Treatment of Grey Water for Toilet Flushing Use

This study is the preliminary study ontreating grey water for toilet flushing use. Due to
the increment number of students in Universiti Teknologi PETRONAS (UTP), the
accommodations are also increased. This will result the increasing need of water use, in
future. Thus, the recycling of grey water is recommended to overcome the problem. The
recycled grey water will be use for toilet flushing system in UTP student's village. The
main objective of the study is to find ways to treat grey water as of to reduce highquality
fresh water supply for toilet flushing purpose and to propose a grey water
recycling system. Besides that, an economic study on using grey water for toilet flushing
use was done. This project consists of two parts, which are to analyze the wastewater
before and after treatment and to find the best treatment method using the available
equipment in UTP by conducting a laboratory work. Based on the findings from the
experiment, treatment methods are proposed to treat the grey water for toilet flushing
use in UTP. Then, a brief economics analysis is required to check on cost and water
saving if the treatment system is implemented in UTP. The methodology used for
treatment of grey water including the experimental work that available in the UTP
laboratory which is Coagulation and Flocculation, Sequencing Batch Reactor (SBR) and
Chlorination. Other methods used are to analyze the parameters before and after the
treatment. Results obtained from the experiment shown that the coagulation and
flocculation treatment is the suitable method to treat turbidity of the grey water. The 70
mg/L alum dosages at pH 6.5 are the optimum value determined in order to reduce the
turbidity. SBR treatment has shown a reduction in BOD for 1-hour time and chlorination
method is able to reduce theMPN of total coliform with optimum chlorine dosage at 28
mg/L. Thecost study analysis shows that the water consumption and water bill saving is
by 87 % and 84%, respectively.