WO2015200206A1

WO2015200206A1 - Filter media for treating contaminated water

Info

Publication number: WO2015200206A1
Application number: PCT/US2015/036959
Authority: WO
Inventors: Rupali DATTA; Dibyendu Sarkar; Ramesh ATTINTI
Original assignee: Montclair State University
Priority date: 2014-06-25
Filing date: 2015-06-22
Publication date: 2015-12-30

Abstract

Provided is a filter media for treating contaminated water, comprising processed aluminum water residuals.

Description

FILTER MEDIA FOR TREATING CONTAMINATED WATER

Cross Reference to Related Applications

This application claims priority from U.S. Provisional Patent Application No. 62/016,942 filed on June 25, 2014, the contents of which are hereby expressly incorporated by reference herein.

Field of the Invention

[0001] The instant invention relates a filter media for treating contaminated water, comprising processed aluminum drinking water treatment residuals. The invention also relates to a process of making the filter media as well as to a method of treating contaminated wastewater by using the filter media.

[0002] All documents cited to or relied upon below are expressly incorporated herein by reference.

Statement Regarding Federally Sponsored Research or Development

[0003] This invention was made with Government support under contract number N00024- 09-C-4111 awarded by U.S. Naval Sea Systems Command. The Government has certain rights in the invention.

Background of the Invention

[0004] High urbanization leads to various environmental issues such as polluted urban runoff, the surface stormwater created by urbanization. Increased runoff flushes numerous pollutants into receiving waters. Toxic metals, nutrients, sediments, pathogens, and toxic organic pollutants are examples of pollutants generated in urban areas. Urban runoff is listed as the 3rd largest source of water quality impairments in lakes, and the 2nd most frequent cause of surface water pollution (Viessman et al, 2008). Heavy metals, such as lead (Pb), copper (Cu), zinc (Zn), etc., are of particular concern in urban runoff due to their non-biodegradability, accumulation in environment, and toxicity. Also of concern are nutrients, such as phosphorus (P), that are generated in both residential areas and in urban gardens. Early urban stormwater management focused merely upon reduction of peak flows as rapidly as possible (NJDEP, 2004) and removal of turbidity in the form of total suspended solids (TSS). In contrast, new strategies encourage best management practices (BMPs) to address both quantity and quality issues of urban runoff, which includes removal of metals and nutrients in stormwater. The problems with metals in stormwater are particularly intense in industrial areas, such as shipyards, which generate a lot of metals in close proximity of major surface water bodies.

[0005] Shipyards are heavily industrialized areas where ship building and repair operations, including abrasive grit blasting, metal burning and cutting, and painting operations are routinely conducted. Shipyard activities are conducted outdoors and the pollutants generated are usually not controlled at the source. The pollutants generated in these activities are exposed to rainfall. The subsequent storm water runoff ends up discharging into sensitive marine water bodies. Spray painting-exterior hull, burning, welding and cutting, metal grinding and rolling stock operations are some of the shipyard processes that generate metals and metalloids, such as copper, lead, zinc and chromium, which pose a serious threat to biological organisms in the surrounding marine ecosystem. Welding processes that use stainless steel materials can produce fine chips and fumes that may contain metals known to be carcinogenic to humans (Antonini et al., 2003).

[0006] In order to minimize heavy metal load in urban storm water, a number of measures have been recommended; however, a majority of these measures suffers from practical drawbacks (Kellams et al., 2003). The most commonly used technology for removing metals from storm water is chemical precipitation and sedimentation, which is very expensive and does not lend itself to the variable characteristics of storm water. Also, the application of this method is impractical due to the large volume of storm water that intermittently need treatment.

Emerging technologies such as electrocoagulation and filtration are increasingly being considered for storm water treatment but still remain impractical for full flow treatment (Kellams et al, 2003). Moreover, these processes are not environmentally sustainable, or "green."

[0007] A need exists in the art, therefore, for new sorbent materials for the treatment of contaminated water.

Summary of the Invention

[0008] The present invention is directed to a filter media for treating contaminated water, comprising processed aluminum water treatment residuals. [0009] The present invention is also directed to a filter media comprising aluminum water treatment residuals for treating contaminated water, said filter media made by a process comprising the steps of:

- drying said aluminum water treatment residuals to a moisture content of less than 5%;

- grinding said dried aluminum water treatment residuals;

- sieving said ground aluminum water treatment residuals to a mean particle size of from 0.5 to 2.0 mm; and

- adding a coagulant to said sieved aluminum water treatment residuals.

[0010] The invention is further directed to a method of treating contaminated water, comprising the step of passing said contaminated water through a filter media comprising processed aluminum water treatment residuals.

Brief Description of the Figures

[0011] Figure 1 is a schematic diagram of the pilot treatment set up of an embodiment of the invention.

Detailed Description of the Invention

[0012] It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for the purpose of clarity, many other elements found in typical pharmaceutical compositions and methods of stabilization. Those of ordinary skill in the art will recognize that other elements and/or steps are desirable and/or required in implementing the present invention. However, because such elements and steps are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements and steps is not provided herein. The disclosure herein is directed to all such variations and modifications to such elements and methods known to those skilled in the art. Furthermore, the embodiments identified and illustrated herein are for exemplary purposes only, and are not meant to be exclusive or limited in their description of the present invention. [0013] Heavy metal persistence in stormwater poses a major challenge for local governments as they strive to comply with regional water quality standards. The invention, in one embodiment, is a "green" sorbent that is derived primarily from an industrial byproduct, namely drinking-water treatment residuals (WTRs) as a novel, efficient and highly economical solution for removal of heavy metals and P from stormwater. The sorbent, also interchangeably referred to herein as "filter media", was developed to be useful not only for urban stormwater, but also for industrial stormwater (e.g., shipyards), as well as industrial process water and secondary treatment for wastewater. The sorbent is capable of removing heavy metals, phosphorus, and also organics and turbidity when used alone or as an additive to commonly used filter media, such as sand, activated carbon, or mulch.

[0014] WTRs are primarily amorphous masses of iron (Fe) or aluminum (Al) hydroxides (referred to as Fe-WTRs (use of Fe salt) or Al-WTRs (Al salt)), respectively, that also contain sediment and humic substances removed from the raw water, as well as polyelectrolytes added to raw water, such as activated carbon and polymers (O'Connor et al., 2001). More than 2 Mg of WTRs are generated from the drinking water treatment facilities in the U.S. daily (Prakash and Sengupta, 2003). Disposal of WTRs is currently regulated at the state level, not at the federal level; thus, different regulations exist for WTR disposal at different states. Nation-wide, WTRs are specifically exempt from the 40 CFR Part 503 land disposal regulations for biosolids, as they are considered non-hazardous materials (USEPA, 1996). Thus, the WTRs from which the filter media of the invention is derived can be safely utilized without having to meet metal and oxyanion limitations of the Part 503 regulation. WTRs are considered non-hazardous wastes by USEPA, thus, a Toxicity Characteristic Leaching Protocol (TCLP) test is adequate prior to their beneficial re-use in the technology of the invention. Published TCLP data on WTRs suggest no human health risk associated with contaminant leaching in aqueous solutions (O'Connor et al., 2001, Makris et al, 2006a). The TCLP values for toxic metals, such as Pb, Cd, Zn, Cu, Cr, Ag, Mn, etc., for a representative Al-WTR used as source materials in an embodiment of the invention are well below the hazardous waste toxicity characteristic criteria as defined in Title 40 of the Code of Federal Regulations (CFR), Part 261.24 (Table 1): Table 1

Toxicity characteristic values of several metals and metalloids measured in Al- and Fe- WTRs using the TCLP extraction method (reproduced from Makris et al., 2006a)

BDL (Below Detection Limits): ICP-AES instrument detection limits.

[0015] The filter media of the invention can be made from industrial waste generated in US drinking water treatment plants via alum treatment, called Aluminum Water Treatment residuals (Al-WTR). Raw Al-WTR can be subjected to USEPA's TCLP (Toxicity Characteristic Leaching Protocol) to determine if it can be classified as non-hazardous waste. If it is found to be non-hazardous (primary criterion), then the Al-WTR is dried to reduce themoisture content of the Al-WTR.. Dried WTR is ground and sieved using various sieves of various pore sizes, to generate fractions. To the sorbent, a coagulant such as, for example, chitosan, can be added to help enhance its metal chelating properties.

A representative composition of the filter media of the invention is provided below, wherein the numbers shown are the mean of three replicates ± one standard deviation:

Examples

[0016] The disclosure is further illustrated by the following examples, which are not to be construed as limiting this disclosure in scope or spirit to the specific procedures herein described. It is to be understood that the examples are provided to illustrate certain embodiments and that no limitation to the scope of the disclosure is intended thereby. It is to be further understood that resort may be had to various other embodiments, modifications, and equivalents thereof which may suggest themselves to those skilled in the art without departing from the spirit of the present disclosure and/or scope of the appended claims.

Example 1 Preparation of Filter Media

[0017] The filter media of the invention was made from Al-WTR. The process of making the filter media included the following steps:

-Raw Al-WTR was subjected to USEPA's TCLP (Toxicity Characteristic Leaching Protocol) to determine if it can be classified as non-hazardous waste. -If it is classified as non-hazardous (primary criterion), then the Al-WTR was dried at room temperature by spreading the residuals out and air drying for 2 weeks.

-Moisture content of dried Al-WTR was brought down to less than 5% by checking the WTRs at regular intervals for moisture content. The WTR was dried for several weeks until the requisite moisture content was reached.

-Dried WTR was ground and sieved using various sieves of various pore sizes, to generate fractions of sizes <0.5 mm, 0.5 - 2.0 mm and >2 mm. The 0.5 -2.0 mm fraction of processed Al-WTR was used to make the sorbent because of its reactive capacity without compromising water flow.

-To the sorbent, 0.1% C-573 coagulant (chitosan-derived, hence, "green" obtained from Cytec Industries Inc.) was added to help enhance its metal chelating properties.

[0018] The filter media so made had the properties as shown in Table 2 below, where all data were mean of 10 samples from both sources and wherein values can vary 20% from the mean either way and still be considered acceptable.

Table 2

Chemical composition of filter media of the invention

Example 2 Testing Shipyard Stormwater Using a Flow Reactor System

[0019] Stormwater samples were collected from a shipyard in Mississippi. The stormwater composition is shown in Table 3. Experiments were conducted under continuous, saturated flow conditions using polycarbonate columns packed with various combinations of the sorbent of Example 1 with sand. Several trials were performed. After passing the storm water through the column, effluents were collected, and metal ions concentrations in the effluents were analyzed by Inductively-coupled Plasma Mass Spectrometry (ICP-MS).

Table 3

Concentration of metals in shipyard stormwater

[0020] The pH and turbidity values of the shipyard stormwater were 6.55 and 205.2, respectively. Concentrations of metals (total and dissolved), e.g., Ag, Al, As, Cd, Cr, Cu, Fe, Ni, Pb and Zn in Huntington Ingalls storm water are provided in Table 3. Complete removal (more than 99%, the effluent concentrations are below 10 ppb) of metals were achieved (Table 4).

Table 4

Concentration of total metals in Huntington Ingalls stormwater after column elution

Design of the pilot reactor

[0021] Based on the results of the laboratory column studies, a pilot unit was designed to treat the shipyard stormwater. The reactor primarily consisted of two units. In the first unit, storm water was pumped from the container using peristaltic pump. The second unit acted as a filtration unit. This unit removed the metals and other contaminants from the stormwater.

Various ratios of the filter media of Example 1 and sand were used to pack the reactor to treat the metals in stormwater. The rate of metal removal, pH and turbidity in influent and effluent samples were monitored. Once the certain conditions were established, a scaled-up reactor was prepared and shipped to the shipyard where shipyard stormwater was passed through the reactor in real time; influent and effluent samples were monitored. Results are shown in Tables 5 and 6.

Table 5

Turbidity Values of storm water samples

Table 6

Concentration of metals in storm water before (Influent) and after treatment (Effluent)

[0022] The results show that the concentrations of metal ions in the stormwater after treatment were well within the USEPA disposal limits.

[0023] In addition to shipyard stormwater, boat pump-out wastewater was also treated using the filter media of Example 1. Table 7 shows the values of turbidity and pH of the influent and effluent pump-out wastewater. Table 7

Turbidity and pH values of pump-out stormwater influent and effluent samples

Example 3

Treatment of Industrial Process Water using a Sequential Batch Reactor

[0024] Company X is one of world's largest providers of aircraft engine and accessories maintenance, repair and overhaul (MRO) services. It generates a huge amount of industrial process water effluent that is extremely contaminated with metals, and are typically

characterized by high pH, and very high turbidity. A pilot system was designed based on bench tests with process water samples generated in the Town Y facility of Company X. The primary effluent waste stream was contaminated process water from the on-site metal washing facilities. The Town Y facility produces -1000 gallons of process water per week, and currently no treatment systems were in place to handle this waste stream. Representative effluent samples were collected from Town Y's washroom waste stream for preliminary bench tests. A prototype system was fabricated and tested using the effluent samples. Following this bench-scale study, available data was compiled and analyzed to determine the feasibility of scaling up the prototype to a full-scale system for on-site demonstration.

[0025] A two-stage sequencing batch reactor (SBR) consisting, in one embodiment, of a reaction vessel (for removal of soluble contaminants by the filter media of Example 1) and a clarification vessel where suspended materials are removed by addition of a coagulant was set up. The process water had a high pH, high buffer capacity, and contained high concentrations of detergents, which further complicated the treatment process. In addition, the turbidity was very high, and the water contained high levels of various heavy metals. The concentration of metals in the untreated process water and other parameters are shown in Table 8. Table 8

Untreated Process Water

[0026] Prior to reaction with the filter media of Example 1 , the pH of incoming effluent was adjusted to ~7.0 using industrial grade muriatic acid. To remove the large amounts of surfactants from wastewater, the filter media of Example 1 was fortified with activated carbon. Both powdered and granular activated carbon were equally effective in removing surfactants. The results (summarized in Table 9) show that, with the exception of Al and Fe (which are not considered contaminants), the SBR system lowered the concentrations of all other metals present in the industrial process water to levels below instrumental detection limit (IDL). Further, the turbidity values decreased with increasing dilution of process water.

Table 9

Turbidity and concentration of metal ions in treated process water

BDL (Below Detection Limits): ICP-AES instrument detection limits. Pilot Unit Demonstration at Company X facility in Town Y

[0027] Following the success of the bench scale experiments a scaled up pilot SBR unit was designed and fabricated for on-site testing under operational conditions. The pilot unit was deployed at Company X's overhaul facility in Town Y to test if it could be a viable treatment for process water generated at the metal parts washing facility located on-site.

[0028] As shown in Figure 1 , prior to treatment, the industrial process water was diluted by a factor of three using tap water (1 part process water: 3 parts tap water). The diluted process water was transferred into the reaction vessel and the pH was neutralized (pH ~7.0) with muriatic acid (1 : 1). Then, the mixed sorbent (the filter media of Example 1 and granulated activated carbon) was added to the process water (900 g/gallon treated) to remove the metals, turbidity, and surfactants. The solution mixture was stirred for 30 min (200 rpm) and allowed to settle for 45 min. The supernatant was transferred into the clarifying vessel and the flocculating agent was added (1 mL of 10% C-573 solution/ gallon treated).

[0029] After adding the C-573 flocculating agent, the solution was rapidly mixed (100 rpm) for 1 min, followed by a slow mixing (30 rpm) for 30 min. After the coagulation/flocculation process, the sample was allowed to settle for 45 min. The treated effluent was split in two streams: one third (1/3) of the treated water was discharged, while the remaining two thirds (2/3) was recycled to the head of treatment system for process water dilution.

[0030] The treated process water using the filter media of Example 1 was much clearer than the untreated process water. The ICP-MS results of the treated process water (Table 10) show that except for Al and Fe, all the studied metals (Ag, As, Cd, Cr, Cu, Ni, Pb and Zn) in the contaminated water were reduced to negligible concentrations. These results demonstrate the high capacity of SBR system with the filter media of Example 1 in removing toxic metals, turbidity, and surfactants from industrial process water. This, coupled with the cost effective and "green" quality of this technology make the filter media of Example 1 an ideal solution for treatment of this type of industrial waste streams. Table 10

Concentration of metal ions ^ /ml) in process water before and after treatment

[0031] The invention is further described by the following numbered paragraphs:

1. A filter media for treating contaminated water, comprising processed aluminum water treatment residuals.

2. The filter media according to paragraph 1, wherein said processed aluminum water treatment residuals have a moisture content of less than 5%.

3. The filter media according to paragraph 1, wherein said processed aluminum water treatment residuals have a mean particle size of between 0.5 and 2.0 mm.

4. The filter media according to paragraph 1, further comprising a coagulant.

5. The filter media according to paragraph 4, wherein said coagulant comprises chitosan or a derivative thereof or combinations thereof.

6. The filter media according to paragraph 1, further comprising sand.

7. A filter media comprising aluminum water treatment residuals for treating contaminated water, said filter media made by a process comprising the steps of:

- grinding said dried aluminum water treatment residuals;

- adding a coagulant to said sieved aluminum water treatment residuals.

8. The filter media according to paragraph 7, wherein said coagulant comprises chitosan or a derivative thereof or combinations thereof.

9. The filter media according to paragraph 7, further comprising the step of adding sand to said coagulated aluminum water treatment residuals. 10. The filter media according to paragraph 9, wherein the ratio of sand to coagulated aluminum water treatment residuals is 5 : 1.

11. A method of treating contaminated water, comprising the step of passing said

contaminated water through a filter media comprising processed aluminum water treatment residuals.

12. The method according to paragraph 11 , wherein said processed aluminum water treatment residuals have a moisture content of less than 5%.

13. The method according to paragraph 11, wherein said processed aluminum water treatment residuals have a mean particle size of between 0.5 and 2.0 mm.

14. The method according to paragraph 11, wherein said filter media further comprises a coagulant.

15. The method according to paragraph 14, wherein said coagulant comprises chitosan or a derivative thereof or combinations thereof.

16. The method according to paragraph 11, wherein said filter media further comprises sand.

References

Antonini JM, Lewis AB, Roberts JR, Whaley DA (2003). Pulmonary effects of welding fumes: review of worker and experimental animal studies. Am J Ind Med 43:350-360.

Kellems BL, Randall Johnson PE, Sanchez F (2003) Design of emerging technologies for control and removal of stormwater pollutants. Presented at Water, World & Environmental Resources Congress, Philadelphia.

Makris KC, Harris WG, O'Connor GA, Obreza TA (2004) Phosphorus immobilizationnin micropores of drinking water treatment residuals: Implications for long-term stability. Environ. Sci. Technol. 38: 6590-6596. Makris KC, Sarkar D, Datta R (2006a) Evaluating a drinking-water waste by-product as a novel sorbent for arsenic. Chemosphere 64: 730-741.

Makris KC, Sarkar D, Datta R (2006b) Aluminum-based drinking water treatment residuals: A novel sorbent for perchlorate removal. Env. Pollut. 140: 9-13.

O'Connor GA, Elliott HA, Lu P (2001) Characterizing water treatment residuals phosphorus retention. Soil Crop Sci Soc Fl Proc 61 : 67-73.

O'Connor GA, Elliott HA, Lu P (2001) Characterizing water treatment residual phosphorus retention. Soil Crop Sci. Soc. FL Proc. 61 : 67-73.

Prakash O, Sengupta AK (2003) Selective coagulant recovery from water treatment plant residues using Donnan membrane process. Environ. Sci. Technol. 34: 4408-4474.

U.S. Environmental Protection Agency (1996) Management of water treatment residuals.

EPA/625/R-95/008. Office of research and development, Washington, DC.

Viessman, W., Hammer, M.J., Perez, E.M., Chadik, P.A. (2008) Water Supply and Pollution Control. 8th Edition. Prentice Hall.

* * *

It is to be understood that the invention is not limited to the particular embodiments of the invention described above, as variations of the particular embodiments may be made and still fall within the scope of the appended claims.

Claims

2. The filter media according to claim 1 , wherein said processed aluminum water treatment residuals have a moisture content of less than 5%.

3. The filter media according to claim 1, wherein said processed aluminum water treatment residuals have a mean particle size of between 0.5 and 2.0 mm.

4. The filter media according to claim 1, further comprising a coagulant.

5. The filter media according to claim 4, wherein said coagulant comprises chitosan or a derivative thereof or combinations thereof.

6. The filter media according to claim 1, further comprising sand.

- grinding said dried aluminum water treatment residuals;

- adding a coagulant to said sieved aluminum water treatment residuals.

8. The filter media according to claim 7, wherein said coagulant comprises chitosan or a derivative thereof or combinations thereof.

9. The filter media according to claim 7, further comprising the step of adding sand to said coagulated aluminum water treatment residuals.

10. The filter media according to claim 9, wherein the ratio of sand to coagulated aluminum water treatment residuals is 5 : 1.

11. A method of treating contaminated water, comprising the step of passing said contaminated water through a filter media comprising processed aluminum water treatment residuals.

12. The method according to claim 11, wherein said processed aluminum water treatment residuals have a moisture content of less than 5%.

13. The method according to claim 11, wherein said processed aluminum water treatment residuals have a mean particle size of between 0.5 and 2.0 mm.

14. The method according to claim 11, wherein said filter media further comprises a coagulant.

15. The method according to claim 14, wherein said coagulant comprises chitosan or a derivative thereof or combinations thereof.

16. The method according to claim 11, wherein said filter media further comprises sand.