyll concentration in a lagoon are described herein. Also disclosed are methods of improving the performance of a wastewater lagoon by applying to the surface of the lagoon a composition comprising at least one surfactant and at least one enzyme.

Description

IMPROVING PERFORMANCE OF WASTEWATER LAGOONS

BACKGROUND

[0001] Lagoon systems include one or more pond-like bodies of water or basins designed to receive, hold, and treat wastewater for a period of time. While in the lagoon, wastewater may receive treatment through a combination of physical, biological, and chemical processes. Some of the treatment occurs naturally, with the aid of aerobic bacteria to break down pollutants and photosynthetic algae to provide oxygen to the bacteria. Some systems are designed to also use aeration devices that increase the amount of oxygen in the wastewater, which may make treatment more efficient.

[0002] Aerators may require significant energy to operate. Wastewater treatment lagoons can also require significant amounts of flocculants such as ferric chloride. Odor control is also a concern. Compositions and methods for improving the performance of wastewater treatment lagoons may significantly reduce the costs associated with their operation.

SUMMARY

[0003] In one aspect, the disclosure provides a method of improving the performance of a wastewater lagoon, comprising applying to the surface of the lagoon a composition comprising: a) at least one amphoteric surfactant; and b) at least one enzyme.

[0004] In another aspect, the disclosure provides a method of increasing dissolved oxygen concentration in a lagoon, comprising applying to the surface of the lagoon a composition comprising: a) at least one amphoteric surfactant; and b) at least one enzyme.

[0005] In another aspect, the disclosure provides a method of increasing algae content in a wastewater lagoon, comprising applying to the surface of the lagoon a composition comprising: a) at least one amphoteric surfactant; and b) at least one enzyme.

[0006] Other aspects and embodiments are encompassed by the disclosure and will become apparent in light of the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 depicts breakdown of pollutants in a wastewater lagoon by bacteria, using oxygen produced by photosynthetic algae, in addition to oxygen entering the lagoon by diffusion.

[0008] FIG. 2 depicts an exemplary diagram of the time for a composition or product to diffuse throughout a lagoon when fed in through a single point. [0009] FIG. 3 depicts an exemplary diagram of the time for a composition or product to diffuse throughout the lagoon when applied with a high pressure spray wand to the edges of the lagoon.

[0010] FIG. 4 depicts an exemplary diagram of an application time for applying a composition or product to the surface of a lagoon using methods described herein.

[0011] FIG. 5 depicts ferric chloride consumption at a lagoon required to maintain a final effluent phosphorus concentration of 0.8 ppm, before and after treatment with ReNew A.

[0012] FIG. 6 depicts five-day average measurements of dissolved oxygen in a non- aerated municipal wastewater lagoon at a depth of one foot, before and after application of ReNew A to the surface of a lagoon.

[0013] FIG. 7 depicts five-day average measurements of dissolved oxygen in a non- aerated municipal wastewater lagoon at a depth of two foot, before and after application of ReNew A to the surface of a lagoon.

[0014] FIG. 8 depicts five-day average measurements of dissolved oxygen in an aerated municipal wastewater lagoon at a depth of one foot, before and after application of ReNew A to the surface of a lagoon.

[0015] FIG. 9 depicts: A) the flow of water through a wastewater lagoon; B) a graph of the change in dissolved oxygen from influent to effluent.

[0016] FIG. 10 depicts measurements of chlorophyll A concentrations at a depth of one foot before and after application of ReNew A to the surface of a lagoon.

[0017] FIG. 11 depicts a Pourbaix diagram for sulfur, with indication of a possible mechanism for odor reduction after treatment with ReNew A.

DETAILED DESCRIPTION

[0018] Described herein are methods to improve the performance of a lagoon, such as a wastewater treatment lagoon. The methods include applying to the surface of the lagoon a composition comprising at least one amphoteric surfactant and at least one enzyme. Also disclosed are methods of increasing dissolved oxygen concentration in a wastewater lagoon, and methods of increasing algae content in a wastewater lagoon. Described herein are methods of monitoring the performance of a wastewater treatment lagoon, comprising measuring chlorophyll concentration and optionally at least one of pH, temperature, dissolved oxygen, conductivity, oxidation reduction potential, chemical oxygen demand, sulfide concentration, ammonia concentration and turbidity. Definitions

[0019] As used herein, the term "apply" or "applying," when used in the context of applying a composition to the surface of a wastewater lagoon, refers to the application of a composition to at least a substantial portion of the surface of the lagoon. Suitably, applying a composition to the surface of a lagoon may be such that at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, or at least about 99% of the surface of the lagoon is contacted with or covered by a composition. Applying includes methods, such as, for example, spraying a composition on to the surface of the lagoon.

[0020] As used herein, the term "improve" or "improving," when used in the context of the performance of a lagoon such as a wastewater treatment lagoon, refers to a measurable or noticeable benefit in a property of the lagoon. Depending on the nature of the particular property (e.g., algae content, odor), the improved property may be a relative increase (e.g., algae content) or a relative decrease (e.g., odor) of the property. Some non-limiting improvements include a reduction of odor, a reduction in power consumption, a reduction in effluent water pollution, an increase in dissolved oxygen concentration, or an increase in algae content.

[0021] As used herein, "lagoon" refers to bodies of water such as industrial lagoons (e.g., dairies, food processing plants, rendering plants, etc.), agricultural concentrated animal feeding operations ("CAFOs"), commercial retention or fire protection ponds (e.g., for shopping centers, department stores, etc.), residential run-off ponds, municipal treatment lagoons (e.g., residential sewage lagoons), and other similar bodies of water.

[0022] It is specifically understood that any numerical value recited herein includes all values from the lower value to the upper value, i.e., all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application. For example, if a range is stated as 1% to 50%, it is intended that values such as 2% to 40%, 10% to 30%, or 1% to 3%, etc., are expressly enumerated in this specification. These are only examples of what is specifically intended.

Compositions

[0023] Compositions that are suitable for use in the methods described herein, for example, in application to the surface of a lagoon may comprise at least one surfactant and at least one enzyme. [0024] The surfactant may include, without limitation, a non-ionic surfactant, a cationic surfactant, an anionic surfactant or an amphoteric surfactant, or combinations thereof.

[0025] Examples of nonionic surfactants include, but are not limited to, amides, alkanolamides, amine oxides, block polymers, alkoxylated primary and secondary alcohols, alkoxylated alkylphenols, alkoxylated fatty esters, sorbitan derivatives, glycerol esters, propoxylated and alkoxylated fatty acids, alcohols, and alkyl phenols, glycol esters, and polymeric polysaccharides.

[0026] Nonionic surfactants are conventionally produced by condensing ethylene oxide with a hydrocarbon having a reactive hydrogen atom, e.g., a hydroxyl, carboxylic acid group, primary and secondary amino, or primary or secondary amido group, in the presence of an acidic or basic catalyst. Nonionic surfactants may have the general formula

RA(CH₂CH₂0)_nH wherein R represents the hydrophobic moiety, A represents the group carrying the reactive hydrogen atom and n represents the average number of ethylene oxide moieties. R may be a primary or a secondary, straight or slightly branched, aliphatic alcohol having from about 8 to about 24 carbon atoms. A more complete disclosure of nonionic surfactants can be found in U.S. Pat. No. 4,111,855, Barrat, et al., issued September 5, 1978, and U.S. Pat. No. 4,865,773, Kim et al., issued September 12, 1989, which are hereby fully incorporated by reference.

[0027] Other nonionic surfactants useful in the composition include ethoxylated alcohols or ethoxylated alkyl phenols of the formula R(OC₂H₄)_nOH, wherein R is an aliphatic hydrocarbon radical containing from about 8 to about 18 carbon atoms or an alkyl phenyl radical in which the alkyl group contains from about 8 to about 15 carbon atoms, and n is from about 2 to about 14. Examples of such surfactants are listed in U.S. Pat. No. 3,717,630, Booth, issued Feb. 20, 1973, U.S. Pat. No. 3,332,880, Kessler et al., issued July 25, 1967, and U.S. Pat. No. 4,284,435, Fox, issued August 18, 1981, which are hereby fully incorporated by reference.

[0028] Moreover, other nonionic surfactants include the condensation products of alkyl phenols having an alkyl group containing from about 8 to about 15 carbon atoms in either a straight chain or branched chain configuration with ethylene oxide, said ethylene oxide being present in an amount from about 2 to about 14 moles of ethylene oxide per mole of alkyl phenol. The alkyl substituent in such compounds can be derived, for example, from polymerized propylene, diisobutylene, and the like. Examples of compounds of this type include nonyl phenol condensed with about 9 moles of ethylene oxide per mole of nonyl phenol, dodecyl phenol condensed with about 8 moles of ethylene oxide per mole of phenol, and the commercially available T-DET® 9.5 marketed by Harcros Chemicals Incorporated.

[0029] Other useful nonionic surfactants are the condensation products of aliphatic alcohols with from about 2 to about 14 moles of ethylene oxide. The alkyl chain of the aliphatic alcohol can either be straight or branched, primary or secondary, and may contain from about 8 to about 18 carbon atoms. Examples of such ethoxylated alcohols include secondary alcohol nonionic surfactants such as ENS-70, the condensation product of myristyl alcohol condensed with about 9 moles of ethylene oxide per mole of alcohol, and the condensation product of about 7 moles of ethylene oxide with coconut alcohol (a mixture of fatty alcohols with alkyl chains varying in length from 10 to 14 carbon atoms). Examples of commercially available nonionic surfactants in this type include: Tergitol™ 15-S-7 or 15-S-9 marketed by Union Carbide Corporation; Neodol™ 45-9, Neodol™ 23-6.5, Neodol™ 45-7 and Neodol™ 45-4 marketed by Shell Chemical Company; Kyro EOB marketed by The Procter & Gamble Company; and Berol® 260 and Berol® 266 marketed by Akzo Nobel. Other suitable non-ionic surfactants include Neodol™ ethoxylates, commercially available from Shell Chemicals (Houston, TX) and Tergitol™ surfactants, commercially available from Dow (Midland, MI). A mixture of nonionic surfactants may also be used.

[0030] Examples of anionic surfactants include, but are not limited to, sulfosuccinates and derivatives, sulfates of ethoxylated alcohols, sulfates of alcohols, sulfonates and sulfonic acid derivatives, sulfates and sulfonates of alkoxylated alkylphenols, phosphate esters, and polymeric surfactants. Suitably, anionic surfactants may include, but are not limited to, alkyl sulfate, ether sulfate, alkyl benzene sulfonate, alpha olefin sulfonate, diphenyloxide disulfonate, alkyl naphthalene sulfonate, sulfosuccinate, sulfosuccinamate, naphthalene- formaldehyde condensate, isethionate, N-methyl taurate, phosphate ester, and ether carboxylate.

[0031] Amphoteric surfactants may include betaines and betaine derivatives. Amphoteric surfactants may also include, but are not limited to, amphoteric imadazoline derivatives and fatty amine and fatty amine ethoxylate derivatives. Amphoteric imadazoline derivatives may include, but are limited to, amphodiacetates, amphoacetates, amphocarboxylates,

amphopropionate, amphodipropionate, and hydroxypropyl sulfonate. Fatty amine and fatty amine ethoxylate derivatives may include, but are not limited to, betaines, alkyl betaine, sultaine, dihydroxyethyl glycinate, alkyl amidopropyl betaine, and aminopropionate. [0032] Cationic surfactants may include amine surfactants, those containing non- quaternary nitrogen, those containing quaternary nitrogen bases, those containing non- nitrogenous bases and combinations thereof. Such surfactants are disclosed in U.S. Pat. No. 3,457,109, Peist, issued July 22, 1969, U.S. Pat. No. 3,222,201, Boyle, issued Dec. 7, 1965 and U.S. Pat. No. 3,222,213, Clark, issued December 7, 1965, which are hereby fully incorporated by reference.

[0033] One category of cationic surfactants may include quaternary ammonium compounds with the general formula RXYZ N⁺A^", wherein R is an aliphatic or cycloaliphatic group having from 8 to 20 carbon atoms and X, Y and Z are members selected from the group consisting of alkyl, hydroxylated alkyl, phenyl and benzyl. A^" is a water soluble anion that may include, but is not limited to, a halogen, methosulfate, ethosulfate, sulfate and bisulfate. The R group may be bonded to the quaternary group through hetero atoms or atom groups such as -0-, -COO-, -CON-, -N-, and -S-. Examples of such compounds include, but are not limited to, trimethyl-hexadecyl-ammonium sulfate, diethyl-octadecyl-phenyl- ammonium sulfate, dimethyl-dodecyl-benzyl-ammonium chloride, octadecylamino-ethyl- trimethyl-ammonium bisulfate, stearylamido-ethyl-trimethyl-ammonium methosulfate, dodecyloxy-methyl-trimethyl-ammonium chloride, cocoalkylcarboxyethyl-di-(hydroxyethyl)- methyl- ammonium methosulfate, and combinations thereof.

[0034] Another category of cationic surfactants may be of the di-long chain quaternary ammonium type having the general formula XYRRiN⁺A^~, wherein X and Y chains may contain an average of from about 12 to about 22 carbon atoms and R and Ri may be hydrogen or CI to C4 alkyl or hydroxyalkyl groups. Although X and Y may contain long chain alkyl groups, X and Y may also contain hydroxy groups or may contain heteroatoms or other linkages, such as double or triple carbon-carbon bonds, and ester, amide, or ether linkages, as long as each chain falls within the above carbon atom ranges.

[0035] An additional category of cationic surfactant may include the bis(ethoxylated) ammonium quaternary compounds having the general formula:

R I Θ

H-(OCH₂CH₂)-— N— (CH₂CH₂0)— H A

Ri

wherein R is methyl, ethyl or propyl group, Ri is an alkyl group having from 8 to 18 carbon atoms, an alkenyl group having 8 to 18 carbon atoms or mixtures thereof, x is a number from 1 to 40, y is a number from 1 to 40, wherein x + y is between 10 to 60, and A is a water soluble anion. Examples of such compounds include, but are not limited to, alkyl bis(ethoxy) methyl ammonium methyl sulfate (15 moles EO), stearyl methyl bis(ethoxy) ammonium chloride (12 moles EO), stearyl ethyl bis(ethoxy) ammonium ethyl sulfate (15 moles EO), tallow methyl bis(ethoxy) ammonium methyl sulfate (15 moles EO), tallow ethyl bis(ethoxy) ammonium ethyl sulfate (15 moles EO), hydrogenated tallow methyl bis(ethoxy) ammonium chloride (15 moles EO), coco methyl bis(ethoxy) ammonium methyl sulfate (20 moles EO), and combinations thereof.

[0036] Other cationic surfactants may include sulfonium, phosphonium, and mono- or tri- long chain quaternary ammonium materials and those described in U.S. Pat. No. 4,259,217, Murphy, issued March 31, 1981, U.S. Pat. No. 4,222,905, Cockrell, September, 16, 1980, U.S. Pat. No. 4,260,529, Letton, issued April 7, 1981, U.S. Pat. No. 4,228,042, Letton, issued October 14, 1980, and U.S. Pat. No. 4,228,044, Cushman, issued October 14, 1980, each of which is fully incorporated herein by reference.

[0037] Additional cationic surfactants may include ditallowalkyldimethyl (or diethyl or dihydroxyethyl) ammonium chloride, ditallowalkyldimethylammonium methyl sulfate, dihexadecylalkyl (CI 6) dimethyl (or diethyl, or dihydroxyethyl) ammonium chloride, dioctodecylalkyl (CI 8) dimethylammonium chloride, dieicosylalkyl (C20)

dimethylammonium chloride, methyl (1) tallowalkyl amido ethyl (2) tallowalkyl

imidazolinium methyl sulfate (commercially available as Varisoft 475 from Ashland

Chemical Company), or mixtures of those surfactants.

[0038] Additional surfactants that may be used in the compositions and methods described herein may be found in U.S. Patent Nos. 6,054,139, 6,547,063, and 7,572,933, each of which is incorporated herein by reference in their entireties.

[0039] Suitably, the surfactant of the composition may be amphoteric. The surfactant of the composition may be a zwitterion. The composition may comprise two or more

surfactants. The composition may comprise at least about 1%, at least about 2%, at least about 5%, or at least about 7% of surfactant by weight. The composition may also comprise less than about 95%, less than about 15%, less than about 10%, less than about 8% of surfactant by weight. The composition may comprise about 1 to about 95 wt%, about 2 to about 15 wt%, about 5 to about 15 wt%, about 5 to about 10 wt%, or about 7 to about 8 wt% of surfactant.

[0040] The enzyme of the composition can comprise at least one of a protease, a lipase, a hydrolase, a cellulase, an amylase, or any combination thereof. The composition can comprise one or more enzyme or protein that fall within other classes of enzymes and proteins in addition to the at least one protease, lipase, hydrolase, cellulose, amylase or combination thereof. The composition may comprise an amylase and a protease. The composition may comprise less than about 10 wt%, less than about 5 wt%, less than about 2 wt%, less than about 1 wt%, or less than about 0.5 wt% of enzyme. There are many materials derived from plant, animal, and microbial sources that have been known to those skilled in the art to be rich sources of enzymes. These source materials may be used with full, partial, or no purification of enzymes to obtain enzymes for use in the composition. For example, the enzyme may be exogenously produced from a recombinant or wild-type organism. The enzyme may be purified. The enzyme may be a fermentation product.

[0041] The balance of the composition can comprise other standard components such as, for example, solvents, carriers, diluents, buffers, preservatives, fragrances, and enzyme stabilizers such as propylene glycol and borates.

[0042] Suitably, the composition is commercially available as ReNew A and also as Odor-Out (Diversey, Sturtevant, WI).

[0043] The composition may suitably be applied to a lagoon at a concentration sufficient to elicit a desired effect, such as a reduction of odor, a reduction in power consumption, a reduction in effluent water pollution, an increase in dissolved oxygen concentration, or an increase in algae content. Suitably, the composition may be applied to a concentration of about 1 to 25 mg/L, e.g., from about 6 to 12 mg/L. In embodiments, the concentration of the composition that is applied to the lagoon can be based on the weight percentage of the surfactant or the enzyme, or both, in the composition. One of skill in the art will be able to determine amounts and concentrations based on the particular application, the desired effect, and the existing condition of the lagoon.

[0044] Without being limited by theory, compositions such as those described herein may improve the performance of wastewater lagoons by increasing concentrations of dissolved oxygen in the lagoon. Such oxygen may then be available to bacteria that use oxygen to break down pollutants (see Figure 1). For example, the oxygen may be used as a substrate by enzymes, such as metalloenzymes, that react with organic molecules to initiate their breakdown.

[0045] Compositions such as those described herein may influence (i.e., induce or modulate) algae in lagoons to produce more oxygen. Such activity may be used in methods to analyze the performance of a lagoon, for example, by measuring dissolved oxygen in the lagoon, or by measuring the concentration of chlorophyll in the lagoon. Such measurements may be made directly using probes attached to a data gathering vessel, or by obtaining water samples using such a vessel and returning them to land for further analysis.

Methods of application

[0046] A typical method of administering (e.g., contacting or applying) a composition to wastewater treatment lagoons includes, for example, feeding a composition into a lagoon via the headworks. Such methods, however, typically require additional time to allow the composition to diffuse throughout the lagoon from the injection point (see Figure 2 for an exemplary embodiment). These increased or extended times may be due to the hydraulic resident times associated with quiescent lagoons. Such times may delay the time it takes for a lagoon operator to notice an effect, such as a decrease in odor. Further, such single point- of-application methods may impair research efforts due to the slow and steady increase in product concentration as the product diffuses from a single injection point, which may make it difficult to correlate changes in lagoon performance to the treatment chemistry. In a lagoon with aerators, diffusers, or mixers, the hydraulic residence time can be as short as 1 day; in an unstirred, still, or otherwise undisturbed lagoon that is being operated below design capacity, the residence time can be as long as 90 days.

[0047] Another method of applying a composition to a wastewater lagoon includes, for example, spraying a composition onto the edges of a lagoon using, for example, a high- pressure spray wand (e.g., a power washer). As illustrated in Figure 3, a composition applied in such a way may gradually diffuse to the center of the lagoon, with concentric circles illustrating how long it may take to reach target concentration in an exemplary embodiment. While this approach is faster than simple injection at the headworks, it remains slow and still presents difficulties for research efforts due to the changing concentration of the composition over time. Additionally, this technique may present safety concerns for a lagoon operator and the surrounding community, as wastewater lagoons may contain quantities of pathogenic microorganisms that could be aerosolized by a high pressure spraying process.

[0048] A suitable method of application for the compositions described herein comprises spraying a composition on to the surface of the lagoon such that at least about at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, or at least about 99% of the surface of the lagoon is coated with the composition. Thus, embodiments provide for application of the composition over a substantial amount of the surface area of the lagoon. Applying includes methods, such as, for example, spraying a composition on to the surface of the lagoon. A composition may be sprayed on to the surface of a lagoon using a vessel, such as an inflatable raft, equipped with pumps and a spray boom, which can be used to apply a composition to the lagoon surface at an appropriate

concentration. A vessel in this configuration can be navigated around the lagoon by any suitable method such as, for example, automated or manual remote control (e.g., comprising known and available GPS and/or radio frequency technologies), or manual/physical navigation, e.g., pulling across the water by hand, by another manned or unmanned watercraft, or by one or more vehicles on shore. In either case, the composition may be rapidly and evenly applied and distributed uniformly (see Figure 4 for an exemplary embodiment). This fast and uniform treatment may provide a near- immediate odor improvement benefit, and may allow the results of analytical tests to be more clearly attributable to the application of the composition.

Methods of analysis

[0049] The disclosure provides methods of improving the performance of a wastewater treatment lagoon. As described above, application of a composition comprising at least one surfactant and at least one enzyme may increase amounts of dissolved oxygen in the lagoon, for example, by increasing algae levels or by aerating the lagoon during the application.

Accordingly, in some embodiments the performance of a wastewater lagoon may be monitored, for example, by measuring chlorophyll concentrations. Additional measurements may include determinations of pH, temperature, dissolved oxygen, conductivity, oxidation reduction potential (ORP), chemical oxygen demand (COD), sulfide concentration, ammonia concentration and turbidity. Depending on the specific parameter to be determined, these measurements may be made using an automated, or at least partially automated, system for gathering and analyzing characteristic data for the lagoon. For example, a data gathering device (e.g., a boat, a raft, a remote controlled vessel, a platform, etc.) can be fitted with relevant electronic probes connected to a meter or meters, which can be secured to the device. The meters may optionally protected from the elements by confining them to water-tight containers, or the entire data gathering device can be covered (e.g., using a tarp). The device can be remotely or manually controlled such that it gathers data from most of or an entire lagoon. The lagoon can generally be divided into a number of areas or coordinates for which data is to be gathered. After the data has been gathered, the data can be compressed, processed, and analyzed. Suitably, parameters that may be determined in this manner include pH, ORP, conductivity, dissolved oxygen and temperature. [0050] Embodiments provide for measurements that may be made by obtaining water samples from a lagoon and subsequently analyzing them away from the lagoon, such as in a laboratory. Water samples can be collected using a portable automatic water sampler, such as a portable sampler from Teledyne Isco. These battery-powered samplers can collect up to 24 discrete water samples, and can be programmed to collect the water from a single point at various time intervals, such as every hour. A similar setup can be used to collect water samples from various points on a rectilinear grid, to determine a profile of water chemistry as a function of position and depth. A water sampler may be secured to a vessel (e.g., a boat, a raft, a remote controlled vessel, a platform, etc.), which can be remotely or manually controlled to gather water samples from the lagoon. Suitably, parameters that may be determined in this manner include chlorophyll concentrations, COD, sulfide and ammonia concentrations, and turbidity. pH

[0051] High or low effluent pH problems can occur in lagoons for different reasons. Low effluent pH (<7.0) may be due to either organic overloading and low oxygen conditions, or due to nitrification when the lagoon alkalinity (buffer capacity) is low. High effluent pH may be due to excessive algae growth. Algae consume inorganic carbon for growth and the pH may increase as carbon dioxide, bicarbonate and carbonate levels decrease. Accordingly, the pH may be monitored, and treatment of the lagoon may be modified in response to the pH measurements.

[0052] The pH can be measured using a standard pH probe, which may be commercially available from a number of suppliers such as Hach (e.g., PHC101 IntelliCAL™ Rugged Gel Filled pH electrode). Probes can be affixed to the side of a data gathering device at an appropriate depth and connected to a meter, such as a Hach HQ40d dual-input meter, to record measurements at given time points.

Temperature

[0053] Temperature levels may affect bacterial and algal growth, as well as dissolved oxygen levels and other parameters. For research purposes, temperature may be monitored to provide certainty that changes in these parameters are attributable to changes in lagoon chemistry. Temperature can be monitored using a standard temperature probe, such as those available from Hach. Chlorophyll Concentrations

[0054] Algae levels may be determined based on measurements of chlorophyll a, which is a pigment essential for oxygenic photosynthesis. Chlorophyll-a concentrations may be measured, for example, using method # 102000 H as described in Standard Methods for the Examination of Water and Wastewater, pages 10-18 to 10-20, incorporated herein by reference, in which the absorbance is measured at wavelengths of 664 and 750 nm. These measurements may be made away from the lagoon, e.g., in a laboratory, using collected water samples as described above.

Dissolved Oxygen

[0055] As the sun rises and sets, the photosynthesis process that generates oxygen speeds up and slows down, and will completely stop at night. This daily, or diurnal cycle, is a normal part of lagoon performance, and is a useful way to evaluate performance. The activity of algae may change over the course of a day, with the peak performance, or maximum dissolved oxygen, often occurring in the evenings. The oxygen produced during the day is continuously being consumed by bacteria, and once the photosynthetic oxygen is depleted, the dissolved oxygen in the water will eventually decrease to zero at night. The peak height is a useful measure of how much dissolved oxygen algae are producing. Higher levels of dissolved oxygen may result in a higher level of lagoon performance (more rapid reduction in organic pollutants) and reduced odor.

[0056] Dissolved oxygen may be measured using a dissolved oxygen probe, such as those available from Hach (e.g., a Hach LDO101 IntelliCAL™ Rugged Dissolved Oxygen Probe). Such a probe can be affixed to the side of a data gathering device at an appropriate depth and connected to a meter, such as a Hach HQ40d dual-input meter, to record measurements at given time points.

Oxidation Reduction Potential

[0057] ORP is the potential (voltage) at which oxidation occurs at the anode (positive) and reduction occurs at the cathode (negative) of an electrochemical cell. More oxidizing conditions may result in greater breakdown of pollutants in a lagoon as well as oxidation of noxious gases such as hydrogen sulfide, which in turn can lead to lower odor. The ORP scale can range from about - 500 mV to + 500 mV in lagoon systems, with higher (more positive) numbers indicating healthier, relatively odor free conditions.

[0058] ORP can be measured using an ORP probe, such as a Hach IntelliCAL™ ORP Rugged Gel-Filled Probe. Such a probe can be affixed to the side of a data gathering device at an appropriate depth and connected to a meter, such as a Hach HQ40d dual-input meter, to record measurements at given time points.

Conductivity

[0059] Conductivity is measure of the ability of a solution to carry an electrical current, and accordingly is an indicated of dissolved ionic compounds (e.g., sodium chloride, carbonates and sulfates. Conductivity can be measured, for example, to provide an indicate of lagoon dilution due to rain water on the lagoon surface or storm water incursion in the collection system that feeds the lagoon. For example, if measurements indicate a reduction in Chemical Oxygen Demand, and a corresponding reduction in conductivity is not observed, the reduction may be due to a biological process. If both values are reduced, the changes may be due to simple dilution.

[0060] Conductivity can be measured using a conductivity probe, such as a Hach

CDC401 IntelliCAL™ ORP Rugged Conductivity. Such a probe can be affixed to the side of a data gathering device at an appropriate depth and connected to a meter, such as a Hach HQ40d dual-input meter, to record measurements at given time points.

Chemical oxygen demand

[0061] The chemical oxygen demand (COD) test may be used to indirectly measure the amount of organic compounds in a lagoon, making it a useful measure of water quality. It is often expressed in milligrams per liter (mg/L), which indicates the mass of oxygen consumed per liter of solution.

[0062] The basis for the COD test is that nearly all organic compounds can be fully oxidized to carbon dioxide with a strong oxidizing agent under acidic conditions. The amount of oxygen required to oxidize an organic compound to carbon dioxide, ammonia, and water is given by the following formula:

[0063] Oxidizing agents such as eerie sulfate, potassium iodate or potassium dichromate and the like may be used to determine COD. COD may be measured, for example, using Hach TNTPlus™ reagents. These measurements may be made away from the lagoon, e.g., in a laboratory, using collected water samples as described above. Other lagoon parameters

Odor reduction

[0064] Odor is a concern for municipal wastewater lagoons. Application of compositions described herein to wastewater lagoons using methods described herein may reduce odor. Figure 5 illustrates a possible mechanism for odor reduction, in the form of a Pourbaix diagram for sulfur. The region illustrated in gray shows the pH and ORP that will produce hydrogen sulfide, a noxious gas associated with the smell of rotten eggs. For waters having a pH and ORP in this range, hydrogen sulfide will form, or once formed, will remain stable. Increasing the ORP of the water using methods described herein may result in a shift out of this region of the diagram, rendering hydrogen sulfide less stable and lowering its

concentration.

Flocculant addition

[0065] Flocculants or coagulants are often added to municipal wastewater lagoons to facilitate removal of phosphorus. Suitable flocculants include ferric chloride and aluminum sulfate. Application of compositions described herein to wastewater lagoons may increase algae content. Phosphorus uptake by algae may result in decreased requirements for flocculants in wastewater lagoons.

[0066] The following non-limiting Examples are intended to be purely illustrative, and show specific experiments that were carried out in accordance with the disclosure.

EXAMPLES

Example 1. Dissolved oxygen and reduction potential measurements

[0067] Dissolved oxygen concentrations and oxidation-reduction potentials were measured in a non-aerated wastewater lagoon in Francesville, Indiana. The measurements were taken in one of the two lagoon cells, which holds approximately 6 million gallons of water with a residence time of about 90 days. The measurements were taken using Hach LDO101 IntelliCAL™ Rugged Dissolved Oxygen Probes secured to an inflatable raft at depths of 1 foot and 2 feet and connected to a Hach HQ40d dual-input meter. The raft was stationed at a single point in the lagoon approximately 100 feet from the shore, and data were collected for five days before and five days after addition of 10 mg/L ReNew A (Diversey, Sturtevant, WI), which had been sprayed evenly onto to the surface of the lagoon using an inflatable raft equipped with a 25-foot spray boom having 14 nozzles, a 40-gallon chemical reservoir, and two chemical pumps. The raft was towed back and forth across the surface of the lagoon using ropes such that the entire surface of the lagoon was coated with the composition.

[0068] Data are illustrated in Table 1. Dissolved oxygen increased at both 1 and 2 feet after ReNew A application, and oxidation reduction potentials are more positive after ReNew A application.

[0069] Graphs depicting five-day averages over the full diurnal cycle are illustrated in Figures 6 and 7, with measurements at a 1 foot depth shown in Figure 6 and measurements at a 2 foot depth shown in Figure 7. As illustrated in the graphs, the maximum dissolved oxygen occurs between 5:00 p.m. and 6:00 p.m., and dissolved oxygen decreases to zero during the overnight hours. This is consistent with increased production of oxygen by photosynthetic algae. These higher levels of dissolved oxygen may result in a higher level of lagoon performance (more rapid reduction in organic pollutants) and reduced odor.

Table 1. Five-day average values before and after ReNew application in Francesville,

IN

Example 2. Dissolved oxygen and reduction potential measurements

[0070] Dissolved oxygen concentrations and oxidation-reduction potentials were measured in a non-aerated wastewater lagoon in Antwerp, Ohio. The measurements were taken in one of the primary and secondary lagoon cells, which holds approximately 2 million gallons of water with a residence time of about 10 days each. The measurements were taken using a Hach LDO101 IntelliCAL™ Rugged Dissolved Oxygen Probe secured to an inflatable raft, at a depth of 1 foot. Data were collected for five days before and five days after addition of 10 mg/L ReNew A, which was sprayed onto the edges of the lagoon using a power sprayer.

[0071] Data are illustrated in Table 2. The dissolved oxygen levels prior to ReNew A application were very low, indicating that the lagoon was low-functioning. Although the ORP did not move as much as the data presented in Table 1, the DO doubled in the first five days after the ReNew A addition. [0072] A graph depicting five-day averages over the full diurnal cycle are illustrated in Figure 8. As illustrated in the graphs, the maximum dissolved oxygen occurs between 5:00 p.m. and 6:00 p.m., and dissolved oxygen decreases to zero during the overnight hours. This is consistent with increased production of oxygen by photosynthetic algae. These higher levels of dissolved oxygen may result in a higher level of lagoon performance (more rapid reduction in organic pollutants) and reduced odor.

Table 2. Five-day average values before and after ReNew application in Antwerp, OH

[0073] A graph depicting changes in dissolved oxygen concentration from influent to effluent is illustrated in Figure 9. An increase in oxygen is observed following ReNew A treatment.

Example 3. Chlorophyll concentration

[0074] Chlorophyll concentrations were determined in water samples collected from a depth of one foot in an aerated wastewater stabilization system in Winamac, Indiana. The measurements were taken in one of the three lagoon cells, which holds approximately 4 million gallons of water with a residence time of about 10 days each (30 days total). Water samples were collected every two hours for a period before and after the application of ReNew A to a concentration of 10 mg/L, and chlorophyll A levels were measured using method # 102000 H as described in Standard Methods for the Examination of Water and Wastewater, pages 10-18 to 10-20 (incorporated herein by reference). Algae samples were filtered through a glass fiber filter. The filter was then ground up in a test tube containing glass beads and an extraction solution (90% acetone and 10% water saturated with magnesium carbonate). The tube was then placed in a centrifuge and spun to separate the solution containing the chlorophyll from the fragments of the glass fiber filter. An aliquot of 3 ml of the solution was placed in a 1 cm cuvette and then placed in a

spectrophotometer. Optical density (OD) readings were taken at wavelengths of 664 and 750 nm. After OD readings were taken, 0.10 ml of 0.1 N HC1 as added to the cuvette. After gentle mixing, another set of OD readings are taken at 665 and 750 nm. The concentration of chlorophyll-α was then determined using a formula that takes into account the volume of the extract, the volume of the sample, the length of the light path and the optical density readings.

[0075] As illustrated in Figure 10, the chlorophyll concentration increased rapidly, suggesting that increased algae levels were responsible for the observed increase in dissolved oxygen. This experiment was repeated at Antwerp, Ohio, with similar results.

Example 4. Ferric chloride consumption

[0076] Prior to ReNew A treatment, the wastewater stabilization system in Winamac, Indiana was supplied with ferric chloride to produce a final effluent phosphorus concentration of 0.8 ppm. Following regular application of ReNew A, ferric chloride concentrations were lowered as illustrated in Figure 11. Such reduction did not adversely affect final effluent phosphorus concentration, resulting in significant cost savings.

[0077] All patents, publications and references cited herein are hereby fully incorporated by reference. In case of conflict between the present disclosure and incorporated patents, publications and references, the present disclosure should control.

Claims

1. A method of improving the performance of a wastewater treatment lagoon, comprising applying to the surface of the lagoon a composition comprising:

a) at least one amphoteric surfactant; and

b) at least one enzyme.

2. The method of claim 1, wherein at least one amphoteric surfactant is a zwitterion.

3.. The method of claim 1, wherein the composition comprises two amphoteric surfactants at about 5-15 % by weight of the composition.

4. The method of claim 1, wherein at least one enzyme comprises an amylase, a protease, or a combination thereof.

5. The method of claim 1, wherein the composition is applied to at least 50% of the lagoon surface.

6. The method of claim 1, wherein the composition is applied to at least 75% of the lagoon surface.

7. The method of claim 1, wherein the composition is applied to at least 90% of the lagoon surface.

8. The method of claim 1, wherein the composition is applied to the surface by spraying the composition on to the surface.

9. A method of increasing dissolved oxygen concentration in a lagoon, comprising applying to the surface of the lagoon a composition comprising:

a) at least one amphoteric surfactant; and

b) at least one enzyme.

10. The method of claim 9, wherein at least one amphoteric surfactant is a zwitterion.

11. The method of claim 9, wherein the composition comprises two amphoteric surfactants at about 5-15 % by weight of the composition.

12. The method of claim 9, wherein at least one enzyme comprises an amylase, a protease, or a combination thereof.

13. The method of claim 9, wherein the composition is applied to at least 50% of the lagoon surface.

14. The method of claim 9, wherein the composition is applied to at least 75% of the lagoon surface.

15. The method of claim 9, wherein the composition is applied to at least 90% of the lagoon surface.

16. The method of claim 9, wherein the composition is applied to the surface by spraying the composition on to the surface.

17. A method of increasing algae content in a wastewater lagoon, comprising applying to the surface of the lagoon a composition comprising:

a) at least one amphoteric surfactant; and

b) at least one enzyme.

18. The method of claim 17, wherein at least one amphoteric surfactant is a zwitterion.

19. The method of claim 17, wherein the composition comprises two amphoteric surfactants at about 5-15 % by weight of the composition.

20. The method of claim 17, wherein at least one enzyme comprises an amylase, a protease, or a combination thereof.

21. The method of claim 17, wherein the composition is applied to at least 50% of the lagoon surface.

22. The method of claim 17, wherein the composition is applied to at least 75% of the lagoon surface.

23. The method of claim 17, wherein the composition is applied to at least 90% of the lagoon surface.

24. The method of claim 17, wherein the composition is applied to the surface by spraying the composition on to the surface.