Best Practices Resource Recovery from Water

Learning from Best Practices on Resource Recovery from Water

Driven by environmental, economic, and ecological benefits, resource recovery from waste has started to draw attention worldwide. Recovering resources from water and wastewater can provide an alternative and economically viable source of resources supporting the resilience of human and natural systems under water stress. Resources from the water cycle can be water itself, energy (organic or thermal) and components such as nutrients and metals.

A range of new initiatives are underway to promote and accelerate the development and uptake of resource recovery science and technologies. Innovation on resource recovery in the water cycle has been developing fast, but examples of large scale and marketable applications from current scientific innovations are scarce. The key issue here is how to move from research to practice, while also taking into account: a. the market potential for the resource recovered, b. appropriate public policy, regulation and institutional arrangements to support and accelerate resource recovery and c. stakeholders’ needs well integrated with technologies, markets, policy, new initiatives, current research and practice.

A best practice, in this case, is a proven technology on resource recovery, applied at full scale, from supply to demand, which can serve as an excellent example for another country, area, company, etc.

This web-based tool shows best practices on resource recovery from water. The goal is to share and exchange knowledge and experience, with the ultimate goal to learn from best practices and make new innovations on resource recovery possible.

IWA Resource Recovery Cluster aims to bring together R&D, water industry and materials users, and to promote economically and environmentally attractive approaches to resource recovery.

Roest-Kees-001-255x255

Contact

Kees Roest
Senior scientific researcher
+31 (0)30-6069531
Kees.Roest@kwrwater.nl 

Best Practices

WATER

This category shows best practices from water reuse, both industrial and potable water reuse.

Orange Water County District – groundwater replenishment system

FACTSHEET

Country: USA, Orange County
Sector: Waste, ground and drinking water
Loads: 265,000 m3/day

Short Description

Wastewater effluent is being purified in the Advanced Water Purification Facility, where it is discharged into groundwater aquifers to later on be used as drinking water for residents in the surrounding area.

Technology

The AWPF uses a three-step purification process which includes microfiltration, reverse osmosis (RO) and a combination of ultraviolet light and hydrogen peroxide. The microfiltration is a low-pressure filter that sieves out bacteria and protozoa while the RO remove dissolved minerals and pharmaceuticals. The last step with UV-light destroys potential harmful constituents through penetrating cell walls of organisms and thus inducing cell death. The addition of hydrogen peroxide results in oxidizing organic compounds for ultimate removal from water. Calcium hydroxide, which is hydrated lime in powder form is added along with cationic polymers to stabilize and buffer the final product water.

One advancement that the GWRS beholds is the seawater intrusion barrier (see Figure 4.3) (Lenker et al, 2014). As more water is being pumped out of the basin, the risks of salt water seeping into the basin increases (GWRS, 2013). 114,000 m3/day out of the 265,000 m3/day that is being produced is pumped into injection wells where it is serves as a barrier for seawater. The rest of the water is distributed to percolation ponds designed for the water to pass through gravel and sand beds before augmenting the principal drinking water supply aquifer. The groundwater is later pumped to over 400 wells used by cities, local water agencies and other groundwater users.

Stakeholders

Orange County Water District (OCWD): The Orange County Water District (OCWD) was formed in 1933 and serves more than 2.3 million residents in Orange County [5]. It came about as an act of the California State Legislature and is responsible for managing and protecting groundwater basins in Orange County.

Orange County Sanitation District (OCSD): OCSD purifies secondary effluent. Together with Orange County Sanitation District (OCSD), OCWD has developed a Groundwater Replenishment System (GWRS). The system began operations in January 2008 and the GWRS is today the world’s largest used water purification system for indirect potable reuse (Chalmers and Patel, 2013).Their treatment facility, known as the Advanced Water Purification Facility (AWPF), discharges treated water into groundwater aquifers to later on be used as drinking water for residents in the surrounding area.

In regards to social aspects, the District made noteworthy efforts in gaining public acceptance which has resulted in the community’s approval of the project. The public outreach program began already in 1997, years before the system was designed, to educate people about the positive aspects of water reuse.

Financial impact

The Factory was also the first in the world to perform advanced treatment of used water for injection into coastal drinking water aquifers.

Environmental impact

There was a demand to increase the available pool of water, to decrease the demand of the imported water as well as a prevent seawater intrusion.

Source: IWA Resource Recovery Cluster Compendium (to be published, 2014)

Water reuse at Yatala brewery

FACTSHEET

Country: Australia, Queensland
Sector: Industrial water
Loads: Annual recycled water 420 ML of 820 ML annual municipal water consumption

Summary

With a beer production capacity of 450 ML/yr, Carlton United Breweries (CUB) at Yatala, south of Brisbane, is one of the largest breweries in the country. Using 2.4 L water/L beer, it is leading the way internationally in demonstrating world best practice water consumption. Historically this ratio was around 7-10L water/L beer, and internationally, the average is currently 3-6L water/L beer.

Technology

Advanced Water Treatment – Anaerobic + Aerobic biological treatment followed by Micro filtration, Reverse Osmosis , advanced oxidation and chlorination.

Internal optimisation of all water usages.

Stakeholders

Gold Coast City Council; Research sector; Policy makers; Public.

Risks to reputation of business from public misconceptions – recycled water does not contact product. Long term ongoing emphasis on training and awareness at all levels. Biggest barrier is perceptions attached to consumption of treated water. The final product from our plant is superior in all parameters to reticulated supply. Yuk factor still applies however. World needs to grow up.

Financial impact

Project costs for overall plant spread over 20 year period and justifications mixed from stay in business through environmental and economic benefits. As recycling costs compensated by reductions in municipal headworks charges this is more complex.

Environmental impact

Reduction in carbon footprint related to on site anaerobic waste treatment against municipal aerobic treatment. Untreated waste equivalent to approximately 200,000 EP. Net gain in energy from biogas generation.

Additional reference used: waterrecyclinginvestment.com

ENERGY

This category shows best practices on energy recovery from the water cycle. This can be thermal energy, e.g. out of the sewer. Or a case on energy neutral/positive wastewater treatment.

Energy and phosphorus recovery from potato wastewater

FACTSHEET

Country the Netherlands
Sector Industry wastewater
Loads 3 million m3 biogas and 1500 kg struvite/d

 

Treatment plant

Wastewater from potato industry is treated anaerobically and energy and phosphorus is recovered. Recently the struvite is blended and turned into the product ‘Vitalphos’.

The construction of the plant (phospaq and anammox) was completed in 2006. The 3 UASB reactors have been in function since 1982. Before 2006 the Aviko wastewater was only treated anaerobically and turned to the municipal treatment plant.

Vitalphos plant started up in 2014, in the Vitalphos plant the struvite is upgraded to a fertilizer by drying the struvite and adding various natural materials.

Technology

  • Anaerobic digestion for energy recovery
  • Biological biogas scrubber for sulfur recovery (ThioPaq)
  • Struvite precipitation for phosphorus recovery (PhosPaq)
  • Production of Vitalphos from the struvite: drying and blending with various natural materials, custom made (Marathon organic buffer complex, patented)
  • Anammox for N removal

Stakeholders

The struvite recovery is in use since 2006. A lot of experience is gained since the start up. Good operational knowledge is needed for successful struvite recovery, this also counts for the Vitalphos plant.

Crucial was the involvement of an agricultural and retailer expert.

Financial impact

The Industry pays for the treatment of the wastewater (imposed in the wastewater discharge permit) by outsourcing this activity to another company (Waterstromen).

The cost/benefit analysis is very specific for the local situation. Nothing can be said about this.

Waterstromen

Waterstromen owns and operates several wastewater treatment plants.

Dried pellets using warmth from engine during transport


FACTSHEET

Country the Netherlands
Sector Drinking water
Loads 10-15% is dried in 2014

 

 

 

Description

Softening pellets are the by-product of the softening of drinking water. Until recently, there pellets were sold without any processing like drying, grinding and/or sieving. In other words, the pellets were brought to the market supply driven, not demand driven.

However, with an ambition to valorise the softening pellets further, it seems unavoidable to process the pellets in order to meet specifications of potential appliers of the material. One of the major challenges in this case is to find an application with the highest added value (environmental, financial) with the lowest processing efforts.

Some customers want to pellets to be delivered ‘dry’, whereas they normally have a moisture content of 3-4%. They want them dry, for example because wet pellets cost more energy in thermal processes of because the wet pellets stick together and cause clotting.

However, the processing step ‘drying’ is expensive (storage wet, drying process, storage dried, extra transport) and is not environmental friendly because of the energy use. About a year of research resulted in a relative simple answer to these challenges: drying on board of the truck with the warmth from the engine. It is cost effective, because there is no need for storage and extra transports. The warmth from the engine would have been emitted to the air, so using this warmth makes the use of (extra) fossil resources unnecessary.

Since April 2013 several customers are supplied with dried pellets, giving the pellets an higher economic value and making higher grade applications possible.

Technology

Shared service centre Reststoffenunie and SME Van Lijssel took the initiative to develop a truck where the pellets can effectively be dried on board with the warmth from the engine. The technical challenge was mainly to get this warmth evenly spread over the load in the truck. About 10-15% of the available pellets in the Netherlands are dried on board of a truck in 2014. The moisture content is lowered from 3-4% at loading to < 1% delivered at the client.

The production plants didn’t have to make any (technical) adjustment. Evidently, the moisture content at the moment of loading has an impact on the duration of the drying process. Therefore, agreements have been made with these production plants to hold the purging of water some hours before loading the pellets.

Stakeholders

  • Buyers: Wanting a secure supply of dried pellets. They were asked to give commitment
  • Transport company: Invested in trailer & truck. Brought in knowledge:
  • Research company: Studied the possibilities and advised the adjustments of the trailer.
  • Suppliers: commitment on supplying for a longer period of time, guaranties on the moisture content of the pellets.

Financial impact

The adjustment of the trailer cost some 40-50 k€, the research excluded. The added value of the dried pellets resulted in a payback time of less than 1 year. Essential is, however, that the truck is fully engaged with the transport of softening pellets. Cleaning because of the transport of other material (cost, contamination risk) or standstill (cost) is not an option.

The research costs were 50-75k€, the adjustment of the trailer 40-50 k€. The research costs on other softening pellets will be much smaller, most is known. For other materials new research is needed, the drying process is evidently dependent on the material that must be dried.

Environmental impact

The obvious hypothesis is that this impact is positive: high grade application become possible and almost no extra resources (like fossil fuels) are needed.

Main risks are:

  • The truck must be able to drive (and dry) 5 days a week. Not fully booked, the costs will rise;
  • At the beginning, the process will start with one truck. If this truck fails, there is no backup;
  • The pellets may differ in grain size. Size distribution has an impact on the drying process (the smaller they are, the more difficult it is to dry them;
  • The shorter the distance between source and destination, the shorter the time is to dry the pellets. If the distance is too short, the pellets will be dried as the truck stops with warmth from an aggregate. Still financial valid, but less on the environmental aspects.

Reststoffenunie

Drinking water sector established RU as a shared service centre for the sector to ‘market’ the residuals. Combining knowledge, buying- and selling-power and innovation was the main reason to work together. The moment the residuals leave the production site, RU becomes owner of these materials.

Energy positive wastewater treatment at WWTP Strass, Austria


FACTSHEET

Country Austria
Sector Municipal wastewater
Loads 90.000 - 250.000 p.e.; 43 L Biogas / p.e.

 

 

Treatment plant

WWTP Strass treats municipal wastewater with a small proportion of industrial wastewater (less than 10%). It is a rural area and the load varies due to tourism from 90.000 – 250.000 p.e. It started up in 1989 and process modifications, retrofits and control improvements were implemented to achieve energy positive wastewater treatment. Effluent requirements are 5 mg/l Ammonia –N daily average and 1 mg total P daily average; 70% N removal annual average. The plant consumes 23 kWh/PE/a. No external sludges are treated, but food waste is added as co-substrates (10% of the TS load to the digestor). The digested sludge is partly composted, partly incinerated.

Technology

Several measures and new technology implementation has resulted in the energy positive treatment:

  • Two-sludge system (high rate BOD removal followed by nitrification/denitrification) moving to mainstream deammonification.
  • Reduction of chemical costs for sludge thickening by 50% by switching from mechanical thickening to gravity thickening for biological sludge.
  • Reduction in sludge dewatering costs by 33% by switching from Ca/Fe conditioning to Polymer.
  • Reduction in energy consumption for sidestream treatment from 350 kwh/d to 196 kwh/d by implementing a novel sidestream nitrogen removal system (DEMON®).
  • Initially using primary sludge as a carbon source for sidestream treatment, since implementation of DEMON all organics are fed to digester. Total electrical energy benefit of ca. 15% by DEMON.
  • Enhanced utilization of the digester gas by converting to a state-of-the-art cogeneration unit, boosting electrical efficiency from 33% to 40% and overall usage efficiency from 2.05 to 2.30 kwh/m3 of digester gas.

Energy positive wastewater treatment at WWTP Strass, Austria

Stakeholders

There are no regulatory requirements for energy positive wastewater treatment. Cost optimization effort and benchmark comparison with other plants in Austria are done.

Trade- and craft skills of all employees involved were of high level. There was a close cooperation with research institutes, universities and other utilities.

Low revenue from electricity sales led to contract with natural gas supply company. Feeding 10 % (without co-substrates) to 80% (with co-substrates) of the electricity power back to the grid.

There is no compensation for taking over food wastes which led to reduction in co-digestion.

Barriers/bottlenecks were limited financial incentive and limited work force.

Financial impact

  • Pay-back time of all investments was 5 – 7 years.
  • 0.12 Euro/kWh for purchase from the grid;
  • 0.05 Euro/kWh sold to the grid
  • Risks were minimized by large inkind contributions.

Environmental impact

Studies were done but were not crucial for decision making.

COMPONENTS

This category shows best practices on recovery of components from water, e.g. iron sludge recovery from drinking water production and struvite production from wastewater.

HumVi – humic acids from drinking water production


FACTSHEET

Country Netherlands
Sector Drinking water
Loads 810 m3 of humic acid containing <0.25% salt and 20% humic acids 4.000 m3 of sodiumchloride solution, containing 5% NaCl

 

 

 

Vitens

Three drinking water production plants have ion exchangers to remove organic substances that cause a yellow colour in drinking water. Vitens produces 329,8 million m³ of drinking water yearly (2012). Three production plants use ground water with relatively high concentrations of fulvic/humic acids:

  • Oldeholtpade (6 Mm3/year)
  • Spannenburg (25 Mm3/year)
  • Sint Jansklooster (5 Mm3/year)
  • Since January 2014 the HumVi production plant is running at production location Spannenburg. It recovers humic acid product and sodiumchloride solution.

Technology

  • Ion exchange to remove humic acids from ground water
  • Diafiltration to produce pure humic acid stream
  • Reversed osmosis to produce salt stream that can be reused in ion exchanger

A new installation has been built at location Spannenburg. There were no changes in production location itself; it is an additional process next to main process of producing drinking water.

Stakeholders

The recovered sodiumchloride is implemented for the IEX washing step. The Humic/fulvic acid is used as soil fertilizer in the agricultural sector.

Financial impact

Processing of the waste stream lowered the operational costs to a ROI of 1.5. Time of decision process was 3 months. Building and implementation 1 year. Payback-time was less then 9 months.

Environmental impact

  • 80% reduction of logistics
  • 800 ton CO2 reduction on an annual base

Phosphorus recovery from municipal wastewater

FACTSHEET

Country USA, Oregon
Sector wastewater
Loads Durham TP 1,600 ppd Rock Creek TP 1,500 ppd

 

 

 

Clean Water Services

Clean Water Services (CWS) operates 4 treatment plants, 2 year round and 2 seasonal plants. Both the larger, year round plants have an Ostara nutrient recovery facility. CWS is a consortium of municipalities that combined into one wastewater district that provides holistic wastewater and storm water management.

Technology

Clean Water Services has two Ostara struvite precipitation reactors. The Durham facility also operates a WASSTRIP process to maximize struvite production. A WASTRIP process is being designed for the Rock Creek facility. The WASSTRIP process was invented at our utility and increases the phosphorus released from bio-P sludge which therefore increases the amount of struvite that can be harvested.

The Rock Creek facility is transitioning from chemical phosphorus removal to biological phosphorus removal to improve struvite production.

Stakeholders

Partnering with technology vendor is important, especially when a utility is an early adopter of a technology.

Involve O&M staff early to make the project successful

Consider what instrumentation will be necessary thoroughly.

Financial impact

Since the Durham Ostara facililiity was the first full scale North American installation, the project was very risky. Estimating pay back period was difficult since a market for the product didn’t exist yet. There was also very little full scale operating experience with the technology at that time.

For our Rock Creek Facility, project cost was $4.85 million dollars. We go an energy tax credit of about $1.15 million. The estimated annual revenue from the product was about $690,000 putting the estimated pay back period at around 7 years.

Environmental impact

Not estimated formally. The goal of the clean water grow product is to keep the nutrients within a local community rather than putting a product into a national supply chain with its associated carbon footprint.

Clean Water Grow

Through our agreement with Ostara, Ostara finds end users of the struvite product. Crystal Green (5-28-0 +10% Mg) is a slow release nitrogen, phosphorus and magnesium fertilizer that is used in blends by growers throughout North America. CWS is working on creating our own fertilizer product called Clean Water Grow but this is in the early stages of development.

Shared service center to market residuals


FACTSHEET

Country the Netherlands
Sector Drinking water
Loads 67 kton lime pellets and 68 kton iron sludge

 

 

 

Reststoffenunie

Drinking water sector established RU (Reststoffenunie) as a shared service centre for the sector to ‘market’ the residuals. Combining knowledge, buying- and selling-power and innovation was the main reason to work together. The moment the residuals leave the production site, RU becomes owner of these materials.

Residuals:

  • Iron sludge from ‘de-ironing’ of groundwater
  • Iron sludge from coagulation of suspended solids in surface water
  • Lime pellets from softening of drinking water

Technology

Processes are made in such a way that the residuals are produced as pure as possible and no additives or chemicals are used that have a negative impact on reuse.

Iron sludge: all drinking water companies agreed upon specifications of the sludge as it leaves the production site. These specifications are met by storing and (slightly) passively dewatering the sludge.

Lime pellets are stored in transportation silos easily accessible for trucks.

Stakeholders

Training is given to operators responsible at the production site, giving special attention to quality management. Procedures are available for:

  • Sampling
  • Transportation
  • Analysis

For new productions plants, RU is involved as a consultant looking at the residuals. At current plants, RU takes the initiative for e.g. improvement of the quality of supply chain efficiency.

Combining the residuals from the different drinking water companies was essential, giving the costumer a fair price, good quality and guarantees on the availability.

For the valorization cooperation with SME´s and research companies was important, especially to bring in practical and sometimes theoretical knowledge.

Financial impact

General: waste products are not waste anymore; status from ‘waste’ to ‘byproduct’. The ‘concept’ RU costs the water treatment companies around € 5 per ton as for the shareholder contribution. The sales revenues are exceeding these costs.

Environmental impact

The application of the residuals from the drinking water companies compensates about 15% of their carbon footprint.

Pure calcite pellets


FACTSHEET

Country the Netherlands
Sector Drinking water
Loads 15% of 67 kton softening pellets

 

 

Description

For the softening of drinking water in most cases sand is used as seeding material. This results in softening pellets (diameter about 1,2 mm) consisting of 95% or more CaCO3 and a sand core. The application of these pellets is, because of these two components, more difficult compared to limestone from a quarry. For example the grinding of the pellets is more difficult because of the different harnesses and for a vast number of applications the presence of sand is a no-go (e.g. paper or industrial deacidification).

About 15 %, this number will rise the coming years, of the Dutch softening production is now based upon calcite as seeding material. This results in ‘100% calcite’ pellets, giving more possibilities in high grade applications. The softening with calcite as seeding material is more expensive compared to the traditional softening, but the higher value of the residual more than compensates these costs.

This is not all. The 100% calcite pellets makes it possible for the sector producing their own seeding material, simply by drying, grinding and sieving the pellets. At this moment this is researched under the name ‘Dutch Calcite’, the preliminary results show this is a positive business case.

Technology

Instead of sand calcite will be used as seeding material. This results in 100% pure calcite pellets. No big changes in the softening process are required. The loading of the seeding material in the silo is altered. If the calcite seeding material has too much physical impact, the is a risk the grain distribution is changed. Calcite evidently breaks more easily than sand.

Furthermore, the seeding material can be produced from the calcite pellets by drying, grinding and sieving. In the Netherlands annually 67 kton (metric) softening pellets are produced. At this moment about 15% of this volume is produced with a calcite core. The production of calcite seeding material for the sector is estimated at a maximum of 5 kton.

Stakeholders

Legislation is a hurdle. Reusing raw materials in the drinking water process is something that is not supported by policies or regulations.

Financial impact

The production of pellets with a calcite core is estimated to be 13-17 € more expensive than rationally produced softening pellets. The added value of the pellets in sales revenue is more than these costs.

The seeding material can be produced (estimate, under research) at -25% of the current costs of seeding material.

Investments in the production process are small. A ROI is inapplicable in this case. A drying/grinding/sieving plant has an estimated payback time of 5 years or less.

Main risks are:

  • Hygiene (on the subject of producing ‘own’ seeding material;
  • Market, the sales must transcend costs. Not only now, but also in the future…

Environmental impact

The benefits are:

  • Higher end applications for the pellets, therefore reducing the use of primary chemicals
  • Production of own seeding material, preventing the import of seeding sand from (for example) Australia.

INTEGRAL

This category shows best practices which are cases that show an integrated, holistic approach. e.g. the design of a resource-conserving alternative to conventional centralized infrastructure systems.

Semizentral


FACTSHEET

Country People's Republic China, Qingdao
Sector Integrated water, energy and food
Size 12,000 people equivalent

 

 

 

Semizentral

The characteristic of SEMIZENTRAL is its integrated approach. Conventional systems focus on the strict separation of water supply, wastewater treatment, and waste treatment. In contrast, SEMIZENTRAL integrates these sectors into a holistic approach. It enables the coordination between the sectors, creating synergy effects such as energy self-sufficient operation and the reduction of greenhouse gases.

Compared to conventional infrastructure systems, the benefits are the potential for 30-40% or more reduction in water use, no external energy demand for wastewater and waste treatment, greatly reduced transport demand, around-the-clock water supply with consistent quality, and high planning security. The same applies to wastewater and waste.

Technologies

  • Greywater treatment: mechanical pretreatment, MBR (Membrane bio-reactor), chemical disinfection (chlorine, required by Chinese standards))
  • Blackwater treatment: mechanical pretreatment, MBR (Membrane bio-reactor), chemical disinfection (chlorine)
  • Sludge and foodwaste treatment: pretreatment of foodwaste (separation of nuisance substances/disinfection), thermophilic digestion, Biogas à power and heat via CHP
  • Technology provider: “standard technologies” provided by several Chinese and German companies

Stakeholders

Non potable water is reused in households. As the buildings are new, owners of apartments where not involved yet in the planning stage;
The investor (operator of the World Horticulture Exposition – WHE) was involved in the planning and influenced the water reuse purposes (using irrigation water for irrigation at the WHE)
Electric power is “clean” (carbon footprint); no quality constrains are expected; feed in the grid is still in discussion.

Driver for the City of Qingdao was the embedded energy in the water cycle. Nearby water reuse is compared to desalination much more energy efficient (< 1kWh/m³ compared to 3 to 4 kWh/m³).

Financial

Cost benefit analysis has to be done.

Risks and dependencies

  • Challenge of (missing) acceptance of water reuse within households
  • Higher Capex (but lower power demand as well as lower capex and opex for sewer because of nearby treatment)
  • Challenge of (missing) acceptance of separate biowaste collection within households, which was first intended
  • Competition with alternative (partly illegal) disposal systems for sewage sludge and foodwaste

Environmental impact

Environmental impact assessment according to Shandong/Chinese requirements had to be done. GHG reduction and social aspects will be evaluated within the next 2 years.

MBR in the water cycle and thermophilic instead of mesophilic digestion to enhance quality of biosolids.

Bottlenecks

Subsidization of water and wastewater make it difficult to implement water saving technologies and systems. Convincing was the lower embedded energy in the water cycle – SEMIZENTRAL is much more energy efficient as alternative water resources e.g. desalination. This is an incentive independent of the cost for water and energy cost

First implementation without full-scale reference makes a) the technological and b) the financial feasibility more challenging

Dealing with much more authorities (water supply, sanitation, solid waste, hygienic department, energy suppliers) compared to non-integrated approaches are a challenge.

Shared service center to market residuals


FACTSHEET

Country the Netherlands
Sector Drinking water
Loads 67 kton lime pellets and 68 kton iron sludge

 

 

 

Reststoffenunie

Drinking water sector established RU (Reststoffenunie) as a shared service centre for the sector to ‘market’ the residuals. Combining knowledge, buying- and selling-power and innovation was the main reason to work together. The moment the residuals leave the production site, RU becomes owner of these materials.

Residuals:

  • Iron sludge from ‘de-ironing’ of groundwater
  • Iron sludge from coagulation of suspended solids in surface water
  • Lime pellets from softening of drinking water

Technology

Processes are made in such a way that the residuals are produced as pure as possible and no additives or chemicals are used that have a negative impact on reuse.

Iron sludge: all drinking water companies agreed upon specifications of the sludge as it leaves the production site. These specifications are met by storing and (slightly) passively dewatering the sludge.

Lime pellets are stored in transportation silos easily accessible for trucks.

Stakeholders

Training is given to operators responsible at the production site, giving special attention to quality management. Procedures are available for:

  • Sampling
  • Transportation
  • Analysis

For new productions plants, RU is involved as a consultant looking at the residuals. At current plants, RU takes the initiative for e.g. improvement of the quality of supply chain efficiency.

Combining the residuals from the different drinking water companies was essential, giving the costumer a fair price, good quality and guarantees on the availability.

For the valorization cooperation with SME´s and research companies was important, especially to bring in practical and sometimes theoretical knowledge.

Financial impact

General: waste products are not waste anymore; status from ‘waste’ to ‘byproduct’. The ‘concept’ RU costs the water treatment companies around € 5 per ton as for the shareholder contribution. The sales revenues are exceeding these costs.

Environmental impact

The application of the residuals from the drinking water companies compensates about 15% of their carbon footprint.