Evaluation of the water quality and toxicity of wastewater in the
carwash industry in City of Tshwane: An analyses of the
preliminary results
By
Ms. Sbongile Phungula
Professor M. Tekere
Mr. K Maphangwa
Tshwane Research Symposium
23 April 2015
Introduction
Car washing consumes large quantities of water
and discharge large amounts of wastewater.
Car washes have received scant attention as a
potential source of pollution globally.
Effluent from car washes has the potential to
contaminate and pollute water resources thereby
causing a threat to the environment.
Many chemical pollutants, dirt and traffic film residue are washed off from cars – can be detrimental to ecosystem if discharged untreated.
Zinc – from tires and brakes, lead – break lining and tyres, engine washing and lead paints, car batteries,
COD, phosphates – detergents, copper –brake dust, Calcium – tyre source,
chromium – yellow road lining marks during heavy traffic, washing of chromium coated parts such as bumpers and wheels.
Gasoline, diesel, motor oil – engine leaks and fuel combustion processes,
surfactants – detergents and cleaning agents.
Objectives
To evaluate the level of car wash activities
and water use in the carwash industry.
To collect and analyse wastewater from the
carwash industries in selected areas in City
of Tshwane
To carry out toxicological studies on the
waste water
To determine the microbial characteristics
of carwash wastewaters
Study area
Sampling sites & ProcedureCar washes in the City of Tshwane were
approached and 6 agreed to participate –different categories Commercial car washesin garages & High density/ illegal car washes.
Denoted CW1 – CW6
7 different bottles collected in each facility once every 3 months
Analyzed at Waterlab (Pty) & Water and Sanitation (Pretoria)
Car wash wastewater Chemistry resultsDeterminants CW1 CW2 CW3 CW4 CW5 CW6
Ammonia (NH4) 1.163 0.605 3.961 2.17 <0.100 12.686
Chloride 55.3 23.3 17.2 36.5 35.2 30.5
Conductivity 67.8 29.7 40.4 37.3 39.4 56.8
Hardness (CaCO3) 257.5 89.8 99.5 69.6 90.7 171.5
pH 7.7 7.7 7.3 7.9 7.8 7.6
Total Phosphate as P 0.553 0.426 1.450 1.009 4.208 0.765
Sulphate as SO4 40.1 13.2 64.7 23.3 8.9 26.6
Kjeldalh Nitrogen 3.75 4.374 7.537 7.194 3.718 13.955
Phosphates as P 0.147 0.026 0.153 0.254 4.179 0.502
Turbidity 23.9 10.4 107 113 108 28.9
Calcium 55.3 25.7 27.7 18.2 20.8 39.4
Red: Exceeding Tshwane limits for pollution in sewage
Blue: Exceeding National environmental standard for discharge of effluent into water or land, 1999
Orange: Exceeding WHO effluent standards
wastewater Chemistry results cont…Determinants CW1 CW2 CW3 CW4 CW5 CW6
Anionic Surfactants 25.6 7.5 41.1 32.8 47.5 38.6
TPH - DRO <1.0 2.3 26 6.7 17 <1.0
TPH-GRO <0.010 <0.010 <0.010 <0.010 <0.010 <0.010
Oil & grease 3 7 24 3 8 18
COD 113 200 416 280 240 160
BOD 20 27 120 81 48 54
TDS 408 232 320 286 842 326
TSS 36 48 181 101 59 54
Chromium <0.003 <0.003 <0.003 <0.003 <0.003 <0.003
Copper <0.005 0.008 0.070 0.035 <0.005 <0.005
Iron 0.038 0.972 1.243 2.285 0.044 0.530
Nickel <0.004 <0.004 0.005 <0.004 <0.004 <0.004
Lead <0.008 <0.008 <0.008 <0.008 <0.008 <0.008
Zinc <0.005 <0.005 0.993 0.788 <0.005 <0.005
Red: Exceeding Tshwane limits for pollution in sewage
Orange: Exceeding WHO effluent standards
Blue: Exceeding National environmental standard for discharge of effluent into water or land, 1999
Car wash wastewater Toxicity results
Car wash wastewater Toxicity results
Determinant CW1 CW2 CW3 CW4 CW5 CW6
Toxicity unit
(TUa)
<1 <1 2.5 8.3 <1 <1
Toxicity test results 30 minutes Vibrio Fischeri bioluminescent test toxicity unit
Toxicity unit Conclusion
<1 Limited to not Acutely Toxic
1-2 Negligibly Acute Toxic
2-10 Mildly Acutely Toxic
10-100 Acutely Toxic
>100 Highly Acutely Toxic
Toxicity units (TUa) (Tonkes and Baltus, 1997)
Car wash wastewater Bacterial results
Car wash activities: Exterior wash & go, Full
valet (exterior, interior, engine, chassis).
One facility recycle & reuse water
Other facilities discharge into sewer system &
drainage
Have no permits for discharging water
Not aware of regulations & discharge limits
No knowledge of quality of wastewater they
discharge.
Use average 600kl water per month
Car wash questionnaire results
The study is ongoing – more samples to be taken to improve quality of results.
Preliminary results suggest wastewater from car washes has some pollutants that has potential to pollute water resources which cannot be neglected.
Most facilities are not aware of the laws and regulations governing Car wash wastewater management.
Although these results might not show much pollution but significant amount of contaminants are generated annually from car washing including residential car washing.
Conclusions
Professor M. Tekere – UNISA
Mr. K. Maphangwa – UNISA
Dr. Mike Silberbauer – Water & Sanitation
Water & Sanitation - Biology lab, Trace lab
& Inorganic lab personnel
Water lab (Pty) for analysis
Water & Sanitation – Resource quality
monitoring colleagues
Acknowledgements
Damha C, Utete B, Soropa G and Rufasha S.B 2014: Potential impact of Wash Bay Effluent on the water quality of Subtropical River. Journal of water resource and protection. 6, 1045-1050.
Lau WJ, Ismail AF, and Firdaus S 2012: Car wash industry in Malaysia: Treatment of car wash effluent using ultrafiltration and nanofiltration membranes. Separation and purification technology. 104, 26-31.
Yasin S, Iqbal T, Arshard Z, Rustan M & Zafar M 2012: Environmental pollution from automobile vehicle service stations. Journal of quality and technology management. 8, 61-70.
References