Treatment reference

Constituent Removal Cheat Sheet

A practical guide to selecting treatment media for common wastewater constituents.

Published: 12/15/2025 by Jason Chesley

Summary

A cheat sheet for selecting a media type for constituent removal at the tertiary or polishing stage. Bookmark this page so you have access to the most current information as things do change.

Constituent	Media Types	Citations
1,2,3-trichloropropane (C₃H₅Cl₃)	Granular Activated Carbon	[16]
2,4-dichlorophenoxyacetic acid (C₈H₆Cl₂O₃)	Granular Activated Carbon	[16]
2-methylisoborneol (C₁₁H₂₀O)	Granular Activated Carbon	[16]
Algae Cells	Anthracite, Pumice, Sand	[4], [28], [30]
Ammonium Ions (NH₄⁺)	Ion Exchange Resin, MicroZ, Zeolite	[19], [24], [32]
Antimony Ions (Sb³⁺/Sb⁵⁺)	Activated Alumina, ArsenXnp, Bayoxide E33, Bone Char, FerrIX A33, Greensand, Ion Exchange Resin, Katalox Light, Manganese Dioxide, Zeolite	[1], [5], [6], [8], [11], [18], [19], [20], [23], [32]
Arsenate Ions (AsO₄³⁻)	Activated Alumina, ArsenXnp, Bayoxide E33, Bone Char, FerrIX A33, Greensand, Ion Exchange Resin, Katalox Light, Manganese Dioxide, Zeolite	[1], [5], [6], [8], [11], [18], [19], [20], [23], [32]
Arsenic Ions (As³⁺/As⁵⁺)	Activated Alumina, ArsenXnp, Bayoxide E33, Bone Char, FerrIX A33, Greensand, Katalox Light, KDF55, KDF85, Manganese Dioxide	[1], [5], [6], [8], [11], [18], [20], [21], [23]
Arsenite Ions (AsO₃³⁻)	Greensand, Katalox Light, Manganese Dioxide	[18], [20], [23]
Atrazine (C₈H₁₄ClN₅)	Granular Activated Carbon	[16]
Azo Dyes	Granular Activated Carbon, Ion Exchange Resin	[16], [19]
Barium Ions (Ba²⁺)	Bone Char, Ion Exchange Resin	[8], [19]
Benzene (C₆H₆)	Granular Activated Carbon, OrganoClay	[16], [26]
Bicarbonates (HCO₃⁻)	Ion Exchange Resin	[19]
Biofilms	Activated Glass Filtration Media	[3]
Boron Ions (B³⁺)	Ion Exchange Resin	[19]
Bromoacetic Acid (CH₂BrCOOH)	Granular Activated Carbon	[16]
Bromodichloromethane (CHBrCl₂)	Granular Activated Carbon	[16]
Bromoform (CHBr₃)	Granular Activated Carbon	[16]
Cadmium Ions (Cd²⁺)	Bayoxide E33, Bone Char, FerrIX A33, Ion Exchange Resin, KDF85, OrganoClay, Zeolite	[6], [8], [11], [19], [21], [26], [32]
Calcium Ions (Ca²⁺)	Ion Exchange Resin	[19]
Carbamazepine (C₁₅H₁₂N₂O)	Granular Activated Carbon	[16]
Carbon Dioxide (CO₂)	Calcite	[9]
Chloral Hydrate (C₂H₃Cl₃O₂)	Granular Activated Carbon	[16]
Chlorides (Cl⁻)	Ion Exchange Resin	[19]
Chloroform (CHCl₃)	Granular Activated Carbon	[16]
Chloramines	Centaur Carbon	[10]
Chlorine (Cl₂)	Granular Activated Carbon	[16]
Chromium Ions (Cr³⁺/Cr⁶⁺)	Activated Alumina, Ion Exchange Resin, KDF55, KDF85, OrganoClay, Zeolite	[1], [19], [21], [26], [32]
Clay	Activated Glass Filtration Media, Filter-Ag, Garnet, MicroZ, Pumice, Sand	[3], [12], [14], [24], [28], [30]
Cobalt Ions (Co²⁺)	Ion Exchange Resin, Zeolite	[19], [32]
Coliform Bacteria, E. coli, Fecal/Total Coliforms	Anthracite, Sand, Zeolite	[4], [30], [32]
Color-Causing Compounds	Bone Char, Granular Activated Carbon, Ion Exchange Resin	[8], [16], [19]
Colloids	Activated Glass Filtration Media, Filter-Ag, Garnet, Katalox Light, Pumice, Sand	[3], [12], [14], [20], [28], [30]
Copper Ions (Cu²⁺)	Bayoxide E33, Bone Char, FerrIX A33, Ion Exchange Resin, Katalox Light, KDF85, MicroZ, OrganoClay, Zeolite	[6], [8], [11], [19], [20], [21], [24], [26], [32]
Cryptosporidium Oocysts	Activated Glass Filtration Media, Garnet, MicroZ	[3], [14], [24]
Detritus	Anthracite, Garnet, Pumice	[4], [14], [28]
Diatoms	Activated Glass Filtration Media, Sand	[3], [30]
Dibromoacetic Acid (CHBr₂COOH)	Granular Activated Carbon	[16]
Dibromochloromethane (CHBr₂Cl)	Granular Activated Carbon	[16]
Dichloramine (NHCl₂)	Centaur Carbon	[10]
Dichloroacetic Acid (CHCl₂COOH)	Granular Activated Carbon	[16]
Diclofenac (C₁₄H₁₁Cl₂NO₂)	Granular Activated Carbon	[16]
Disinfection Byproducts	Granular Activated Carbon	[16]
Ethylbenzene (C₈H₁₀)	Granular Activated Carbon, OrganoClay	[16], [26]
Fats	OrganoClay, Pecan Shell, Walnut Shell	[26], [27], [31]
Ferric Iron (Fe³⁺)	Activated Glass Filtration Media, Centaur Carbon, Filter-Ag, Greensand, Katalox Light, KDF85, Magnetite, Manganese Dioxide, MicroZ, Sand, Zeolite	[3], [10], [12], [18], [19], [20], [21], [22], [23], [24], [30], [32]
Ferrous Iron (Fe²⁺)	Ion Exchange Resin	[19]
Fluoride Ions (F⁻)	Activated Alumina, Bone Char	[1], [8]
Fulvic Acids	Anthracite, Bone Char, Graphite, Granular Activated Carbon	[4], [8], [15], [16]
Geosmin (C₁₂H₂₂O)	Granular Activated Carbon	[16]
Giardia Cysts	Activated Glass Filtration Media, Garnet, MicroZ	[3], [14], [24]
Glyphosate (C₃H₈NO₅P)	Granular Activated Carbon	[16]
Hardness	Ion Exchange Resin	[19]
Humic Acids & Substances	Activated Alumina, Anthracite, Bone Char, Graphite, Granular Activated Carbon, Ion Exchange Resin	[1], [4], [8], [15], [16], [19]
Hydrocarbons	Granular Activated Carbon, OrganoClay, Pecan Shell, Walnut Shell	[16], [26], [27], [31]
Hydrogen Ions (H⁺) / Acidity	Calcite	[9]
Hydrogen Sulfide (H₂S)	Centaur Carbon, Filox, Greensand, Katalox Light, KDF85, Manganese Dioxide, MTM, Pyrolox	[10], [13], [18], [20], [21], [23], [25], [29]
Ibuprofen (C₁₃H₁₈O₂)	Granular Activated Carbon	[16]
Larger Clusters (Coliform, E. Coli, Sediment)	Anthracite	[4]
Lead Ions (Pb²⁺)	Activated Alumina, Bayoxide E33, Bone Char, FerrIX A33, Ion Exchange Resin, Katalox Light, KDF55, KDF85, MicroZ, OrganoClay, Zeolite	[1], [6], [8], [11], [19], [20], [21], [24], [26], [32]
Legionella pneumophila	Diatomaceous Earth	[2]
Magnesium Ions (Mg²⁺)	Ion Exchange Resin	[19]
Manganese Ions (Mn²⁺)	Birm, Centaur Carbon, Filox, Greensand, Ion Exchange Resin, Katalox Light, KDF85, Magnetite, Manganese Dioxide, MicroZ, MTM, Pyrolox, Zeolite	[7], [10], [13], [18], [19], [20], [21], [22], [23], [24], [25], [29], [32]
Manganese Precipitates (Mn²⁺)	Activated Glass Filtration Media, Anthracite, Calcite, Filter-Ag, Garnet, Katalox Light, Magnetite, MicroZ, Sand	[3], [4], [9], [12], [14], [20], [22], [24], [30]
Mercury Ions (Hg²⁺)	Bone Char, Granular Activated Carbon, Ion Exchange Resin, KDF55, KDF85, Zeolite	[8], [16], [19], [21], [32]
Methyl Tert-Butyl Ether (C₅H₁₂O)	Granular Activated Carbon, OrganoClay	[16], [26]
Microplastics	Activated Glass Filtration Media	[3]
Monochloramine (NH₂Cl)	Centaur Carbon	[10]
Nickel Ions (Ni²⁺)	Ion Exchange Resin, KDF55, KDF85, Zeolite	[19], [21], [32]
Nitrate Ions (NO₃⁻)	Ion Exchange Resin	[19]
Nitrite Ions (NO₂⁻)	Ion Exchange Resin	[19]
Oils	OrganoClay, Pecan Shell, Walnut Shell	[26], [27], [31]
Organic Compounds	Granular Activated Carbon, Graphite	[15], [16]
Perchlorate Ions (ClO₄⁻)	Ion Exchange Resin	[19]
Perchloroethylene (C₂Cl₄)	Granular Activated Carbon	[16]
Perfluorooctanesulfonic Acid (C₈HF₁₇O₃S), Perfluorooctanoic Acid (C₈HF₁₅O₂), PFAS (Per- and Polyfluoroalkyl Substances), Forever Chemicals	Granular Activated Carbon, OrganoClay	[16], [26]
Petroleum Hydrocarbons	OrganoClay, Pecan Shell, Walnut Shell	[26], [27], [31]
Phenolic Compounds	Granular Activated Carbon, Zeolite	[16], [32]
Phosphate Ions (PO₄³⁻)	Activated Alumina	[1]
Polycyclic Aromatic Hydrocarbons	Granular Activated Carbon, OrganoClay, Pecan Shell, Walnut Shell	[16], [26], [27], [31]
Potassium Ions (K⁺)	Ion Exchange Resin, Zeolite	[19], [32]
Pseudomonas Aeruginosa	Diatomaceous Earth	[34]
Radium Ions (Ra²⁺), Radium-226 (²²⁶Ra), Radium-228 (²²⁸Ra)	Bayoxide E33, Bone Char, Greensand, Ion Exchange Resin, Katalox Light, Manganese Dioxide	[6], [8], [18], [19], [20], [23]
Residual Floc Particles	Sand	[30]
Selenate Ions (SeO₄²⁻)	Activated Alumina, ArsenXnp	[1], [5]
Selenite Ions (SeO₃²⁻)	Activated Alumina, ArsenXnp	[1], [5]
Selenium Ions (Se⁴⁺/Se⁶⁺)	Activated Alumina, ArsenXnp, Ion Exchange Resin	[1], [5], [19]
Silica Ions (SiO₃²⁻)	Activated Alumina, Ion Exchange Resin	[1], [19]
Silt	Activated Glass Filtration Media, Filter-Ag, Garnet, MicroZ, Pumice, Sand	[3], [12], [14], [24], [28], [30]
Simazine (C₇H₁₂ClN₅)	Granular Activated Carbon	[16]
Sodium Ions (Na⁺)	Ion Exchange Resin, Zeolite	[19], [32]
Strontium Ions (Sr²⁺)	Bone Char, Ion Exchange Resin	[8], [19]
Sulfamethoxazole (C₁₀H₁₁N₃O₃S)	Granular Activated Carbon	[16]
Sulfates (SO₄²⁻)	Ion Exchange Resin	[19]
Suspended Solids to 3 Microns	Activated Glass Filtration Media, Katalox Light	[3], [20]
Suspended Solids to 5 Microns	Activated Glass Filtration Media, Garnet, Katalox Light, MicroZ	[3], [14], [20], [24]
Suspended Solids to 10 Microns	Activated Glass Filtration Media, Garnet, Katalox Light, Magnetite, MicroZ, Pecan Shell, Walnut Shell	[3], [14], [20], [22], [24], [27], [31]
Suspended Solids to 15 Microns	Activated Glass Filtration Media, Garnet, Katalox Light, Magnetite, MicroZ, Pumice	[3], [14], [20], [22], [24], [28]
Suspended Solids to 20 Microns	Activated Glass Filtration Media, Filter-Ag, Garnet, Graphite, Katalox Light, Magnetite, MicroZ, Sand	[3], [12], [14], [15], [20], [22], [24], [30]
Suspended Solids to 40 Microns	Activated Glass Filtration Media, Anthracite, Filter-Ag, Garnet, Katalox Light, Magnetite, MicroZ	[3], [4], [12], [14], [20], [22], [24]
Taste-Impairing Compounds	Bone Char, Granular Activated Carbon	[8], [16]
Tetrachloroethylene (C₂Cl₄)	Granular Activated Carbon	[16]
Toluene (C₇H₈)	Granular Activated Carbon, OrganoClay	[16], [26]
Trichloroacetic Acid (CCl₃COOH)	Granular Activated Carbon	[16]
Trichloroethylene (C₂HCl₃)	Granular Activated Carbon	[16]
Trichloramine (NCl₃)	Centaur Carbon	[10]
Turbidity	See suspended solids
Uranium Ions (UO₂²⁺)	Bayoxide E33, Bone Char, FerrIX A33, Ion Exchange Resin	[6], [8], [11], [19]
Vanadium Ions (V⁵⁺)	Zeolite	[32]
Volatile Organic Compounds (VOCs)	Granular Activated Carbon, Graphite	[15], [16]
Xylenes (C₈H₁₀)	Granular Activated Carbon, OrganoClay	[16], [26]
Zinc Ions (Zn²⁺)	Ion Exchange Resin, Katalox Light, MicroZ, OrganoClay, Zeolite	[19], [20], [24], [26], [32]

Glossary

Use these definitions as a quick reference when comparing treatment media and constituent-removal strategies.

Term	Definition
Activated	Refers to a process where materials like carbon or alumina are treated (e.g., via heat or chemicals) to create a highly porous structure with increased surface area for adsorption; common in media like granular activated carbon (GAC) for removing organics, chlorine, and odors in water treatment.
Activated Alumina	Porous, high-surface-area material made by treating aluminum ore (bauxite) to make it adsorptive; used for removing fluoride, arsenic, selenium, silica, and humic acids; requires regeneration with alum, acid, or caustic; effective in dedicated vessels for anion-specific polishing.
Activated Glass Filtration Media (AGFM)	Manufactured from specific glass types and processed to create a fine, antimicrobial filtration medium; replaces sand in filters for superior removal of particulates down to ~3 microns; eco-friendly (recycled glass) with lower backwash needs; used in pressure filters for polishing.
Anthracite	Crushed and screened anthracite coal used as a lightweight, porous filter medium; primarily for mechanical removal of larger suspended solids and turbidity in multimedia beds; often the top layer due to low density; durable with high void space for better flow rates in surface water treatment.
ArsenXnp	Hybrid ion exchange resin infused with iron oxide nanoparticles; specialized for selective removal of arsenic (arsenite/arsenate), selenium, and antimony; high capacity and regenerable; used in fixed-bed systems for groundwater polishing where arsenic exceeds EPA limits.
Bayoxide E33	Granular ferric oxide (α-FeOOH) adsorptive medium; designed for arsenic removal (up to 99%) with long life (6-36 months); also targets certain heavy metals like lead and uranium; non-regenerable (disposable); ideal for centralized treatment in arsenic-contaminated wells.
Birm	Manufactured medium of plastic or aluminum silicate coated with manganese oxide; acts as a catalytic oxidant for iron and manganese reduction; requires no regeneration (only backwashing); effective at pH >6.8 with dissolved oxygen; used in iron-rich groundwater polishing.
Bone Char	Carbonized animal bones (about 10% carbon content) used as a selective anion exchanger; effective for fluoride, arsenic, and certain heavy metals removal, plus decolorization; regenerable but often disposable; common in endemic fluoride areas or for taste/color improvement in drinking water.
Calcite	Crushed calcium carbonate (CaCO₃, often marble or limestone); dissolves to neutralize acidic water, raise pH, and reduce corrosivity; also filters precipitated iron/manganese; self-limiting (dissolves only as needed); used in upflow vessels for final pH stabilization.
Centaur Carbon	Catalytic activated carbon modified for enhanced redox reactions; removes chloramines, hydrogen sulfide, iron, and manganese; requires dissolved oxygen and EBCT of 5+ minutes; used post-disinfection for taste/odor and metal polishing in municipal systems.
Clay	Very fine mineral particles (typically <0.002 mm in size) derived from rock weathering, often suspended in water; contributes to turbidity and can clog filters; removed by mechanical filtration media like sand or garnet.
Colloids	Tiny particles (0.001-1 micron) that remain suspended in water without settling, including organic and inorganic matter; they scatter light, increasing turbidity, and are harder to remove than larger solids; often targeted by coagulants before filtration.
Constituents	The various substances or components present in water, including dissolved ions, suspended solids, organics, and contaminants; in treatment, refers to what media target for removal to improve water quality (e.g., arsenic, chlorine, or ammonia).
Corosex	Magnesium oxide (MgO) medium, often crushed; used for aggressive pH correction in very acidic waters; dissolves to raise pH and add magnesium; can over-correct if not blended (e.g., with calcite); applied in neutralizing filters for corrosion control. Removed from options out of caution.
Detritus	Dead or decaying organic matter (e.g., plant leaves, animal remains, fecal material, or microbial debris) that can be suspended or settled in water; provides nutrients upon decomposition but contributes to oxygen demand and turbidity; filtered out by media like anthracite or pumice in tertiary stages.
FerrIX A33	Granular ferric oxide-based adsorptive medium; specialized for arsenic, certain heavy metals, and uranium removal; high capacity and long-lasting; non-regenerable; used in pressure vessels for groundwater treatment in contaminated sites.
Filter-Ag	Clumped, non-hydrous silicon dioxide (silica) medium; lightweight and porous for general filtration of suspended solids down to 20-40 microns; requires lower backwash rates; used as an alternative to sand in multimedia filters for turbidity reduction.
Filox	High-purity manganese dioxide (MnO2) ore medium; catalytic for oxidizing and removing iron, manganese, and hydrogen sulfide; requires only backwashing (no regenerants); effective at wide pH range; used in high-contaminant groundwater polishing.
Garnet	Dense, abrasion-resistant mineral (almandine garnet) medium; used for fine mechanical filtration of particulates down to 5-10 microns; bottom layer in multimedia beds due to high specific gravity; enhances deep-bed filtration in wastewater effluent.
Graphite	Porous carbon-based medium derived from graphite; used for mechanical filtration of suspended solids and adsorption of organics/volatiles; less common but effective in specialized applications for turbidity and organic reduction.
Granular Activated Carbon (GAC)	Highly porous carbon granules produced by activating carbonaceous materials (e.g., coal, coconut shells); adsorbs organics, chlorine, tastes/odors, and VOCs; regenerable thermally; standard for post-filtration polishing in drinking water systems.
Gravel	Coarse quartz or silica particles; primarily a support/base layer in filter beds to prevent media loss; minimal direct removal but stabilizes finer media; used at the bottom of pressure vessels for structural support.
Greensand	Naturally occurring glauconite mineral with ion-exchange properties; base for manganese greensand; removes iron, manganese, and hydrogen sulfide via oxidation; regenerated with potassium permanganate; used in municipal groundwater treatment.
Humic Substances	Complex, dark-colored organic compounds formed from the decomposition of plant and animal matter, major components of natural organic matter (NOM) in soil, water, and sediments; can cause color, taste issues, and form disinfection byproducts; removed by adsorptive media like GAC or ion exchange.
Hydrocarbons	Organic compounds consisting primarily of hydrogen and carbon atoms, often from petroleum sources (e.g., oils, fuels); contaminants in water that can cause toxicity and fouling; targeted by specialized media like OrganoClay or walnut shell for removal in industrial wastewater polishing.
Ion Exchange Resin	Synthetic or natural polymers (e.g., polystyrene beads) that exchange ions in water (e.g., swap hardness for sodium); cation/anion types for demineralization, nitrates, arsenic; regenerable with brine/acid; used for targeted ion polishing in boiler feed or drinking water.
Ions	Charged atoms or molecules (cations positive, anions negative) resulting from the loss or gain of electrons; in water chemistry, they include dissolved metals (e.g., Mn²⁺) and nutrients; removed via ion exchange resins or oxidation/filtration in treatment processes.
Katalox Light	Manganese dioxide-coated zeolite medium; catalytic for removing iron, manganese, hydrogen sulfide, arsenic, and certain heavy metals; also filters particulate down to 3 microns; no regeneration needed; versatile for challenging well water with high contaminants.
KDF55	High-purity copper-zinc alloy granules; uses redox reactions to remove chlorine, certain heavy metals (e.g., lead, mercury), and inhibit bacteria; long-lasting; used in point-of-use filters or as pre-treatment in polishing systems.
KDF85	Copper-zinc alloy granules optimized for hydrogen sulfide, iron, and manganese removal; redox-based; durable and bacteria-resistant; applied in well water treatment for sulfur odors and metals.
Magnetite	Dense iron oxide (Fe3O4) medium; used for fine filtration of suspended solids down to 10 microns and oxidation of iron/manganese; high specific gravity for stable beds; often in multimedia setups for effluent clarification.
Manganese Dioxide	Generic solid MnO2 medium (natural or synthetic); catalytic oxidant for iron, manganese, hydrogen sulfide, and arsenic; requires backwashing; used in various branded forms for metal removal in groundwater.
Media	Granular or porous materials (e.g., sand, carbon, resin) used in filtration systems to trap, adsorb, or exchange contaminants from water; selected based on target constituents, with layering in pressure vessels for efficient tertiary polishing.
Microplastics	Small plastic particles or fragments less than 5 mm in size, resulting from breakdown of larger plastics or direct release (e.g., from cosmetics); persistent pollutants in water that harm aquatic life; captured by fine mechanical filters like sand or AGFM in treatment systems.
MicroZ	High-porosity zeolite variant; used for ammonia (ammonium) removal, fine sediments down to 5 microns, and iron/manganese; ion exchange and adsorption; applied in wastewater nutrient control or aquaculture.
MTM	Granular manganese dioxide medium; similar to greensand for reducing iron, manganese, and hydrogen sulfide; regenerated with potassium permanganate; used in iron-rich water polishing.
OrganoClay	A modified clay mineral (organically treated bentonite or phyllosilicate) designed as a filter media for adsorbing oils, hydrocarbons, and high-molecular-weight organics; effective in wastewater treatment for removing non-polar contaminants like PFAS or certain heavy metals.
Pecan Shell	Granular medium from crushed pecan shells; adsorbs oils, fats, hydrocarbons, and polycyclic aromatics; mechanical filtration down to 10 microns; renewable and eco-friendly; used in oily wastewater or stormwater polishing.
Precipitates	Insoluble solids formed from dissolved substances in water during chemical reactions (e.g., oxidation or pH adjustment); common in treatment for removing metals like iron or manganese; media like calcite or sand filter out these formed particles.
Pumice	Porous volcanic aluminum silicate rock; lightweight filtration medium for removing colloids, silt, and algae down to 15 microns; high void space for flow; used in multimedia beds for turbidity reduction.
Pyrolox	Natural manganese dioxide ore medium; catalytic for oxidizing iron, manganese, and hydrogen sulfide; requires high backwash rates; no regeneration; durable for high-load groundwater treatment.
Sand	Chemically inert silica particles; mechanically filters suspended solids, turbidity, and colloids down to 20 microns; middle layer in multimedia filters; widely used for particulate polishing in industrial and municipal systems.
Silt	Fine sediment particles (0.002–0.0625 mm in size) composed mainly of quartz or mineral grains, larger than clay but smaller than sand; erodes from soil and contributes to suspended solids and turbidity; removed by mechanical media like garnet or sand to prevent equipment fouling.
Suspended Solids	Insoluble particles (organic and inorganic, e.g., soil, silt, sand, plankton, bacteria, or debris) that float or drift in water without dissolving; measured as TSS; can harbor pathogens and reduce water clarity; targeted by filtration media for removal in polishing vessels.
Total Suspended Solids (TSS)	The quantitative measure (in mg/L) of all suspended solids in water that can be trapped by a filter (typically particles >2 microns), including silt, organic matter, and algae; high levels indicate poor water quality; reduced by media like sand or GAC to meet effluent standards.
Turbidity	A measure of water cloudiness or clarity (in NTU) caused by light scattering from suspended particles like silt, colloids, or detritus; high turbidity can shield pathogens from disinfection; polishing media reduce it to <1 NTU for safe drinking water.
Walnut Shell	Granular medium from crushed walnut shells; excels at adsorbing oils, hydrocarbons, and petroleum compounds; filters particulate down to 10 microns; biodegradable and effective in oily industrial wastewater treatment.
Zeolite	Natural or synthetic hydrated sodium alumina silicate with ion-exchange capacity; removes ammonia, certain heavy metals, and fine sediments; historically for softening, now for nutrient/metal polishing; regenerable; used in wastewater reuse applications.