TREATMENT OF HOUSEHOLD GRAY WATER WITH INTERMITENT SAND FILTERS

Prévia do material em texto

2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
TREATMENT OF HOUSEHOLD GRAY WATER WITH INTERMITENT SAND 
FILTERS 
by 
Caio Cesar Barbosa de Siqueira 
Laryssa Barbosa Fernandes 
Tais Carolina de Oliveira Alcantara 
Macon, GA 
2015 
 
Approved: 
 Date: 
Philip T. McCreanor, Ph.D., Professor, Director of Engineering Honors 
 
Abstract 
This study presents the effectiveness gray water treatment utilizing ISFs for reuse in 
irrigation process. Six columns divided in two groups, group 1 with same diameters but different 
loading rates and group 2 with different diameters but same loading rates, performed a series of 
analysis and tests as BOD5 and COD analysis. According to EPA standards BOD values for 
irrigation process are 25 mg/l. The BOD results of the two groups showed values close to zero 
and a removal efficiency between 98% and 100%. 
 
Keywords 
Gray Water, grey water, recycling, sand filter. 
 
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
 
Introduction 
Water is a patrimony of humanity and indispensable for the existence of life. However, 
the availability of water for use is running out due to the inordinate use, this context reveals the 
importance of water conservation. One of the ways existing alternatives for conservation of 
water is reuse. 
One of the main types of wastewater that has been growing amount of research, 
treatment, recycling and reuse is the grey water. Grey water is defined as the urban wastewater 
that includes water from baths, showers, hand basins, washing machines, dishwashers and 
kitchen sinks, but excludes streams from toilets. Some authors exclude kitchen wastewater from 
the other grey water streams. Grey water constitutes 50–80% of the total household 
wastewater.(Li et al., 2009). 
Grey water has different technologies types for the treatment. Intermittent sand filters 
(ISF) are a technology that is gaining more notoriety in the treatment of grey water due to the 
low cost and a mechanically simple alternative. 
 
Literature Review 
B. Jefferson et al. (2003) defined gray water as urban wastewater without any input from 
toilets and so generally includes sources from baths, showers, hand basins, washing machines, 
dishwashers and kitchen sinks. Also, gray water is responsible for 50-80% of the total 
wastewater generated in a residence and is distinct from black water in the amount and 
composition of its chemical and biological contaminants (Ukpong et al. 2012). E. Eriksson et al 
(2001) indicates that the knowledge about grey wastewater is limited, being necessary to expand 
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
the study in this area, bringing more information about measurements of heavy metals, since the 
studies, in general, focus on the BOD, COD, nutrients and some micro-organisms. 
 
Nowadays many technologies has been applied in gray water treatment, include physical, 
chemical, and biological systems, an efficient example that includes the three techniques listed is 
the use of intermittent sand filters (ISF). According to Environmental Protection Agency (EPA) 
the biological processes have the most important role in sand filters, since the filters promote the 
growth of bacteria responsible for treating gray water. Another efficient technology to treat gray 
water is constructed wetland, a recycled vertical flow constructed wetland showed good 
treatment performance, with a BOD5 reduction from 466 mg/l in the influent to 0.7 mg/l in the 
effluent, Gross et al. (2007). In addition, another promising technology is the membrane 
bioreactor technology, however it has a high investment cost. The study made by C Merz et al. 
(2006) showed that this treatment is efficient to treat gray water with low COD value and low 
nutrient content. 
 
According to Nolde and Dott (1991) the major difficult for gray treatment is the large 
variation in its composition. For instance, data collected indicates that COD values vary from 40 
to 371 mg/l between sites. Knowing this difference Li et al. (2009) explain that gray water 
should be equalized in a storage tank to cope with the variability in influent, in order to make the 
influent more stable for the treatment, and the larger particles, hair, oil and grease shall be 
removed before feeding it into the followed treatment processes. According to Pinto et al (2009) 
the final effects of the gray water reuse to irrigation were not significant on the plant biomass 
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
and in the total N and total P contents of soil after the plant harvest, but the pH in the soil 
increased. 
 
Objective 
The design of an Intermittent Sand Filter (ISF) requires a criterion for the particle size of 
the sand bed, the flow rate according to the surface area, and the diameter of the filter. Previous 
studies identified a #20 sand, which corresponds to approximately 0.84mm in diameter, as the 
most promising media for ISFs treating gray water. The objective of this project is to determine 
an appropriate field rate for a 30” deep, #20 sand filter. 
 
Methodology 
The experiment was conducted using two groups of ISFs. The first group (Figure 1) has 
three ISFs with same diameter and different loading rates. Each column was constructed using a 
4’’ diameter PVC Pipe, and filled sequentially from the bottom with 3” of pea gravel, 30” of #20 
sand, and 2” of pea gravel. These columns were loaded at rates of 0.6, 0.9, 1.2 and 1(gpd/ft2). 
The second group (Figure 2) has three ISFs with different diameters and same loading rates 
(1gpd/ft2). These columns were constructed using 3’’,4” and 6” diameter PVC Pipe, each column 
was filled sequentially from the bottom with 3” of pea gravel, 30” of #20 sand, and 2” of pea 
gravel. 
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
 
Figure 1. ISFs columns with same diameters – Group 1 
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
 
Figure 2. ISFs columns with different diameters (4”,6” and 3” from left to right) – Group 2 
 
Created according to the NSF 350 Standards for Wastewater Treatment was created a 
synthetic grey water, used to feed the columns daily. The components of stock solution are 
shown below in the Table 1. 
 
Table 1. Stock Solution Components 
Components NSF/ANSI amount/100L 
Body Wash 30 g 
Toothpaste 3 g 
Deodorant 2 g 
Shampoo 19 g 
Conditioner 21 g 
Lactic Acid 3 g 
Bath Cleaner 10 g 
Liquid Hand Soap 23 g 
Liquid Laundry Detergent 40 mL 
Liquid Fabric with Softener 21 mL 
Na2SO4 4 g 
NaHCO3 2 g 
Na2HPO4 4 g 
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
 
The synthetic gray water solution was create daily using a stock chemical solution that 
diluted with tap water and secondary effluent, from the LowerPoplar Wastewater Treatment 
Plant in Macon, Georgia as indicated in Table 2. 
Table 2. Dilution Volumes 
Dilution Volumes 
Stock Solution 133 mL 
Tap Water 2317 mL 
Secondary Effluent 50 mL 
 
The performance of the columns was evaluated based by monitoring influent and effluent 
COD and BOD5. This test is useful to measure the amount of chemicals present in the water that 
can be oxidized. The COD test was done every three days for columns achieved stability. The 
Biochemical Oxygen Demand (BOD) test measure only the amount of organic matter available 
bacteria for oxidize. In other words, it is a measure of the amount of food available bacteria to 
consume to. The COD result will be always greater than the BOD result and can be used as a 
guide for BOD dilution. 
 
Experimental Procedures 
Column loading 
The first group of ISFs columns, same diameters, were loaded daily rates at 1.2 gal/ft2, 
0.9 gal/ft2, and 0.6 gal/ft2. Based on calculations through the loading rates each column received 
a different amount of influent, 409 mL, 307 mL and 205 mL for the 1.2, 0.9 and 0.6 gdp/ft2 
columns, respectively. The second group of ISFs columns, had the same loading rate but 
different diameters of 3”, 4”, and 6” respectively, were loaded daily at 1gpd/ft2. The volumetric 
loading was 195, 335 and 760 mL for the 3”,4” and 6” columns, respectively. 
 
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
COD Analysis 
The COD analysis performed according to Hach DR 2800, was conducted every third 
day. In this study, one blank and 2 vials for influent analysis with high range measurement and 
one blank and 6 vials for effluent with ultra low range measurement. The blank was aerated with 
2mL of deionized water. After preparation, the vials were placed in Hach COD digester where 
they will remain for 2 hours. After this period, they were removed and allowed to return. The 
vials were cleaned with Kim wipe and then read through Hach DR 2800. Finally, each COD 
value obtained is stored in a spreadsheet in Excel to determine a new BOD5 volume. 
 
BOD5 Analysis 
The BOD5 dilution factor was determined by made using COD values as guideline. 
BOD5 analysis was conducted on influent. [During this 5-days the samples are stored at 20 
degrees Celsius]. Generally, a total of 24 bottles are made for day which constitutes of 3 bottles 
each for influent, blank and six columns. The influent bottle consists of synthetic gray water, 
which is prepared everyday. Blank bottle consists of BOD nutrient water and the sample bottles 
consist of a certain amount of sample, defined by the COD value, and the remaining 300 ml with 
BOD nutrient water. A Hach DO model HQ440d was used to measure the initial DO in each 
bottle. The data will be saved in an Excel spreadsheet and then the bottles are stored. This 
equation 
(𝐼𝑛𝑖𝑐𝑖𝑎𝑙 𝐷𝑜−𝐷𝑜5)
(𝑆𝑎𝑚𝑝𝑙𝑒 𝑉𝑜𝑙𝑢𝑚𝑒)/(𝐵𝑜𝑡𝑡𝑙𝑒 𝑉𝑜𝑙𝑢𝑚𝑒 )
 is used to determine the BOD5. The sample 
volume is the amount of synthetic graywater placed in the bottles. The standard volume of the 
bottle is 300mL. 
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
A period of five days, they will be taken out and DO will be read again. This will define 
the efficiency of each column in the removal of organic matter influential. The BOD5 
spreadsheet will also cataloged in order to compare with the previous BOD`s. 
 
Results and Analysis 
ISFs have the potential to make the reuse of gray water for irrigation applications viable 
and very economic, since it has a low cost treatment, ease operation and maintenance, and it is 
very efficient. 
 
According to the EPA recommended BOD values for utilization of water in irrigation 
processes are 25 mg/L. Figure 3 and 4 present influent and effluent BOD5s values for the group 
1 and 2 columns. These results indicate that ISFs can effectively treat synthetic gray water to the 
EPA recommendation. 
 
Figure 3. BOD5 removal from 3-4-6 columns 
 
0
50
100
150
200
250
300
350
400
450
0 20 40 60 80 100 120 140 160 180
B
O
D
 (
m
g/
L)
Day
BOD5, mg/l (Avg.) INFLUENT BOD5, mg/l (Avg.) ALIX
BOD5, mg/l (Avg.) CHARLIE BOD5, mg/l (Avg.) JOE
Vacation Stress 
Efficiency Test 1 
Efficiency Test 2 
25 mg/L 
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
 
Figure 4. BOD5 removal from 4-4-4 columns 
 
The removal efficiency for both groups of columns was calculated using Equation 1 and is 
presented in Figure 5 and 6: 
 
𝐵𝑂𝐷 𝑅𝑒𝑚𝑜𝑣𝑎𝑙 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦% =
𝐼𝑛𝑓𝑙𝑢𝑒𝑛𝑡 𝐵𝑂𝐷5 − 𝐸𝑓𝑓𝑙𝑢𝑒𝑛𝑡 𝐵𝑂𝐷5
𝐼𝑛𝑓𝑙𝑢𝑒𝑛𝑡 𝐵𝑂𝐷5
∗ 100 
Equation 2. BOD Removal Efficiency 
 
Analyzing these figures is possible to conclude that after day 91, the sand filter achieved 
the steady state all columns have shown similar and high efficiency in the gray water treatment. 
 
0
50
100
150
200
250
300
350
400
450
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280
B
O
D
 (
m
g/
L)
Day
BOD5, mg/l (avg) INFLUENT BOD5, mg/l (avg) LUCIUS
BOD5, mg/l (avg) EVAN BOD5, mg/l (avg) BEN
25 mg/L 
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
 
Figure 5. BOD5 Removal Efficiency 3-4-6 Columns 
 
 
Figure 6. – BOD5 Removal Efficiency 4-4-4 Columns 
 
The COD analysis also reported the good treatment of the sand filters, even with the 
increased on COD from 300 to 600 mg/l the columns continued to have high treatment, showing 
0
20
40
60
80
100
0 20 40 60 80 100 120 140 160 180 200
P
er
ce
n
t 
(%
)
Day
BOD5 Removal Efficiency ALIX BOD5 Removal Efficiency CHARLIE BOD5 Removal Efficiency JOE
0
20
40
60
80
100
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280
P
e
rc
e
n
t 
(%
)
Day
BOD5 REMOVAL EFFICIENCY LUCIUS BOD5 REMOVAL EFFICIENCY EVAN
BOD5 REMOVAL EFFICIENCY BEN
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
COD values around 12 mg/l. The figure c and d below show the COD analysis on both group of 
columns. 
 
 
Figure 7. COD Analysis 3-4-6 Columns 
 
 
Figure 8. COD Analysis 4-4-4 Columns 
 
The constant volume data showed in Figure e and f means that the work in the lab was 
made without lack of sample or mistakes, ensuring the accuracy of the results. 
0
100
200
300
400
500
600
700
0 20 40 60 80 100 120 140 160 180 200
CO
D
 (
m
g/
L)
Day
COD (Avg.) INFLUENT COD (Avg.) ALIX COD (Avg.) CHARLIE COD (Avg.) JOE
0
100
200
300
400
500
600
700
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280
m
g/
L
Day
COD (Avg.) INFLUENT COD (Avg.) LUCIUS COD (Avg.) EVAN COD (Avg.) BEN
Vacation Stress 
Efficiency Test 1 
Efficiency Test 2 
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
 
Figure 9. Effluent Volumes 3-4-6 Columns 
 
 
Figure 10. Effluent Volume 4-4-4 columnsAlso with all data is possible to make a relationship between the four columns with 4” 
diameter to compare their efficiency during the experiment period. Figure g shows the BOD5 
0
100
200
300
400
500
600
700
800
0 20 40 60 80 100 120 140 160 180 200
m
L
Day
Effluent Volumes ALIX Effluent Volumes CHARLIE Effluent Volumes JOE
50
100
150
200
250
300
350
400
450
73 93 113 133 153 173 193 213 233 253 273
m
L
Day
EFFLUENT VOLUME, mL LUCIUS EFFLUENT VOLUME, mL EVAN EFFLUENT VOLUME, mL BEN
V
a
c
a
ti
o
n
 T
e
st
 
E
ff
ic
ie
n
c
y
 T
e
st
 1
 
E
ff
ic
ie
n
c
y
 T
e
st
 2
 
V
a
c
a
ti
o
n
 T
e
st
 
E
ff
ic
ie
n
c
y
 T
e
st
 1
 
E
ff
ic
ie
n
c
y
 T
e
st
 2
 
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
removal efficiency in the 4” columns. Even with a different period of time, the column with 
1gpd/ft2 achieved the steady state and it has shown the same efficiency than the columns loaded 
with 0.6 gdp/ft2, 0.9 gdp/ft2, and 1.2 gdp/ft2. 
 
Figure 11. BOD5 Removal Efficiency of 4” diameter columns 
 
Discussion and Conclusion 
Graywater reuse is a potential alternative option to be used as irrigation and the study 
revealed that the Intermittent Sand Filter is efficient to filtrate the household waste water, the 
values obtained for all the six columns were satisfactory. The BOD5 Efficiency results were 
close to 100% for all the columns in the research. However, to the filters achieve the maximum 
efficiency in the removal of organic matter is necessary some days of running, as shown by the 
Figure 5 and Figure 6. The column with higher diameter obtained best results in a smaller time 
step. 
The EPA standard for BOD5 is 25 mg of organic matter per liter, and with the study the 
columns presents values 25 times smaller than the EPA standard. Therefore, is possible to 
0
10
20
30
40
50
60
70
80
90
100
0 20 40 60 80 100 120 140 160 180 200
P
er
ce
n
ta
ge
 (
%
)
Day
CHARLIE LUCIUS EVAN BEN
2015 Proceedings of the Environmental Engineering Program at Mercer University 
 
Mercer University, School of Engineering, 1501 Mercer University Dr, Macon, GA 31207 - 2015 
increase the field rate and make the project more efficient in the economic way and in aspects of 
the amount of graywater filtrated and the removal of organic matter. 
 
Reference 
Odeh R. Al-Jayyousi, 2003. Greywater reuse: towards sustainable water management. 
 
Fangyue Li, Knut Wichmann, Ralf Otterpohl, 2009. Review of the technological approaches for 
grey water treatment and reuses. 
 
Agunwamba, J.C., Ukpong, E. C., 2012. Grey Water Reuse for Irrigation. 
 
Wastewater Technology Fact Sheet Intermittent Sand Filters EPA, 1999. 
 
B. Jefferson, A. Palmer, P. Jeffrey, R. Stuetz and S. Judd, 2004. Grey Water Characterization 
and Its Impact on the Selection and Operation of Technologies for Urban Reuse. 
 
Cornelia Merz , René Scheumann , Bouchaib El Hamouri , Matthias Kraume, 2006. Membrane 
bioreactor technology for the treatment of greywater from a sports and leisure club. 
Eva Eriksson, Karina Auffarth, Mogens Henze, Anna Ledin, 2001. Characteristics of grey 
wastewater. 
Abdallaa, K.Z. and Hammamb, G., 2014. Correlation between Biochemical Oxygen Demand and 
Chemical Oxygen Demand for Various Wastewater Treatment Plants in Egypt to Obtain the 
Biodegradability Indices. International Journal of Sciences: Basic and Applied Research 13 (1), 
42. 
 
Eriksson, E., Auffarth, K., Henze, M., & Ledin, A. (2001, October 25). Characteristics of grey 
wastewater. Elsevier, 85-104. 
 
Haering, K. C., Evanylo, G. K., Benham, B., Goatley, M. (2009). Water Reuse: Using Reclaimed 
Water for Irrigation. Virginia Polytechnic Institute and State University. Publication 452-014. 
 
Halling-Sørensen and Jørgensen, (1993). B. Halling-Sørensen, S.E. Jørgensen. Removal of 
Nitrogen Compounds from Waste Water. Elsevier, Amsterdam (1993), p. 39-40. 
 
Rafat Khalaphallah. (2012, September 27). Greywater treatment for reuse by slow sand ltration : 
study of pathogenic microorganisms and phage survival. Other. Ecole des Mines de Nantes. 
 
U.S. Environmental Protection Agency, (1999, September) .Wastewater Technology Fact Sheet 
Intermittent Sand Filters.