Frequently asked
questions

Yes, CIWI achieves the same removal efficiency as conventional coagulants in terms of kg pollutants removed per kg active product dosed. The system produces iron-based coagulants (with the option for aluminum-based production), achieving same removal performance for contaminants such as phosphate, organic matter, sulfide, and heavy metals.

CIWI’s system can produce pre-hydrolyzed metal salts with polymeric structures, similar to PAC-type chemistry. Additionally, the control over iron valence (Fe²⁺, Fe³⁺ or a mix) enables further control over flock-forming properties. The active control over coagulant chemistry enables direct control over floc formation, including floc size, density, and structure. As a result, flocculation can be optimized for specific process steps such as settling, filtration, or sludge handling.

Conventional chemicals are produced as high-concentration products (e.g. ~40% FeCl₃), requiring more energy-intensive industrial processing to reach and maintain that state. These high concentration products are needed for practical transport and storage, not for the treatment process itself. By producing coagulants directly on-site at lower concentrations (<2%), CIWI avoids energy-intensive processing steps. This results in a lower overall energy footprint.

A typical FeCl₃ solution (~40%) only consists for about 14% of active iron (Fe) species that contribute to treatment and the other 86% of non-functional mass (mainly water and counter-ions). This means that roughly 8× more mass is transported than actually needed as active material. CIWI eliminates this inefficiency by producing the active coagulant directly on-site, out of steel (>99% Fe), avoiding transport of non-functional mass and so reducing logistics and handling costs.

CIWI reduces emissions by replacing industrially produced chemicals (such as FeCl₃, FeCl₂, and NaOH) with on-site production using salt, metal, and electricity. This avoids energy-intensive chemical production steps and eliminates transport. Additionally, by active control over coagulant chemistry, material and energy consumption can be further reduced. As a result, the overall carbon footprint is significantly lower compared to conventional supply chains.

The current footprint is mainly driven by steel, which has the highest CO₂ impact among the input materials. When low-carbon or green steel becomes available, the remaining emissions can be significantly reduced. Combined with renewable electricity, this creates a pathway towards near-zero Scope 3 emissions for coagulant supply, while maintaining the same treatment performance.

Salt and steel are safer, cheaper, and easier to store in large quantities compared to concentrated chemicals, they allow for several months of on-site storage instead of weeks. Additionally, these products are globally available commodities that can effectively be transported over long distances. This provides greater flexibility and reduces reliance on specific suppliers or regional production capacity.

CIWI is built as a modular system, which avoids a single point of failure and allows continued operation even if one module is offline. This makes CIWI’s solution a robust alternative, characterised by easy maintenance and low vulnerability to downtime.

CIWI only needs iron as the active input, so in practice we use simple carbon steel. Our preferred material is hot-rolled steel, sometimes referred to as black steel, typically the untreated steel product as it comes from the steel mill. This makes the input material widely available, standard, and easy to source.

No, chemical analysis have shown that the presence of heavy metals and other impurities in the resulting coagulant were in the same range as conventional ferric chloride products used for water treatment. In other words, the contribution is negligible in practice and comparable to existing market products, including grades used for drinking water applications.

By producing chemicals on-site, CIWI removes much of the conventional supply chain and cuts out around 86% of its steps. This reduces dependence on centralized factories, long-distance transport, and external disruptions, making treatment operations more resilient to shortages, delays, and market volatility.

Yes, CIWI can reduce the introduction of acid and chloride (Cl⁻) compared to conventional chemicals, reducing salinity increase and downstream acidification. By active control over coagulant chemistry, including iron valence (Fe²⁺, Fe³⁺ or a mix) and proton (H⁺) ratio, product characteristics are optimized for its intended purpose.

CIWI replaces purchased chemicals with on-site production, using salt, metal, and electricity. These raw materials have a significantly lower cost base compared to bulk chemicals, such as FeCl₃, FeCl₂, and NaOH, which include industrial processing, logistics, and supplier margins.

The impact are calculated using a mass balance approach based on the Greenhouse Gas Protocol, combined with verified CO₂ datasets (e.g. Ecoinvent). This allows a transparent comparison between conventional chemical supply and CIWI’s on-site production. Based on this methodology, switching to CIWI can result in up to ~50% reduction of Scope 3 emissions when renewable electricity is used at the treatment plant.

CIWI can contribute to circularity in several ways. The first step in circularity is reduction, reducing the use of resources by active control over coagulant chemistry, allowing for reduced acid usage. Lowering acid consumption, subsequently reduces the energy and salt consumption. In addition, alternative material inputs can support circularity: once properly processed, secondary steel streams may become suitable feedstock, and salt input can also come from brine streams such as reverse osmosis concentrate. The system can further support nutrient recovery pathways in water treatment. At the same time, not all loops are closed yet: the sludge produced after treatment is not currently reused, although this is an area we are investigating.

Chemical risk strongly depends on concentrations, as Paracelsus’ principle states: “the dose makes the poison.” Even familiar substances such as caffeine, and in extreme cases even water, can become harmful when the dose is too high. The same logic applies here: at lower concentrations, there are fewer reactive species per unit volume, reducing corrosivity, heat release during contact, and the severity of harm in case of accidental exposure. Low-concentration chemicals are inherently safer to handle, store, and dose in practice. EU CLP classification reflects this reduced hazard, but the improved safety is rooted in the underlying chemistry itself.

At the concentrations used, only mild and manageable risks remain. The iron-based coagulant may be corrosive to metals, and the NaOH solution (0.5–2%) may cause skin and eye irritation.

These risks are well understood and can be handled with standard precautions. The chemicals are not subject to high-risk storage regimes and related permits at these concentrations, further simplifying safe operation.

CIWI enables treatment plants to produce coagulants and NaOH on-site, from salt, metal, and electricity, eliminating the need to buy, store and handle concentrated bulk chemicals. While conventional chemicals are typically stored for only 1 to 2 weeks due to practical constraints, salt and steel can be stored safely and cost-effectively in much larger quantities. This allows plants to extend on-site supply from weeks to up to ~3 months within the same storage footprint.

Conventional chemicals such as FeCl₃ and NaOH are characterised by high concentrations, which introduces chemical hazards for operators, storage, and transport. CIWI produces these chemicals on-site at low concentrations (typically <2%), targeting chemical hazards at the source, significantly reducing hazard severity while maintaining the same treatment performance.

CIWI leverages electricity as a key input, which is increasingly decentralized. Unlike large chemical production facilities that consume energy at industrial scale and often depend on large, fossil-based power sources, CIWI operates at kilowatt scale and can be powered by local renewable energy such as solar, supported by on-site storage such as batteries. This allows treatment plants to partially control their energy supply and improve operational independence. Even modest storage capacity can help mitigate grid constraints, enabling stable and more autonomous operation when combined with locally stored raw materials.

No. Even if all coagulant demand today were supplied with CIWI’s approach, the required steel volume would only represent a minimal fraction at industrial scale. As an illustration, it would represent less than 0.5% of Europe’s annual steel production.

No, not in general. Scrap metal is often contaminated and comes in many different sizes and shapes, while CIWI requires a clean and consistent feedstock. From a circularity perspective, scrap is also often better used through conventional recycling: remelted, refined, and reused as steel. That route preserves material quality and is already common practice. The largest share of steel’s carbon footprint comes from the conversion of iron ore into primary iron, not from the later steelmaking and rolling steps, so recycling scrap through established steel production routes is typically the more sustainable option.

CIWI is relevant for any treatment plant that uses coagulants (i.e. metal salts), whether in municipal or industrial water and wastewater treatment. The system targets the same pollutants typically removed by coagulation, such as phosphate, suspended solids, organic matter, sulphide, and heavy metals. In practice, we currently advise to implement CIWI systems from dosing capacities of about 0.5 kg Fe/h (2.5 L 40% FeCl₃/h), as smaller applications become less cost-effective. This typically corresponds to treatment plants from 100 to 1,000 m³/day, depending on water quality and dosing demand.

Containerization is practical for transport and fast deployment, but it is not required. The system can also be installed in an existing or newly adapted building.

The system is more technically advanced than a simple storage tank with a dosing pump, but maintenance remains practical. Pumps, valves, and actuators are relatively small and can be swapped by one mechanic. If a component fails and a spare part is available on-site, repair is typically possible within half a day. Because the individual components are compact, for example, the largest pump weighs less than 10 kg, spare part handling and inventory are straightforward and not expensive.

The footprint depends on the required production capacity. Our smallest unit of 0.5 kg Fe/h, including product conditioning, fits in a 10 ft container, while a 5 kg Fe/h system can easily fit in a 20 ft container. For many applications, we expect a footprint of around one 20 ft container, while larger installations may require two 40 ft containers.

Each production unit is available in standard nominal capacities of 0.5, 1.25, or 2 kg Fe/h. Depending on the required dosing rate, modules can be added or removed to scale the system up or down in a straightforward way. This makes it possible to match the installation to both current demand and future expansion without redesigning the full system.

Integration complexity is relatively limited and is mainly related to de concentrations of the dosed products. In most cases, only the dosing pump and dosing line need to be adapted, while the existing dosing setup can remain in place alongside the new system. The required dosing lines are still small in diameter (we expect typically up to around d20), but the dosing rate shifts from conventional L/h ranges toward L/min depending on the application. Dosed volumes, as for conventional dosing chemicals, typically remain below 0.1% of the total treatment plant flow.

Yes. Service contracts can be included for dosing support and optimisation, maintenance, and operational assistance, depending on the level of support the customer requires.

Yes. In addition to iron-based coagulants, CIWI can already produce aluminium-based coagulants as well as NaOH and HCl for pH control and other water treatment applications. We are also investigating the production of flocculants by combining our technology with another circular resource: cellulose recovered from sewage treatment, such as fibres from used toilet paper. In the longer term, CIWI aims to become a platform for the on-site production of the most widely used treatment agents in water treatment.

Both are possible. CIWI can be offered through a direct purchase model or through lease-based arrangements, depending on the customer’s preference and project setup.

There are several options. You can provide us with water samples and we can test the chemistry in our lab, or we can supply product samples for you to test in your own process. We also have mobile container-based systems that can be installed on-site, allowing you to test the solution in practice at your treatment plant.

This can be arranged either way. CIWI can supply the salt and steel as part of the offering, or the customer can source these inputs directly.