Contamination of Wastewater
Water discharged from various industrial processes during manufacturing, cleaning and other commercial operations may contain dissolved substances. These include chemicals, oils, pesticides, pharmaceuticals, synthetic organic chemicals, and other industrial by-products that are toxic.
They can then have hazardous effects on human and aquatic life because of possible bioaccumulation in the food chain. These may include what are classed as persistent, bio accumulative and toxic substances (PBTs) which are compounds that have high resistance to degradation.
In addition to wastewater discharged directly from industrial processes directly, there are numerous other pathways where our natural waters can become contaminated. These include agriculture runoff wastewater from agrochemicals such as fertilizers, pesticides, herbicides and crop residues, animal wastes, and effluents. This is considered a significant source of water pollution when excess water runs off the fields to nearby water sources.
In addition, stormwater runoff wastewater, following heavy rainfall or a storm event, is also becoming more important. This runoff may contain many toxic pollutants such as oils, pesticides, and chemicals. These can get washed through drains and discharged into nearby natural waterways often without any treatment.
Therefore, all these wastewater discharges can carry a variety of pollutants that can adversely affect the ecology of receiving lakes, streams, and rivers. Effective treatment of these wastewater discharges is important for the environment and our drinking water. This is because these water sources often become the feed water for our water treatment works.
Wastewater Regulations
Wastewater treatment regulations in Europe have undergone significant changes in recent years, in particular the Industrial Emissions Directive and the Urban Wastewater Treatment Directive.
The original Industrial Emissions Directive, known as IED or Directive 2010/75/EU, was adopted in 2010. This aimed to control environmental pollution by setting discharge limits for emissions, specifically for industrial premises.
The new Industrial and Livestock Rearing Emissions Directive 2024/1785 (IED 2.0) amends Directive 2010/75/EU. This is now the main EU instrument aiming to reduce these emissions into air, water and land.
The Urban Wastewater Treatment Directive – 91/271/EEC, adopted in 1991, related to the treatment and discharge of urban wastewater and certain industrial sectors. This Directive has been revised following an evaluation and adapted to the newest standards. It aimed to further improve water quality by addressing remaining urban wastewater pollution with stronger compliance requirements. This still requires final ratification but is expected to be adopted in 2024.
Wastewater Treatment with Activated Carbon
Filtration through a bed of activated carbon enables a wide range of pollutants, including many trace substances to be removed or adsorbed before release into the environment. Adsorption is the process by which molecules are removed from the liquid and concentrated on a solid surface, in this case activated carbon.
Activated carbon is considered a very effective technology for the removal of many organic compounds from wastewater through adsorption. In this process, organic pollutants are concentrated inside the porous activated carbon material where they remain until they can be safely destroyed in the reactivation process.
The adsorbability of a molecule improves with increasing molecular weight which means that many organic chemicals are very well adsorbed onto activated carbon. In particular, this includes those that are more complex with a higher number of functional groups, such as double bonds or halogen compounds. The better the compound is adsorbed or the more of the compound that the activated carbon can adsorb, the longer the activated carbon lasts.
What Wastewater Pollutants Can Be Removed Using Activated Carbon?
Activated carbon, in granular or powder form, is highly effective for the removal of a wide range of organic and hydrocarbon pollutants, non-biodegradable compounds and micropollutants from wastewater. These include pesticides, herbicides, insecticides, fungicides as well as oils, colour and odour.
Some of the many pollutants that can be efficiently removed with activated carbon technology are noted in the table below:
| 2,4-D (Dichlorophenoxyacetic acid) | Di ethylhexyl phthalate (DEHP) | Mono butyl tin trichloride (MBTC) |
| Acetone* | Dimethyl formaldehyde | Naphthalene |
| Acetophenone | Dimethyl sulphate (DMS) | Nitrobenzene |
| Acetic acid | Dinitro toluene (DNT) | Nitrophenol |
| Acetonitrile | 1,4-Dioxane | Nonylphenol |
| Acrylonitrile | Dioxins | Octyl phenols |
| Alkanes | Diphenyl carbazide (DPC) | Organotin compounds |
| Alkenes (Olefins) | Dissolved organic carbon (DOC) | Phenol (Hydroxybenzene) |
| Aniline | Ethyl acetate | Phenolic compounds |
| Anthracene | Ethyl ether | Phenylalanine |
| Aromatic compounds | Ethylbenzene | Phthalic acid |
| Bentazone | Fatty Acids | Polycyclic aromatic hydrocarbons (PAHs) |
| Benzene | Fluoranthene | Polyethylene glycol |
| Benzoic acid | Glyphosate | Propazine |
| Benzophenone | Grease* | Pyridine |
| Benzopyrene | Hexane | Simazine |
| Benzotriazole | Hexanone (MBK) | Solvents |
| Benzyl alcohol | Isooctane | Sterols |
| Benzyl butyl phthalate (BPP) | Melamine | Styrene |
| Bisphenol A (BPA) | Metolachlor | Tetrahydrofuran* |
| Bipyridine | 4,5 Methyl benzotriazole | Toluene (Methylbenzene) |
| Bis (2-Ethylhexyl) Phthalate | Methylbenzylamine | Total Organic Carbon (TOC) |
| Butylbenzene | Methyl butane | Tributyltin chloride (TBTC) |
| Chemical Oxygen Demand (COD), | Methyl ethyl ketone (MEK) | Trimethylbenzene |
| Chlorothalonil | Methyl isobutyl ketone (MIBK) | Trinitrotoluene (TNT) |
| Cresol | Methyl naphthalene | Vinyl acetate |
| Cybutryne | N-methyl-2-pyrrolidone (NMP) | Xylene |
| Cyclohexane | Methyl-tertiary-butyl ether (MTBE) | Xylenol |
| Di-n-butyl phthalate |
* Check with Chemviron technical representative for further information
Granular activated carbon filters are also effective treatment technologies for removing halogenated organic compounds and PFAS compounds from water.
Some of these organo-halogen pollutants that can be effectively removed with activated carbon technology are noted in the table below:
| Adsorbable Organic Halogens (AOX) | Chlorotoluene | Per-fluorinated compounds |
| Bromate* | Dibromo-3-chloropropane | Per- and polyfluoroalkyl substances (PFAS) |
| Brominated diphenyl ethers (BDE) | Dibromochloromethane | Perfluorooctanoic acid (PFOA) |
| Bromodichloromethane | Dichlorobenzene | Perfluoro octane sulfonate (PFOS) |
| Bromoform | Di chlorocresol | Polychlorinated biphenyls |
| Bromophenol | Dichloroethane | Polychlorinated dibenzofurans |
| Chlorinated compounds | Difluoro benzophenone | Polychlorinated dibenzo-p-dioxins |
| Chloramines | Epichlorohydrin | Polychlorinated naphthalene’s (PCN) |
| Chloroalkanes | Firefighting foam (PFAS or PFHxA) | Tetrachloroethane |
| Chlorobenzene | Hexachlorobutadiene | Tetrachloroethylene |
| Chloroethane | Methyl chloride (Chloromethane) | Trichlorobenzene |
| Chloroform | Methylene chloride (Dichloromethane DCM) | Trichloroethylene |
| Chlorophenol | Pentachloro benzene (PeCB) | Trifluoroacetic acid (TFA) |
| Chloropropane | Pentachlorophenol | Trihalomethanes (THMs). |
* Check with Chemviron technical representative for further information
How Can Chemviron Help You?
The selection of the most appropriate activated carbon may depend on several factors. This includes the types and range of compounds or contaminants that need removal, their concentrations, and the pH of the waste stream involved.
With our depth of experience in this field, Chemviron are able to work with you to assess the effectiveness of the treatment regime considered. However, each water source is different and may contain different combinations of pollutants. It may therefore be appropriate to first carry out a laboratory test on a representative water sample. This would assess the likely carbon performance and so consider the most appropriate technical solution.
Isotherm testing to evaluate the removal of organics from water is quick but often is more effective at comparing different carbons than generating definitive performance results. Pilot testing is much more effective at indicating likely carbon usage but can be time-consuming. Chemviron can, however, provide support and advice using our pilot units, which include our range of smaller mobile carbon filters.
To shorten the process, the Accelerated Column Test (ACT) was developed by our company. This is an improved technique that combines the speed of an isotherm test, with the accuracy of a pilot column. The ACT is a bench-scale procedure that simulates a full-scale system and can provide breakthrough data for testing the removal of organic impurities in water but in a much shorter time. The ACT technique can be applied to evaluate contaminant removal in both drinking water and wastewater.
As we have been running these tests for well over forty years, Chemviron has built up an extensive reference library to provide supporting data for this application.
Spent Carbon Recycling and Mobile Carbon Filters
Once the granular activated carbon installed in the filter has become saturated with organics and less effective in operation, it can be recycled by thermal reactivation for reuse. Reactivation involves treating the spent carbon in a high-temperature furnace where the undesirable organics on the carbon are thermally destroyed. Recycling activated carbon by thermal reactivation is a sustainable and environmentally friendly technology that meets all our objectives to minimise waste and reduce CO2 emissions.
If this is a new or localised treatment application, why not consider using our mobile carbon filters that are available for rental. These can be used both as a site treatment vessel and then used to transport carbon to and from the site, without the need for any on-site carbon exchange. Chemviron has a range of these mobile carbon filters of different sizes and capabilities including those for the treatment of corrosive liquors.
If you need technical support to evaluate your likely treatment options, help with the choice of activated carbon, the use of our reactivation service, the help of our mobile carbon filter service or just some further advice, please contact us – contact our technical team.