Recycling of Alum from Water Treatment Residue and Reuse It as a Flocculating Agent for Raw Water Treatment

The chemical coagulation-flocculation technology is touted as one of the valuable techniques and widely used for wastewater treatment because of its simplicity and effectiveness. So far, a number of flocculants have been fabricated to ameliorate the flocculation process in water treatment such as alum, polyaluminium chloride. Despite its broad application in water treatment, accumulation of alum in sludge has been reported as the main source of a disposal problem. Furthermore, recent studies suggested that the presence of alum in sludge may lead to human health problems. Here in, we have used alkalization method to recover alum present in sludge collected from Kimisagara water treatment plant located in Kigali capital city of Rwanda. The recovered alum was used more than one time and showed excellent flocculation efficiency. Some physical parameters such as pH, Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Conductivity and Turbidity were systematically tested and compared with those of World Health Organization (WHO) and Rwanda Standards Board (RSB) standards for drinking water. The results showed that alum present in sludge can be recovered and reused for multiple times.

Hydroxyl,hydroperoxyl free radicals determination methods in atmosphere and troposphere

The hydroxyl radical(·OH)has a crucial function in the oxidation and removal of many atmospheric compounds that are harmful to health.Nevertheless,high reactivity,low atmospheric abundance,determination of hydroxyl,and hydroperoxyl radical’s quantity is very difficult.In the atmosphere and troposphere,hydroperoxyl radicals(HO_(2))are closely demanded in the chemical oxidation of the troposphere.But advances in technology have allowed researchers to improve the determination methods on the research of free radicals through some spectroscopic techniques.So far,several methods such as laser-induced fluorescence(LIF),high-performance liquid chromatography(HPLC),and chemical ionization mass spectroscopy have been identified and mostly used in determining the quantity of hydroxyl and hydroperoxyl radicals.In this systematic review,we have advised the use of scavenger as an advance for further researchers to circumvent some of these problems caused by free radicals.The primary goal of this review is to deepen our understanding of the functions of the most critical free radical(·OH,HO_(2))and also understand the currently used methods to quantify them in the atmosphere and troposphere.