Đánh giá khả năng cung cấp oxy hòa tan vào trong nước thải bằng ống venturi
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Abstract
This study was conducted to assess the potential of the venturi tube for dissolved oxygen supply into the wastewater. The experiments were carried out by two independent aeration types, including a venturi two nozzle-tube and air compressor-porous air stone systems. DO concentration was measured over time in the water tank and theoretical oxygen transfer rate was calculated. After 240 minutes of operation, the venturi tube-ejector model resulted in a DO concentration from nearly 0 mg/L up to over 8.1 mg/L at the central of the tank and 7.3 mg/L at the surrounding measured points, which is higher than that of the air compressor-porous air stone. In addition, the oxygen transmission coefficient Kla20max reaches 4.23 and (SOTR-the standard oxygen transfer rate)max was 1.1x10-2 kgO2/h of using the venturi device to suck the air and supply it to water through a nozzle. This study shows that the venturi two nozzle-tube system was better in supplying dissolved oxygen compared to the air compressor-porous air stone system in wastewater.
Tóm tắt
Nghiên cứu này được thực hiện nhằm mục tiêu đánh giá khả năng cung cấp oxy hòa tan của ống venturi vào trong môi trường nước thải. Thí nghiệm được thực hiện để đánh giá hai kiểu sục khí hoạt động độc lập gồm ống venturi kết hợp hai vòi phun và máy thổi khí nén qua đá sủi bọt. Nồng độ oxy hòa tan trong nước được đánh giá liên tục theo thời gian và tỷ lệ truyền khối oxy vào trong nước được tính toán. Sau 240 phút vận hành hệ thống, kết quả thí nghiệm cho thấy mô hình ống venturi-vòi phun cho giá trị DO từ xấp xỉ 0 mg/L trước khi sục khí lên đến đạt 8,1 mg/L tại vị trí trung tâm bể và 7,3 mg/L ở vị trí đo xung quanh sau thời gian sục khí, cao hơn so với hệ thống khí nén-đá bọt khoảng 1,0 mg/L. Bên cạnh đó, hệ số truyền oxy Kla20max đạt 4,23 và tốc độ truyền oxy tiêu chuẩn SOTR là 1.1x10-2 kgO2/h. Kết quả nghiên cứu cho thấy hệ thống ống venturi-vòi phun hoạt động tốt hơn trong việc cung cấp oxy hòa tan so với hệ thống cấp khí nén qua đá sủi trong môi trường nước bị ô nhiễm.
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