No abstract

This study investigated the characteristic of aerobic granular sludge (AGS) process to treat the sewage having low carbon/nitrogen ratio (Biochemical oxygen demand (BOD5):Total nitrogen (T-N), 4.5:1) in sequencing batch reactor (SBR). The removal efficiency of BOD5, suspended solid (SS), T-N and phosphorus (PO4 3-P) were 92.6%, 64.3% and 90.1%. Concentration and size of AGS were changed in proportion to the organic matters and nitrogen concentration of the influent (Concentration and size of AGS: 1,700-3,000 mg/L, 0.5-1.0 mm). Mixed liquor suspended solid (MLSS) also changed with the concentration of AGS (MLSS: 2,000-3,500 mg/L). When the settling time was shortened from 15 min to 10 min, size and shape of AGS were maintained (Size of AGS: 1.0-1.5 mm). In addition, the concentration of AGS and MLSS increased (Concentration of AGS: 3,500 mg/L, MLSS: 4,000 mg/L). Concentration, size and shape of AGS were affected the settling time of the reactor more than the concentration of organic matter and nitrogen in the influent. In the results of removal efficiency and changes in AGS, we confirmed that the SBR process using AGS can be used to treat the sewage having low carbon/nitrogen ratio by applying short settling time.

No abstract

Hanoi is the capital of the Socialist Republic of Viet Nam. It is also the political, economic and cultural center of the Red River Delta area and Viet Nam. Hanoi City is the first large urban center in Vietnam to adopt the Green Corridor model as part of the master plan approved in 2011, which is somewhat similar to the green belt model widely adopted in urban areas in the world. The green corridor for Hanoi includes “rural areas, systems of rivers, lakes, hills, natural forests, farming areas … strictly protected to provide logistics support for urban development, landscape protection and healthy urban environment”. The green corridor for Hanoi includes the entire suburban areas, which play a role in controlling the sprawling development of the central urban hub and occupy nearly 70% of the city’s land area. This solution also causes a lot of controversy on how the concept should be interpreted as the structural planning does not reflect natural conditions and there remain difficulties in the management of such a plan in practice. Using field surveys, graphic presentation and literature review, the article identified existing problems in development of a Green Corridor plan for Hanoi. Based on these problems, the article presented the concept, planning structural model and some solutions for management of the urban green corridor for Hanoi.

No abstract