Preliminary analysis of phosphorus flow in Hue Citadel

Abstract

Characteristics of waste and wastewater management can affect material flows. Our research investigates the management of waste and wastewater in urban areas of developing countries and its effects on phosphorus flow based on a case study in Hue Citadel, Hue, Vietnam. One hundred households were interviewed to gain insight into domestic waste and wastewater management together with secondary data collection. Next, a phosphorus flow model was developed to quantify the phosphorus input and output in the area. The results showed that almost all wastewater generated in Hue Citadel was eventually discharged into water bodies and to the ground/groundwater. This led to most of the phosphorus output flowing into water bodies (41.2 kg P/(ha year)) and ground/groundwater (25.3 kg P/(ha year)). Sewage from the sewer system was the largest source of phosphorus loading into water bodies, while effluent from on-site sanitation systems was responsible for a major portion of phosphorus into the ground/groundwater. This elevated phosphorus loading is a serious issue in considering surface water and groundwater protection.

An Alternative Method to Estimate Influent Concentration Using On-site Lab-scale Activated Sludge Reactors

“…As the septic tank is a sort of decentralised module to reduce the pollutant load, a part of readily biodegradable materials in the wastewater is decomposed in a certain extent during the storage in the tank [2]. However, in reality the performance of the septic tank process is recognised to be considerably scattered over the areas and the households due to no concrete design guideline and lack of regular maintenance [3,4]. According to World Bank [1], the effluent of the septic tank to the sewer in Vietnam noticeably varied, e.g.…”

Environmental Sustainability Opportunities at Informal Settlements in Unesco World Heritage Areas: A Case Study of Hue, Vietnam

“…In addition to faecal coliforms; E. coli (Escherichia coli) and COD (chemical oxygen demand) measurements were also found to exceed regulations [14]. Phosphorus levels were found to be very high in the Citadel (41.2 kg P/ha year) with untreated sewage the largest source of phosphorus loading [26]. Extremely high nitrogen levels have also been recorded.…”

Dynamic Estimation of Hourly Fluctuation of Influent Biodegradable Carbonaceous and Nitrogenous Materials Using Activated Sludge System

“…where: From the equation (5), the part of K L a(C* − C L ) represented the oxygen transfer rate (OTR) from the gas to liquid phase, in which C L was determined as the constant value whilst Xq O2 was the oxygen uptake rate of microorganism (OUR). When dC L ⁄dt became almost zero, K L a could be obtained from (C* − C L ) and Xq O2 in numerical manner [14,15].…”

“…Since septic tank is a kind of decentralized component contributing to reduction of pollutant load, a portion of biodegradable materials is decomposed during the period of retention [3]. Nevertheless, due to accumulation of pollutant associated with lack of regular maintenance, it is recognized that the septic tank process cannot produce high performance which remark-ably differs over areas and household [4,5]. Accordingly, the constituents and concentration of effluent from septic tank to combined sewage system which was the typical class in urban areas considerably varied, e.g.…”

“…Accordingly, the constituents and concentration of effluent from septic tank to combined sewage system which was the typical class in urban areas considerably varied, e.g. BOD 5 : 36 − 135 mg/L, SS: 27 − 196 mg/L and Total Nitrogen: 11 − 40 mg-N/L [1]. In addition, because the combined sewerage systems in Vietnam play a role in collecting both wastewater and storm water which probably carries surface pollutant, the variation in influent concentration possibly becomes more enormous.…”