Water Quality; Wastewater Management Essay Example | Topics and Well Written Essays - 500 words

Water Quality; Wastewater Management - Essay Example The wastewater having very high amount of dissolved BOD or COD would require either biological treatment processes, like activated sludge treatment, trickling filters upflow anaerobic sludge treatment, or chemical treatment units like coagulation techniques, filtration with ion exchange etc. These methods would not be adequate for complete elimination of the dissolved impurities. For example in the case of municipal wastewater, the secondary treatment would results in the reduction of organic part of the total contaminants dissolved in it. On the other hand, the pollutants like nitrates and phosphates or bacterial/microbiological contamination would not be totally removed using these methods. Hence, advanced treatment operations are additionally required for the removal of the aforementioned impurities (Malzer, 2002). The treatment processes employed in such situations are classified as the tertiary treatment. The techniques are usually nitrification and denitrification units which a re also biological methods undertaken with the help of bacterial mass. On the other hand, phosphates too need specialized treatment units for its removal. Further, if the objective is to eliminate the bacterial contamination, disinfection systems need to be provided appropriately as the tertiary unit operation. Thus the methods used under the secondary and tertiary treatment units are of multiple types and each having different purpose. Thus in a typical treatment system where the secondary operations are dependent on the activated sludge plants, the operations consist of a series of inter linked units having a settling basin where the sludge is separated from the treated water, following by sludge thickening, sludge drying and sludge disposal. The treated water from the settling tank marks the end of secondary treatment operations the water would still

Gary Nash Essay Example | Topics and Well Written Essays - 2500 words

Gary Nash - Essay Example Jensen. While the former never wrote or lectured on issues of race in early America, Gary Nash seeks to emulate the progressive nature of Merrill Jensen’s research and writing. The scope of Race and Revolution is the years just prior to the American Revolution through the decades following the signing and ratification of the U.S. Constitution. In the broadest sense, the book chronicles the evolving social, political and economic realities of the African-American experience during these years. Individual experiences are shared in an effort to show the differences between three distinct periods of time within the scope of the book. During the pre-Revolutionary War years, the rights and privileges of freed blacks are examined. Their equality in society and economic matters is highlighted. The pre-war years also seemed to hold a universal agreement by whites that it wasn’t a matter of if slavery would be abolished but when. Many held that slavery was incompatible with the ideals held by the founders of the republic. During the war, many African-Americans joined the British in their fight against the colonists. The British offered immediate emancipation to any slave that would join their ranks. Many slaves left their families and masters behind. These years of recovery saw a lessening of support for the abolition of slavery. Nash details the political and personal decisions that weakened the cause of the abolitionists and moved popular opinion towards a less optimistic view of black Americans, both free and enslaved. By the ratification of the U.S. Constitution, it was clear that African-Americans of all social classes and degrees of emancipation would not be granted full part in the new republic. They were to be insulted, degraded and relegated to second-class citizenship if free and continued servitude if enslaved. The final portion of the book examines the social evolution of institutions such as the establishment of