Degree Programme in Environmental Engineering Vilhelmiina Harju
Final thesis
Assembling and testing of laboratory scale grey water treatment system
Supervisor Senior Lecturer Eeva‐Liisa Viskari
Commissioned by Tampere University of Applied Sciences/OPI ENEMPI project Tampere 08/2010
Tampere University of Applied Sciences
Degree Programme in Environmental Engineering
Vilhelmiina Harju
Assembling and testing of laboratory scale grey water treatment system 32pages + 1 appendix
August 2010
Supervisor: Senior Lecturer Eeva‐Liisa Viskari
Commissioned by: Tampere University of Applied Sciences/OPI ENEMPI project
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ABSTRACT
Grey water management and reuse is slowly gaining importance in the management of water resources. The benefits of well organized grey water management is that it offers a tool for coping with water scarcity and reduces the amount of pollution to enter the hydrological cycle. Grey water management aims on using treated grey water in applications which do not require drinking water quality. These non‐potable reuse applications include industrial processes, irrigation, toilet flushing and laundry washing depending on the technologies utilised in the treatment process.
This thesis concentrates on building up a laboratory scale grey water treatment system. The laboratory scale grey water treatment system was set up to the facilities of Tampere University of Applied Sciences. The aim of the thesis was to build the system and to test the flow of water within the system. Thus the thesis contains a description of the whole process of setting up and testing the laboratory scale grey water treatment system.
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Key words grey water, recycling, reuse, sand filter, waste water management
Tampere University of Applied Sciences
Degree Programme in Environmental Engineering
Vilhelmiina Harju
Laboratoriomittakaavan harmaan veden käsittelyjärjestelmän kokoonpano ja testaus
32 sivua + 1 liite
Elokuu 2010
Ohjaaja: Lehtori Eeva‐Liisa Viskari
Toimeksiantaja: Tampereen Ammattikorkeakoulu/ OPI ENEMPI‐projekti ______________________________________________________________________
TIIVISTELMÄ
Harmaan veden käsittely ja kierrätys ovat vaihtoehtoinen jäteveden käsittely menetelmä joka on hiljattain herättänyt runsaasti kiinnostusta. Hyvin suunnitellun harmaa vesien kierrätysjärjestelmän hyötyjä ovat esimerkiksi, että se tarjoaa keinon selviytyä alueilla joissa on pulaa vedestä ja vähentää saasteiden pääsyä
vedenkiertokulkuun. Harmaa veden käsittelyn tavoitteena on hyödyntää puhdistettua vettä kohteissa, joissa ei tarvitse juomakelpoista vettä. Näihin vaihtoehtoihin kuuluu esimerkiksi teolliset prosessit, keinokastelu, wc:n huuhtelu, pyykin pesu jne. riippuen kierrätysjärjestelmässä käytetystä teknologista ja sen tasosta.
Tämän lopputyö tarkoitus on kuvata ja dokumentoida laboratoriomittakaavan käsittelyjärjestelmän rakentamista. Harmaan veden kierrätysjärjestelmä koottiin Tampereen Ammattikorkeakoulun tiloihin. Lopputyön tavoitteena oli rakentaa ja testata harmaiden vesien käsittelyjärjestelmää ja kuvata prosessi.
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Avainsanat harmaa vesi, kierrätys, uudelleenkäyttö hiekka suodation, jäteveden käsittely
Foreword
Writing the thesis has been challenging and interesting process. Issues related to water have always interested me therefore I was happy to get a topic related to grey water treatment. I want to give thanks for Eeva‐Liisa Viskari for offering me this thesis topic and giving guidance during the thesis writing. I also want to thank the people working in the laboratory during summer 2010. I really appreciate the assistance and
suggestions I received for assembling and testing the grey water treatment system.
Finally I would to thank my family for supporting me during my studies. Also special thanks belong to my fellow environmental engineering students for the supportive atmosphere and memorable moments during four years of studying together in TAMK.
Tampere August 2010
Vilhelmiina Harju
Table of Contents
1 Introduction ... 6
2 Grey water management ... 7
2.1 Principles of grey water management ... 7
2.2 Definition of grey water ... 8
2.3 Grey water treatment through sand filtration ... 9
2.4 Reuse of grey water ... 10
3 Characteristics of grey water treatment system ... 11
3.1 Composition of grey water ... 11
3.1.1 Quantity of grey water ... 11
3.1.2 Quality of grey water ... 13
3.2 Operational characteristics ... 14
3.2.1 Components and materials of the system ... 14
3.2.2 Hydraulic retention time and hydraulic loading rate ... 15
4 Components of the grey water treament system ... 16
4.1 Description of the vessels and operation principles ... 16
4.2 The dimensions of the components ... 19
4.3 Filter material ... 21
5 Costs of the treatment system ... 23
6 Assembly and testing of the treatment system ... 24
7 Results ... 28
8 Discussion and conclusion ... 29
References ... 31
Appendices ... 33
Appendix 1: Tender for the treatment system ... 33
1 Introduction
Water is moves around in the hydrologic cycle continuously. The distribution of water varies between locations. Some have plenty of it while others have very little. What is common to all places is that water is vital for life. Our bodies need at least two litres of water daily. We also need water for other purposes such as washing, cooking,
cultivating etc. We have learned to utilize different states of water cycle to collect water for our purposes, for example rainwater harvesting, ground and surface water collection and springs. The water we utilize does not disappear. It is released to the cycle as wastewater. Since water is a good solvent the wastewater can contain various pollutants. Therefore it is essential to clean the water before discharging in order to secure clean water for future.
Grey water is slowly gaining importance in the management of water resources. The benefits of well organized grey water management is that it offers a tool for coping with water scarcity and reduces the amount of pollution to enter the hydrological cycle. Grey water is the wastewater from bath, laundry and kitchen. It excludes the toilet wastewater. Grey water contains less contaminant than toilet wastewater which makes it easier for recycling. Poor grey water management is usually linked to
environmental degradation and serious health risks. But during recent years grey water has been considered as a valuable resource rather than just waste.
The aim of the thesis is to describe the process of building a laboratory scale grey water treatment system. The thesis topic was suggested to me by Eeva‐Liisa Viskari.
The topic is continuing the work of Shannon O’Neill. His thesis topic was “Planning of laboratory scale grey water recycling system”. This work aims to implement the plan and built the laboratory scale grey water treatment system using the suggestions made by Shannon O’Neill in his thesis.
The grey water treatment system will be placed to the green house of Tampere University of Applied Sciences (TAMK) and its purpose is to demonstrate one type of grey water treatment system. The purified water can be used to irrigate the plants grown in the green house.
2 Grey water management
Water scarcity, poor water quality and water related disasters are three challenges related to current and future water resources. In mitigating these challenges grey water management can offer a viable solution. By reusing treated grey water the pollution of freshwater resources can be reduced since the contaminants are removed before discharge to water resources. This leads to the fact that also the quality of water will be improved. (Morel & Diener 2006, 1).
2.1 Principles of grey water management
As with any source there are two principles related to economy of water use. Using and wasting less combined with finding and making available alternative sources of water. Grey water management can provide an alternative source of water
(Sutherland 2008, 18). Grey water management aims on using treated grey water in applications which do not require drinking water quality. These non‐potable reuse applications include industrial processes, irrigation, toilet flushing and laundry washing depending on the technologies utilised in the treatment process. (fbr 2007, 2)
In areas where there is scarcity of water for instance arid, semi‐arid regions and highly populated areas recycling and reuse of water is a viable mean to cope with the water shortage. (Ahmad & EL‐Dessouky 2008, 973). Also in areas that are rich in water resources water recycling is important, because it aims to sustainable living. It reduces the amount of fresh water consumption and wastewater production and in addition reduces the water bill (fbr 2007, 3). Below in figure 1 there is an image of one type of grey water recycling model to a private house.
Figure 1. Simple grey water recycling model for a private house (Flotender 2010)
If grey water is discharge without any treatment or if reuse or recycling methods are inappropriate the contaminants can cause harmful impact on human health, soil and groundwater quality. Therefore appropriate grey water treatment before the
discharge of wastewater could dramatically reduce water pollution. (Morel & Diener 2006, 5)
2.2Definition of grey water
Grey water can be defined as the wastewater generated from baths, showers, hand basins, washing machines and dishwashers, laundries and kitchen sinks. This means that the wastewater from toilets is excluded when considering the sources of
wastewater of a household. The characteristics of the grey water depend on facts such as the cultural habits, living standards, household demography type of household chemicals used etc. Grey water contains micro‐organisms, chemical contaminants (e.g. nutrients and salts) and physical contaminants (e.g. dirt and sand). (Morel &
Diener 2006, 5)
2.3 Grey water treatment through sand filtration
Grey water must be purified in order to be safe for reuse. One of the options is to run the water through sand filtration. Sand of filtration depends on biofilms. In the filtration process, biological degradation of suspended and dissolved organic matter takes place when grey water passes through the filter material which provides a surface for bacterial growth. The bacteria fixed on the filter media breaks down the suspended and dissolved organic matter in grey water. (Morel & Diener 2006, 28) There are several factors effecting on the filtration. The treatment efficiency of the sand filter depends on the media used, temperature, the characteristics of the wastewater, hydraulic and organic loads. The particle size has the biggest impact on the treatment efficiency and also to reliability and durability of the system. The biggest operational problem that might occur is clogging phenomena caused by excess biofilm development and surface deposit. (Rolland et al. 2009, 998‐999)
The method used in this study is anaerobic filtration. The grey water flows though the filter material from bottom to up. The method is also called up‐flow sand filtration or sometimes also referred as slow filtration. In the process the grey water comes in contact with the biomass of the filter and is subjected to anaerobic degradation.
(Morel & Diener 2006, 28)
As mentioned earlier on the surface of the filter material biofilm will be slowly formed.
This is a good phenomenon because the layer will help in the purification process.
When the treatment efficiency drops too low the filter layers must be cleaned from the biofilm. In slow filtering it might not be necessary to clean the filters by
backwashing with water. An alternative method is to clean only the surfaces of the layers from the biofilm. When the filter layer is reduce 30 % new sand need to be added. (Kujala‐Räty, Mattila & Santala 2008, 51‐52)
2.4 Reuse of grey water
There are several options for how to reuse or discharge treated grey water. One option is to reuse grey water in agricultural industry for example irrigation. Also treated grey water can be used in household for applications that do not require drinking water quality, for example toilet flushing or washing laundry. In figure 2 below there is a flow diagram which illustrates reuse of grey water in a private house. Third option is to use grey water can be industrial processes which also do not require the standard of purity of drinking water. (fbr 2007, 2)
Figure 2. Average partial water flows (litres per inhabitant and day) for private
households in new buildings and sanitary rehabilitated buildings (fbr 2005, 11)
In case where reuse is not an option treated grey water can be discharge to nature. For instance it can be discharge into surface water (river, lake, pond, sea). Another option is infiltration. Grey water can be infiltrated into soil which creates possibility of
groundwater recharge. The suitable option selected either reuse, discharge or infiltration depends strongly on the local situation and possibilities (Morel & Diener 2006, 40).
3 Characteristics of grey water treatment system
The purpose of the grey water treatment systems is to collect, store and reduce the organic and hygienic load of grey water to the standard of being safe for reuse (fbr 2005, 16). Also there are some factors affecting on the choice of technology used in the grey water treatment system. It depends on:
• Planned site
• Available space
• User needs
• Investment and maintenance costs
There are several ways to treat grey water to the standard of being safe for reuse.
Grey water treatment system can vary from simple, low‐cost devices that purify water for applications such as toilet flushing or irrigation in garden, to highly complex and more expensive systems that include sedimentation tanks, bioreactors and disinfection units. (fbr 2007, 5). This thesis is aiming on the system that is simple and low‐cost.
3.1 Composition of grey water
3.1.1 Quantity of grey water
Grey water makes about of 50‐80 % of wastewater generated by the households. If a dry toilet is also used in the household, then grey water makes 100% of wastewater generated. The largest share of grey water is produced by bathroom. Grey water generated from kitchen and laundry has a smaller fraction. (fbr 2007, 1). In figure 3 there is an example of the percentages of wastewater produced by the sources.
Figure 3. Example of the percentages of wastewater produced by the different sources.
(Lehr, Keeley & Lehr 2005, 16)
The typical volume of grey water from a household varies from 90 to 120 l/p/d (litres per day). The volume depends on factors such as lifestyle, living standards, customs and habits, water installations and the degree of water abundances. The volume of grey water in low income countries with water shortage and simple forms of water supply can be as low as 20 to 30 l/p/d. (Fangyue et al. 2009, 3440)
3.1.2 Quality of grey water
As mentioned earlier grey water can be categorized by its source. These are kitchen, bathroom and laundry. Each of these sources produces grey water with slightly different composition. These compositions are collated in table 1.
Table 1. The composition of grey water originating from kitchen, bathroom and laundry. (Morel & Diener 2006, 5)
Kitchen Kitchen grey water contains food residues, high amounts of oil and fat, including dishwashing detergents. In addition, it occasionally contains drain cleaners and bleach. Kitchen greywater is high in nutrients and suspended solids.
Dishwasher grey water may be very alkaline (due to builders), show high suspended solids and salt concentrations.
Bathroom Bathroom grey water is regarded as the least contaminated grey water source within a household. It contains soaps, shampoos, toothpaste, and other body care products.
Bathroom grey water also contains shaving waste, skin, hair, body‐fats, lint, and traces of urine and faeces. Grey water originating from shower and bath may thus be contaminated with pathogenic microorganisms.
Laundry Laundry grey water contains high concentrations of chemicals from soap powders (such as sodium, phosphorous, surfactants, and nitrogen) as well as bleaches, suspended solids and possibly oils, paints, solvents, and non‐biodegradable fibers from clothing.
Laundry grey water can contain high amounts of pathogens when nappies are washed.
When grey water is just produced it does not usually have any unpleasant odour.
When compared with black water, grey water has a comparatively higher temperature and readily degradable pollutants. Thus, it needs to be immediately treated after collection. If untreated grey water is stored for long periods, oxygen deficient conditions will develop and scum will be formed which can float or sink in the collection tank. Also studies indicate that bacterial population also increases with longer storage time. (Lehr et al. 2005, 16) Typical grey water pollutant concentrations from different sources are shown in table 2.
Table 2. Average Pollutant Concentration in Gray Water Measured in a Residence Hall (Lehr et al. 2005, 17)
Bath/
Shower
Washbasin Washing Machine Laundry and Dishwashing
BOD (mg/L) 216 252 472 110
COD (mg/L) 424 433 725 –
Phosphate as P (mg/L) 1.63 45.5 101 –
Ammonia as N (mg/L) 1.56 0.53 10.7 –
Turbidity (NTU) 92 102 108 148
Total solids (mg/L) 631 558 658 538
pH 7.6 8.1 8.1 7.8
3.2 Operational characteristics
3.2.1 Components and materials of the system
There are several issues to take into considerations when choosing the components and material. The requirements depend on the type on treatment system one wants to build, but some of them are common for all types of treatment system. For instance, the pipes and fittings of the device, which are in contact with the untreated grey water, have to be designed is such way that there is no sharp edges or other forms creating blockage. Hair is good example of causing operational problems if gets stuck in the system due to sharp edges. Also all mechanical equipment (pumps, filters etc.) have to be easily accessible and removable in case of repair, maintenance and cleaning works. (fbr 2005, 17)
Additional requirements for the pipes is that the they should be installed so that they are straight without necks or depressions and with a gradient of at least 0,5 %. This will prevent the clogging from grease (Ecosanres).
The material selection has to be also functional. According to the study of Ahmed Jamil et al. if the treated water is high in alkalinity stainless steel might increase the iron content of the treated water. Thus it is better to use plastic in building the system to avoid the risk of corrosion which leads to increase in iron content of the treated water.
The choice of the sand is important factor to take into consideration as well. The choice has an impact on the water and oxygen transfer into the filter and the bio film growth into the media. As a consequence the pollutant removal rate differs in
depending on the composition of the filter material because of the medium prosperities such as pore size and permeability. (L. Rolland et al 2009, 1000)
3.2.2 Hydraulic retention time and hydraulic loading rate
Hydraulic retention time (HRT) is expresses the amount of time water drop stay in the biological reactor. The HRT can be calculated volume of the tank divided by the daily flow. The HRT is important parameter because it defines the contact time between the water that contains chemicals and solid particles with the biomass in which is
composed of microorganisms utilizing substances in the water for growth. (Water Environment Federation 2005, 117) Common HRT in up‐flow sand filters are 0,5 – 1,5 days. ( Morel & Diener 2006, 29)
Another important parameter is hydraulic loading rate (HLR). HLR expresses the amount of water applied to the process. The rate can be determined by the knowing the volume of the system and the flow rate of the soluble compound. The maximum hydraulic loading rate is suggested to be 2,8 m/d (volume per unit time). ( Morel &
Diener 2006, 29)
4 Components of the grey water treament system
The components of the system were ordered from plastic product manufacturing company in Tampere. The company was provided with the operational principles and a list of needed components with dimensions. The filter material was bought from a department store in Tampere.
4.1 Description of the vessels and operation principles
The main components of the grey water system are pump, two vessels placed on top of each other, four smaller vessels, grate separator and catchment basin. Figure 4 illustrates the whole system. The flow of water starts from the vessels on the left side and continues until the catchment basin the on the right. The four smaller containers will be place in between. All components are connected with hoses. In the thesis of Shannon O’Neill there is a more detailed description of the layout of the system.
Figure 4. The grey water treatment system
Pump will be pumping water through a hose to header vessel. As seen in figure 5 the inlet is the side of the header vessel. The flow of the water is illustrated with the arrows. At the bottom of the header vessel there is a hose that leads to the bottom of the lower vessel. This hose transports untreated grey water to the lower vessel. The water goes under a grate separator and from there continues flow upwards to the top of the lower vessel where there is an outlet connected to a hose.
Inlet
Outlet
Figure 5. The grey water treatment vessels
The grate separator is located at the high of 5 cm from the bottom of the lower vessel.
It is 10 mm thick and has holes of size of 3 mm with 6 mm distance from each other.
The purpose of the grate separator is to keep the filter material up so that the water can flow freely to the bottom and prevents possible blockages the bottom.
Figure 6. Grate separator
The water filtrates slowly though the filter material which will place on top of the grate separator to the top of the vessel. Layers of stones, grave and sand will be used. During the penetration through the filter material the water gets purified.
From the top it continues through a hose to smaller containers as can be seen in figure 7. There is a component to spread the water into two containers. This component has one inlet and two outlets. The smaller containers can be attached with hoses to another two smaller containers or to a catchment basin.
The water coming out from the lower vessel is can be used for watering plants. The four small containers can be used for planting plants that has the characteristics of purifying water.
Figure 7. The smaller containers and catchment basin
4.2 The dimensions of the components
• The header vessel is 500 x 300 x 400 mm.
There is a round inlet with diameter of 30 mm.
• The lower vessel is a slightly higher.
The dimensions are 500 x 300 x 600 mm.
It has a round outlet with diameter of 30 mm.
• The hose connecting the vessels is 570 mm long leaving 30 mm space for water to flow to the bottom of the lower vessel.
The diameter of the hose is 400 mm.
Figure 8. Purification vessels
• At the high of 50 mm there is a grate separator. The thickness of the separator is 10 mm and it has holes size of 3 mm at the distance of 6 mm.
Figure 9. Grate separator
• The size of the small containers is 300 x 150 x 150 mm and they have inlets and outlets to connect the containers to each other.
Their diameter is also 30 mm and they are 30 mm up from the bottoms of the containers.
Figure 10. Smaller vessels
• The catchment basin has dimensions of 800x600x400mm and has two inlets with diameter of 30 mm at the height of 30 mm from the bottom and an outlet with same diameter (30 mm) near the top of the container.
Figure 11. Catchment basin
4.3 Filter material
Three different types of filter material were selected. Stones that have average size of 20‐40 mm, gravel average size of 8‐12 mm and fine sand average size of 0‐2mm. The materials are presented in figure 12.
Figure 12. Filter material
The stones size of 20‐40 mm was placed at the bottom layer to prevent material losses and holes blockage. The height of layer for testing was set to be 8 cm. The second layer was filled with gravel average size of 8‐12 mm until the layer had a high of 16 cm. A layer of fine sand average size of 0‐2mm was poured 20 cm on the top.
Figure 13. The layers of filter material
In between the layers a filter cloth was placed. The reason for this is that the filter cloth prevents the filter materials from mixing and therefore the layers are easier removed from the vessel. The testing at this stage is only done with tap water so the filter cloth does not distort the testing. The layers can be seen in figure 13.
Approximately a space of 10 cm was left on the top to maintain the water level and to provide smooth flow of water out of the vessel.
5 Costs of the treatment system
The costs of the treatment system and the filter material are collated in table 3.
Majority of the cost came from the parts treatment system and the pump. The parts of the treatment system cost all together 788,12 €. The price contains the material used, charge of the labour and taxes. Additional cost for the treatment system came from the support bands of the vessel which caused together 73,80 €. The price of the pump was 805,20 €. The table 3 shows only the total price of the system, but the breakdown of costs of all the parts can be seen in appendix (1) attached in the end.
The gravel and the sand where bought in a 25 kg sack and stones in sack of 20 kg.
Gravel, sand and stones where bought two sacks of each which totals six sacks with a price of 58,30 €.
Table. 3. Cost of the treatment system
Component Price Summing up
The parts of the treatment system
646€, +alv. 22%.
788,12 €
Supporting bands 73,80 € 73,80 €
The filter material 20 kg sack of stones (20‐40 mm) á 9,95 €
25 kg sack of gravel (8‐12 mm) á 9,75 €
25 kg sack of sand (0‐2 mm) á 9,45 € ??
2 × 9,95 € = 19,90 € 2 × 9,75 € = 19,50 € 2 × 9,45 € = 18,90 € Total = 58,30
€
Pump 805,20 € 805,20 €
Total price 1725,42 €
All in all the total price of the system was 1725,42 €. The purchase of purifying plants for the small containers will later add some extra costs for the total price of the treatment system.
6 Assembly and testing of the treatment system
Testing was done with tap water which was allowed to run through the whole system.
The aim of the testing was to see that the treatment system is operating without any difficulties when the water is pump into the system.
Before starting to test all the components were installed. All the components were combined with hoses. The smaller containers were place on stairs to be higher that the catchment basins as can be seen in figure 14 in order to secure smooth flow.
Figure 14. Testing of the treatment system
The lower vessel was filled with the filter material. First problem occurring while combining the parts was with the tube connecting the two vessels. Since the tube was attached to the bottom of the upper vessel it was impossible to fill the lower vessel, because while filling there needs to be space left for the tube to go through the filter material. Therefore an extra peace of tube needed to be placed on the lower vessel while filling the filter material. After filling the lower vessel the tube attached to the upper vessel was place inside the extra piece of tube.
Tube connected
to upper vessel
Extra tube
Figure 15. Adjustment of the tubes
The second problem appeared when the filter material was placed on the lower vessel.
The grate separator started to bend due to the weight of the filter material as shown in figure 16. Therefore additional support needed to be added below the separator.
Figure 16. Adjustment of the grate separator
When all the elements were in order the water was fed to the system. First the water was fed through a hose connected with the tap in order to see if there were any leakages. While the containers where filling up they started to expand as can be seen in figure 17. When observing them the containers seemed to last although the sides were on curves. According to the manufacturer the material of the vessels will last even though there sides expand, but to be on the safe side support was added on the outer sides of the vessels (see figure 18).
Figure 17. Expansion of the lower vessel
Figure 18. Supporting band
Few of the hoses needed to be tighten up, but otherwise the water was flowing
smoothly through whole the system. The second testing was done with the pump. The pump was set to flow rate of 85 ml/min. The water was flowing well through the system. The flow rate was also measured from the outlet of the catchment basin and the measurements show that the flow rate was approximately the same 85 ml/min.
Although the stones, gravel and sand was quickly washed before setting them into the vessel the water filtered had a strong brownish colour.
7 Results
The values for flow rate, HRT and HLR can be seen in table 4. When calculating the HRT and HLR , using flow rate of 85 ml/min, the values are in the suitable. According to Morel & Diener the HRT should be between 0,5 – 1,5 days and HLR should be less than 2,8 m/d. Therefore can be concluded that flow rate of 85 ml/min is suitable for the treatment. The flow rate, HRT and HLR are only indicative and can be adjusted again when the treatment system is filled with grey water.
Table 4. Flow rate, HRT and HLR of the treatment system
Flow rate 85 ml/min
Hydraulic retention time (HRT) 0,5 d Hydraulic loading rate (HLR) 0.8 m/d
There were couple of errors in the system when assembling the treatment system.
These errors are collated in table 5 together with the improvements done. After fixing the errors the treatment system was functioning well.
Table 5. Improvements made for the treatment system.
Error Cause and problems Improvement
Tube attached to the upper vessel
Impossible to fill the lower vessel with filter material, because when filling the vessel the tube should also be attached the grate separator.
Addition of extra tube
Bending of grate separator Too heavy load on top of it Addition of support Expansion of the vessels
after filling with water
The sides of the vessels expanding
Addition of support
8 Discussion and conclusion
Although couple of problems occurred while combining the components together the system functioned well when tested with the water flow. The problems were possible to overcome therefore they did not cause any operational problems. These designing errors were left unnoticed when planning the system. While sketching the system on paper it can be difficult to master the whole system. When trying to make one part of the system work there is a chance of forgetting the effect of it on other parts of the system. Also unfamiliarity of material from which the parts were made had an effect on the planning problems.
During testing it was noticed that it could be useful to have extra outlets in the lower container and in the catchment basin. These outlets should be placed on the sides near to the bottom. They should have a stopper which could be easily opened and closed when the water needs to be emptied. The location is shown in figure 19. The black circle shows the location. This would make it easier to empty the containers for instance when there is a blockage in the vessel or water in the vessel is overflowing.
With the help of the stoppers the water could be let out fast.
Figure 19. Extra outlet to lower vessel
The efficiency of the filter material was not able to be seen since the purpose of the testing was only to see how the water flows through the system. But what can be
commented about the filter material is that the water got filtrated without difficulties.
When examined visually there were no visible blockages or compaction of sand. Also when measuring the flow rate from the start and the end of the system it was
constant. The flow rate of 85 ml/min gives also good values for the treatment system in HRT and HLR. The HRT was 0,5 d and HLR 0.8 m/d.
Since the sand created no blockage when water filtrated through it might be that the stones are not necessary in the process. The space for filter material is rather small.
Therefore using only two materials might yield better treatment efficiency. The filter layers could be made out of the gravel and sand only. The first layer would be gravel, then a layer of sand and on the top a layer of gravel again to prevent sand particles moving with the water to the outlet. In order to see if it will work, testing with grey water should be done.
All in all the study can now proceed to testing the treatment system with grey water and figuring out the best combination of the filter material.
References
Ahmad Jamil & Hisham EL‐Dessouky. 2008. Design of a modified low cost treatment system for the recycling and reuse of laundry waste water. Resources, Conservation and Recycling 52. 973‐978
Fangyue Li, Knut Whichmann & Ralf Otterpohl. 2009. Review of the technological approaches for grey water treatment and reuses. Science of the Total Environment 407. 3439‐3449.
Kujala‐Räty, Katriina, Harri Mattila & Erkki Santala.2008. Haja‐asutusaluiden vesihuolto. Hämeenlinna. Hämeen Ammattikorkeakoulu.
Lehr Jay, Jack Keeley & Janet Lehr. 2005. Water Encyclopedia. New Jersey John Wiley &
Sons, Inc.
Morel A.& Diener S. 2006. Greywater Management in Low and Middle‐Income countries, Review of different treatment systems for households or neighbourhoods.
Dübendorf, Switzerland. Swiss Federal Institute of Aquatic Science and Technology (Eawag). Also available at:
http://www.eawag.ch/organisation/abteilungen/sandec/schwerpunkte/ewm/projects /project_greywater
O’Neill, Shannon. 2009. Planning of laboratory scale water recycling systems.
Bachelor’s thesis. Tampere University of Applied Sciences. Department of Environmental Engineering. Tampere.
Rolland L, P. Molle, A Liénard, F. Bouteldja & A. Grasmick. 2009. Influence of the physical and mechanical characteristics of sands on the hydraulic and biological behaviours of sand filters. Desalination 248. 998‐1007.
Water Environment Federation. 2005. Biological Nutrient Removal (BNR) Operation in Wastewater Treatment Plants. McGraw‐Hill Professional Publishing.
Sutherland, Ken. 2008. Wastewater filtration: Future for grey water recycling. Filtration + Separation April 2008. 18‐21.
Online references
Ecosanres 2008. Introduction to Greywater Management. Referred to 14.4.2010 http://www.ecosanres.org/pdf_files/ESR‐factsheet‐08.pdf
fbr. Association for Rainwater Harvesting and Water Utilisation. 2007. Grey water recycling and reuse. Referred to 15.7.2010.
http://www.fbr.de/fileadmin/user_upload/files/Englische_Seite/Greywater_Recycling _Introduction.pdf
fbr. Association for Rainwater Harvesting and Water Utilisation. 2005. Information Sheet H 201. Greywater Recycling. Referred to 15.7.2010.
http://www.fbr.de/fileadmin/user_upload/files/Englische_Seite/H201_fbr‐
Information_Sheet_Greywater‐Recycling_neu.pdf
Flotender. 2010. Fotender Grey water Recycling systems. Referred to 15.7.2010.
http://www.flotender.com/pages/greywater‐recycling‐systems‐with‐drip‐irrigation
All photos taken by Vilhelmiina Harju
Appendices
Appendix 1: Tender for the treatment system
TARJOUS
Tilaaja: 19.5.2010
Pirkanmaan Ammattikorkeakoulu Oy Eeva-Liisa Viskari
Kuntokatu 3 33520 Tampere Tuote:
Harmaiden vesien puhdistusjärjestelmän osat
Materiaalit ja mitat:
Kirkas 5mm akryyli, mitat kuvien mukaan.
Toimitus:
2-3 viikkoa tilauksesta, vapaasti varastossamme.
Maksuehdot:
21 pv netto
Viivästyskorko 11%
Hinta:
Ylempi astia 500x300x400mm, 40/30x570mm putkella joka liimattu kiinteästi astian pohjaan, 30mm sisääntuloaukko yläosassa
á 120€, + alv. 22%.
Alempi astia 500x300x600mm, 30mm ulostuloaukko yläosassa á 130€, + alv. 22%.
Reikälevy 10mm kirkas akryyli 489x289mm, 3mm reiät 6mm välein, reikiä yht. 1728kpl
á 80€, + alv. 22%.
PVC-letkua n. 30mm halkaisija 4 metriä á 7€, + alv. 22%.
Pienet astiat 300x150x150mm 4 kpl, sisään- ja ulostuloaukot á 37€, + alv. 22%.
Valuma-allas 800x600x400mm, sisään- ja ulostuloaukot á 140€, + alv. 22%.
Yht. 646€, +alv. 22%.
