title: Analysis of nitrogenous and algal oxygen demand in effluent from a system of aerated lagoons followed by polishing pond.
abstract: In this descriptive-analytical study, nitrogenous and algal oxygen demand were assessed for effluent from a system of facultative partially mixed lagoons followed by the polishing pond using 120 grab samples over 1 year. Filtered and non-filtered samples of polishing pond effluent were tested in the presence and absence of a nitrification inhibitor. Effective factors, including 5-day biochemical and chemical oxygen demand (BOD and COD), total suspended solids (TSS), dissolved oxygen, chlorophyll A, and temperature, were measured using standard methods for water and wastewater tests. The results were analyzed using repeated measures analysis of variance with SPSS version 16. Findings show that the annual mean of the total 5-day BOD in the effluent from the polishing pond consisted of 44.92% as the algal carbonaceous biochemical oxygen demand (CBOD), 43.61% as the nitrogenous biochemical oxygen demand (NBOD), and 11.47% as the soluble CBOD. According to this study, the annual mean ratios of algal COD and 5-day algal CBOD to TSS were 0.8 and 0.37, respectively. As the results demonstrate, undertaking quality evaluation of the final effluent from the lagoons without considering nitrogenous and algal oxygen demand would undermine effluent quality assessment and interpretation of the performance of the wastewater treatment plant.
authors.affiliation: Assist. Prof. of Social Determinants of Health Research Center and Environmental Health Department, School of Public Health, Urmia University of Medical Sciences, Urmia, Iran E-mail: hassankhorsandi@yahoo.com.
authors.forename: Hassan
authors.initials: H
authors.lastname: Khorsandi
authors.affiliation: Municipal Water and Wastewater Company of West Azerbaijan province, Urmia, Iran.
authors.forename: Rahimeh
authors.initials: R
authors.lastname: Alizadeh
authors.affiliation: Municipal Water and Wastewater Company of West Azerbaijan province, Urmia, Iran.
authors.forename: Horiyeh
authors.initials: H
authors.lastname: Tosinejad
authors.affiliation: Municipal Water and Wastewater Company of West Azerbaijan province, Urmia, Iran.
authors.forename: Hadi
authors.initials: H
authors.lastname: Porghaffar
mesh_terms: D001673:Biodegradation, Environmental; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D002734:Chlorophyll / Q000737:chemistry; D000077194:Chlorophyll A; D000460:Chlorophyta / Q000737:chemistry*; D004784:Environmental Monitoring / Q000379:methods; D005374:Filtration; D009584:Nitrogen / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D061005:Ponds; D012722:Sewage; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D002734:Chlorophyll; D000077194:Chlorophyll A; D009584:Nitrogen; D010100:Oxygen; D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical