Environmental Assessment of Household greywater in Chattogram City, Bangladesh

Abstract

Untreated greywater which negatively impacts our environment are directly discharged. This greywater have a huge potential in terms of treatment and reuse unlike the traditional wastewater which needs large-scale centralized treatment plants to be built with huge infrastructural costs. Therefore this paper studies the primary quality of greywater present in Chattogram city by conducting an environmental assessment of the greywater. 10 greywater samples were collected for chemical analysis and 5 for microbial examination from 5 different locations in Chattogram City. Water parameters like pH, Total Dissolved solids (TDS), Electric conductivity (EC), Total hardness, Dissolved Oxygen (DO), Oxidation– Reduction potential and other chemical analysis such as fluoride, chloride, phosphates, Sulphate, and nitrate levels were tested. Also, MPN tests were done on the greywater samples to find the total coliforms and fecal coliforms CFU/100 ml after which the coliforms were cultured on EMB to see the patterns of the colonies present. Parameters like Electrical Conductivity, pH, Dissolved Oxygen, Total hardness, Fluoride, Nitrates and sulphates were found to be suitable for wastewater reuse in irrigation without almost any improvement as they maintained international standards. On the other hand, the turbidity for the samples ranged from 21.0 NTU to 239 NTU which was higher than the standard turbidity level of 2 NTU which affects soil texture, reduces hydraulic conductivity of the soil and contaminates soil surface. Also, fecal coliforms were present in all samples and were less than 10000 CFU/100 ml which is why this greywater could be used for unrestricted irrigation without treatment. However, it was deducted that the water needed to be treated for biological impurities because the total coliform counts were more than 1100 CFU/ 100 ml for all the samples which could result in diseases and infections. Moreover, the Chloride level in the water was found to be high ranging from 5.07 mg/L to 100.7 mg/L which needs to be treated because high levels of Chloride in Irrigation could cause leaf burns and damages in plant tissues. The paper further reviews low-cost treatment systems from Kenya, India and Egypt which could be used in a developing country like Bangladesh for the treatment for use in irrigation purposes. Moreover, this paper gives recommendations on how the situation of greywater can be improved by looking into proper management aspects.