Filter contaminant retention – expert report Aquaphor & Q1

1 · What makes an activated carbon block

Highly compressed activated carbon with an enormous internal surface area – the basis for high retention

An activated carbon block is not a container full of carbon granules. It is a solid, highly compressed body made of the finest activated carbon powder. It is precisely this construction that determines what a filter can do – and what it cannot.

The internal surface area

Activated carbon is typically made from coconut shell and activated with steam. This creates a network of extremely fine pores. The resulting internal surface area – calculated by the BET method – is around 1,300 to 1,400 square metres per gram.

Three working principles

Why proximity is decisive

Adsorption is based on the London dispersion force, a form of the van der Waals force acting between molecules. It works similarly to gravity – but only over extremely short distances. The distance between the carbon surface and the molecule to be bound must therefore be very small.

This force is additive: it is the sum of all intermolecular attractive forces. Direct contact and additive effect together give activated carbon the strongest physical adsorption forces of all known materials. In principle, any compound of molecular size can be adsorbed.

Block instead of loose fill

Manufacturing makes the difference

In a high-quality process, the activated carbon powder is coated at discrete points with a porous binder and then compressed into shape. The binder content remains below 8 percent. This brings two advantages:

• The pores of the activated carbon do not clog – the internal surface remains usable.
• More than 90 percent active substance is actually available for filtration.

Not only the surface area counts, but also the grain size

Above a grain size of 100 µm, satisfactory adsorption results can no longer be achieved – in the swimming-pool sector, not even DIN 19643 could be met. Powdered activated carbon in the range of 0 to 90 µm is therefore used, most of it at around 40 µm. This is exactly why even a 5 µm activated carbon block already has a very high adsorption capacity.

Absolute or nominal – an important distinction

When comparing filter products, check whether a pore size is stated as “absolute” or “nominal”. The number alone says little – two filters with an identical figure can work completely differently.

2 · The design of the K7B / Aquadea-Q1 cartridge

Two filter stages in one housing – adsorption and germ barrier

The K7B / Aquadea-Q1 cartridge works in two stages. One half of the housing holds the activated carbon block with AQUALEN® technology, the other half a hollow-fibre membrane. The two stages perform different tasks – only together do they deliver the overall result.

Stage 1Activated carbon block with AQUALEN®	Stage 2Hollow-fibre membrane germ barrier
0.8 µmabsolute, throughout	0.1 µmbacteria retention log 6

Schematic design of the K7B / Aquadea-Q1 cartridge – flow direction from left to right

Stage 1 · Activated carbon block with AQUALEN®

Highly compressed activated carbon combined with AQUALEN® fibres. This stage performs the adsorption: organic substances, chlorine, pesticides, heavy metals. The filter rating is 0.8 µm absolute – consistently across the entire block, not graded from the outside inwards. What “absolute” means and why it is decisive is explained in section 1.

The patented AQUALEN® process gives rise to additional synergy effects. The most important concerns heavy-metal ions: desorption is fundamentally avoided. Desorption is the process by which atoms or molecules leave the surface of a solid again. In practice this means: once bound, heavy metals are held and not washed back into the water flowing through.

Stage 2 · Hollow-fibre membrane as germ barrier

The second half of the cartridge is a hollow-fibre membrane from a Japanese manufacturer with a pore size of 0.1 µm. It works purely mechanically: whatever is larger than the pore does not get through.

Bacteria retention is log 6. This means a reduction by six orders of magnitude – of one million germs in the inlet, statistically one passes the membrane. This corresponds to a retention of 99.9999 percent.

How to read the following measured values

3 · Test basis and standards

NSF/ANSI Standard 42 Aesthetic effects	Point-of-use (POU) and point-of-entry (POE) systems for the reduction of aesthetic or non-health-related contaminants: chlorine, taste, odour and particles.
NSF/ANSI Standard 53 Health effects	POU and POE systems for the reduction of health-related contaminants such as Cryptosporidium, Giardia, lead, volatile organic chemicals (VOC) and methyl tert-butyl ether (MTBE).
LGA	In selected products, the AQUALEN® activated carbon blocks are LGA-certified.
DIN 38404-10	Calculation of the calcite dissolution capacity (section 11).
EN ISO 11369 F12	Test method for the pesticide values of the K7B / Aquadea-Q1 cartridge (section 5).
EN ISO 11885 E22	Test method for the heavy-metal ion values of the K7B / Aquadea-Q1 cartridge (section 5).

Test object: Aquaphor activated carbon blocks with AQUALEN® technology.

4 · Metals and heavy metals

Test standard analogous to NSF/ANSI Standard 53 · In-house verification, AQUAPHOR Corp. laboratory, St. Petersburg · Flow rate 2 l/min with one cartridge

Parameter	Reduction	Note
Lead	up to 99 %	NSF/ANSI Standard 53
Copper	up to 99 %
Uranium	over 97 %
Aluminium	over 95 %
Nickel	up to 95 %
Zinc	up to 95 %
Iron	50 – 95 %	depending on pH value
Manganese	50 – 95 %	depending on pH value

5 · Extended laboratory values – K7B / Aquadea-Q1 cartridge

Further contaminants · Reference values¹ · Examples of reduction

Organic substances

Parameter	Reduction
Phenol	up to 99.5 %
Chloroform	up to 99.5 %
Benzene	up to 99 %

Pesticides²

Parameter	Reduction
Terbuthylazine	89.3 %
Isoproturon	89.1 %
Sebuthylazine	88.3 %
Atrazine	84.5 %

Heavy-metal ions³

Parameter	Reduction
Cadmium	99.7 %
Copper	99.2 %
Nickel	99.1 %
Lead	98.4 %

Hormones⁴

Parameter	Reduction
17-α-Ethinylestradiol	99 %

6 · Retention over the filtrate volume

Retention rates as a function of the volume of water already filtered · Flow rate 1.5 l/min

7 · Substantially reduced substances

Results Aquaphor Corp., St. Petersburg, according to NSF protocol Aquaphor Corp.

Why these particular substances were selected

• Chlorine represents water disinfection.
• Benzene represents the field of hydrocarbons.
• Phenol represents organic substances. At a higher level these are grouped as TOC (total organic carbon) and VOC (volatile organic compounds), sum parameters that reflect the contamination of the water.
• Lead serves as an example of heavy metals.
• Lindane represents the field of pesticides, fungicides and herbicides.
• Iron – iron retention to the extent stated can be regarded as a special quality feature.

8 · PFOA and PFOS

According to the available tests, perfluorooctanoic acid (PFOA) is retained at around 87 to 99 %.

On the cleaning effect of activated carbon blocks against PFOA and PFOS in private drinking water, measurements are available from, among others, the Hessian Agency for Nature Conservation, Environment and Geology (HLNUG).

9 · Polycyclic aromatic hydrocarbons (PAH)

PAH are considered harmful to health and are classified as potential carcinogens. These molecular compounds of carbon and hydrogen atoms are formed, for example, in house fires when mattresses, curtains, wooden beams, plastic or other objects made of organic materials burn. They also enter water through leaking vehicle fluids.

Activated carbon blocks are frequently used to remove PAH from water. At a suitable flow rate, a safe and efficient reduction can be achieved.

Applications of activated carbon blocks in water treatment systems

• Benzene, toluene, xylene (BTEX)
• Chlorinated hydrocarbons (CHC)
• Chlorofluorocarbons (CFCs)
• Polycyclic aromatic hydrocarbons (PAH)
• Phenols
• Pesticides

10 · Where the contamination comes from

According to the current state of knowledge and technology, traffic areas are to be regarded as a major source of water pollution from stormwater discharges. Runoff from traffic areas is contaminated with organic pollutants from vehicle emissions, atmospheric pollution and other sources – PAH, mineral oil hydrocarbons (MOH), methyl tert-butyl ether (MTBE) as well as plant protection products and pesticides. Added to this is heavy contamination with heavy metals. The pollutants are present partly in dissolved form, partly bound to particles.

Typical contaminants in stormwater runoff from paved traffic areas

Substance	Sources
Inorganic pollutants
Zinc (Zn)	Tyre wear, brake pad wear, exhaust gases, corrosion losses from vehicles, traffic signs and crash barriers
Copper (Cu)	Tyre wear, brake pad wear, exhaust gases, corrosion losses from vehicles
Lead (Pb)	Fuel drip losses, exhaust gases, road surface wear
Nickel (Ni)	Brake pad wear, road surface wear, catalytic converters, corrosion losses from vehicles
Chromium (Cr)	Tyre wear, brake pad wear
Cadmium (Cd)	Tyre wear, corrosion losses from vehicles
Platinum (Pt)	Catalytic converters
Organic pollutants
Mineral oil hydrocarbons (MOH)	Drip losses of engine oils, fuels and antifreeze, exhaust gases, evaporation losses
Polycyclic aromatic hydrocarbons (PAH)	Tyre wear, exhaust gases as residues of incomplete combustion, road surface wear
MTBE / ETBE	Fuel drip losses, exhaust gases as residues of incomplete combustion
Plant protection products and pesticides (PPP)	Carried over from agriculture

11 · Calcite dissolution capacity

Calcite is a crystal modification – a form – of calcium carbonate (CaCO₃). The calcite dissolution capacity is the mass of calcite that one litre of a given water can dissolve. It is then invisibly dissolved as a salt. It is calculated according to DIN 38404-10 and gives an indication of the corrosion-chemical behaviour of a water.

For calcite-depositing waters – i.e. waters that contain too much lime and precipitate it – the value for the calcite dissolution capacity becomes negative.

Calcite saturation

The state of a water in which, in contact with calcite, neither dissolution nor deposition of calcite takes place: Dc = 0. Calcite saturation is also referred to as the lime–carbonic acid equilibrium.

Saturation pH value

Also called the pH value of calcium carbonate saturation or the pH value of calcite saturation:

CaCO₃ + H⁺ ⇄ Ca²⁺ + HCO₃⁻

With galvanised steel pipes and copper pipes there is a clear correlation between the pH value of the water and the zinc or copper concentrations that occur in drinking water after stagnation: the lower the pH value, the higher the levels of these heavy metals in stagnant water. In softer waters the same tendency applies to the solubility of lead.

To protect the consumer from excessive heavy-metal concentrations in drinking water, it therefore makes sense to raise the pH value as far as possible. Raising it above 7.8 is not necessary, however. The technical limit is the pH value at which a water enters the range of calcite deposition.

12 · Why a ppm meter hardly “sees” the filter

Conductivity, TDS and contaminants – what the number on the meter tells you and what it does not

Many customers check their filter with a small conductivity meter (reading in µS/cm or as “ppm” or TDS). The result is then often surprising: before and after the activated carbon block, the reading is almost the same. This is not a shortcoming of the filter – it is down to what such a device actually measures.

13 · Your advantages

• No turbidity – drinking water with the best taste and odour
• Two filter stages in one cartridge – adsorption and germ barrier
• Hollow-fibre membrane with 0.1 µm pore size: bacteria retention log 6 (99.9999 %)
• Activated carbon block with 0.8 µm absolute filter rating, throughout – tested to NSF Standard 42
• Protection of appliances – fewer failures thanks to prevented particle ingress
• Easiest handling thanks to quick-change system
• Innovative locking handle with secure latching

To the Aquadea activated carbon block filters

14 · Important notes

1. The substances listed may, but need not, be present in the water.
2. The reduction results may differ in practice – both higher and lower reductions are possible. Water composition, total filtrate volume, concentration of the measured substance, flow rate and temperature may differ from laboratory conditions. The results listed are therefore to be understood as reference values. No two waters are the same.
3. The results refer exclusively to the stated test object and the described test conditions. Publication or reproduction of extracts from this report only with written permission.
4. In general, note that every activated carbon block has a limited adsorption capacity. Tap water supplied in accordance with the German Drinking Water Ordinance may contain traces of these contaminants; for their removal, the capacity of the activated carbon block is sufficient within the filter replacement intervals and volume specifications.