Development of an innovative wastewater reuse plant for the RINEW project

Increasingly, harbour activities in the harbour of Rotterdam are moving west towards the Northsea (Maasvlakte I & II). This impoverishes harbour areas close to Rotterdam like the Stadshavens area. The municipality of Rotterdam is trying to revitalize these areas by transforming them into sustainable living and working communities. Evides N.V. is participating in this by developing an innovative wastewater reuse plant which will reuse the wastewater from the Stadshavens area by treating it to demi-water standards, while also recovering nutrients and energy. The objective of the research described in this thesis is to develop several sustainable and innovative treatment scenarios for the wastewater reuse plant, test relevant innovative technologies on lab scale and present a conceptual design of the wastewater reuse plant. Conventional wastewater treatment plants treat the wastewater under both aerobic and anaerobic conditions. Especially the aeration needed for aerobic treatment has a high energy consumption. With the development of new treatment techniques like ceramic nanofiltration and forward osmosis it is now possible to replace the aerobic treatment used in conventional wastewater treatment plants by these technologies. This saves energy and gives a smaller installation footprint (no settling phases are necessary). Four scenarios were developed, two using combined collection of wastewater, while the other two have a separate collection of grey water (from washing) and black water (from toilets). One of the combined collection scenarios and one of the separate collection scenarios uses ceramic nanofiltration (CNF) as a first treatment step, while the other two use forward osmosis (FO) as a first treatment step. After the first treatment step, the water quality is sufficient to produce demi-water by using the reverse osmosis process (RO). In the separate collection scenarios, the grey water is treated similarly to the wastewater treated in the combined collection scenarios. Nutrients and energy are recovered from the reject water of the CNF and FO processes by applying anaerobic digestion in the form of a UASB reactor. This process produces sludge and biogas from the biological material in the wastewater. After this step, magnesium ammonium phosphate precipitation and SHARON®-Anammox® processes are applied to recover orthophosphate and ammonium from the wastewater. With the separate collection scenarios, the black water is treated similarly to the concentrate water treatment in the combined collection scenarios. After comparing the scenarios based on energy consumption, demi-water production and demi-water quality, it was chosen to apply separate collection of wastewater , using CNF as a primary treatment step. The CNF process was tested on lab scale to review its performance when treating either raw wastewater or grey wastewater. Results indicated a better permeate quality and reject composition when treating grey water, but more fouling was observed, compared to raw wastewater. However, it is estimated this is controllable by applying regular backwashing and chemical cleaning. This research has shown that membrane processes can be used as a viable replacement for the aerobic processes which are used in conventional wastewater treatment plants. By using membrane processes instead of aerobic processes, less energy is consumed, while still achieving reliable effluents and reuse products. Based on the research a conceptual design of the wastewater treatment plant was made which consisted of a building which contains all treatment processes except the grey and black wastewater buffers, the demi-water storage and the digestion process tanks which are located outside of the building.

Subject

wastewater
reuse
forward osmosis
ceramic nanofiltration
demi-water
design
RINEW

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master thesis

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