摘要：交替式生物處理池工藝(UNITANK)是藝處結合傳統活性污泥法和SBR法的優點形成的一種新型的活性污泥處理工藝，由三個矩形池串聯組成(A，理城B，市污水C池)，藝處池內設曝氣設備。理城交替式生物處理池按周期進行，市污水B池連續曝氣，藝處兩側池內間斷曝氣，理城交替作為沉淀池和曝氣池，市污水進水交替進入A、藝處B、理城C池，市污水出水相應地從C、藝處A池引出。理城系統中省去傳統工藝中的市污水初沉池和污泥回流設施

關鍵詞：交替式生物處理池 UNITANK城市 污水

　　石家莊高新技術產業開發區污水處理廠日處理污水10萬噸，采用UNITANKTMIM工藝，占地7.2公頃。這是此工藝在國內(除澳門外)的首次應用。該污水處理廠進水水質指標為：BOD5≤400mg/L，SS≤400mg/L，COD≤600mg/L；出水水質要求：DOD5≤30mg／L，SS≤30mg／L，COD≤120mg/L。

　　處理工藝過程為：原污水進入格柵間，在此攔截污水中飄浮物，由污水泵提升，經細格柵進一步去除水中雜質，進入沉砂池去除砂粒，然后進入UNITANK池，去除BOD5等污染物，混合液經沉淀分離，澄清液進入接觸池加氯消毒(季節性)后排入汪洋溝。剩余污泥經污泥泵送至集泥池，由帶預濃縮功能的脫水機處理后，泥餅外運。

　　該污水處理廠UNITANK 池共為六個組，每個組由三個正方形反應池組成，單池凈尺寸為長×寬×高＝35×35×7m，有效水深6米。兩側池采用周邊堰出水。每組平均設計流量為 0.193m3／s，污泥濃度4000mg／l，泥齡為14天，污泥負荷0.113kgBOD／KgMLss／d，沉淀池最大表面負荷0.74m3／m2h。

　　該系統實際需氧量為60噸O2天。曝氣系統采用表曝機和潛水攪拌機結合的方式，表曝機運行充氧，水下攪拌機用于輔助攪拌。表曝機選用浮動式高速表曝機，可適應水面起落，安裝簡單，維護方便。

　　UNITANK工藝據有獨特的優點：第一，結構緊湊，節省工程用地和土建費用；第二，設備種類較少，便于維護管理；第三，采用時序控制，形成厭氧、缺氧和好氧狀態，實現除磷脫氮功能，運轉靈活；第四，容積和設備利用率高。

　　UNITANK工藝雖有許多優點，但也有一定的適用范圍。在選擇該工藝時應該考慮以下問題：

　　第一，進水BOD濃度較高時，建議考慮采用兩級UNITANK工藝。第一級生物池按高負荷厭氧或好氧方式運行，第二級按低負荷好氧方式運行。

　　第二，出水水質有除磷要求時，應慎重考慮，因為該工藝很難形成生物除磷的理想厭氧狀態。

　　第三，處理水量過大時，該工藝的復雜程度將大大提高。

　　綜上所述，UNITANK工藝更適用于中小型污水處理廠，在一定的范圍內，可以替代其它活性污泥法，有獨特的優點，并具有較強的競爭力。

　　Abstract：The altemative biological treatment (UNITANK®) is a new combination of advantages of traditional activated sludge process and SBR. It consists of one rectangular reactor which is divided in three compartments (basin A,B,C). Each compartment is equipped with an aeration system. The process works according to a cyclic operation. In compartment B aerated continuously, in compartment A and C ether aerated or settled, the waste water is fed to compartment A, B and C alternatively, the cleaned water is discharged form compartment C and A. There are not primary settling tanks and sludgereturn facilities that are installed in traditional process.

　　The wastewater treatment plant of the ShijlaZhuang Economic Zone is the first plant using UNITANK® in China except Marco. It can treat 100,000 cubic meters municipal wastewater every day and is 7.2 ha area.

　　The influent characteristics of the plant are as follows: BOD₅≤400mg/L,SS≤400mg/L,COD≤600mg/l; The effluent discharge values will be: BOD₅≤30mg/l, SS≤30mg/l, COD≤120mg/l.

　　The general description for the process is as follows: the raw wastewater is collected in the inlet pump station, big suspending materials will be retained by means of coarse. After inlet pump lift, the raw water flow through fine screens, small suspending materials removed. In the grit chamber, the sand is reactions of micro-organisms, the substances such as BOD, are degraded. After the grit chamber, the sand is removed from the raw water. Then, the water flow in the UNITANK® . Using the metabolic reactions of micro-organisms, the substances such as BOD, are degraded. After biological treatment, the sludge settles by gravity, the clean water is disinfected seasonally and finally discharged to Wangyang River. The excess sludge is pvmped to the sludge storage tank in which the sludge is stored temporarily, and then is thicken by means of mechanical sludge dewatering.

　　There are six lanes for this project. each of them consists of three compartments which size is 35 meters long, 35 meters wide and 7 meters high, and 6 meters water deep. In compartment A and C, there are overflow weirs around basins. Each lane has a average capacity of 0.193m³of waste water per day. The average sludge concentration is 4000mg/l. The average sludge loading is 0.113kgBOD/kgMLSS/d. The sludge age is 14 days. Maximum surface loading is 0.74m³/²h when the compartment A and C are used as settling tank.

For this project, the actual oxygen demand is 60000kg/d. The aeration system consists of surface aerators and submersible mixers. The aerators areate aerobic conditions, the mixers keep sludge suspending and enhance oxygen uptake. Because the aerators are floating type,so they can adapt to the water surface up and down. and easy to install and maintenance.

　　UNITANK® have their particluar advantages: First, it is construction-compact, spacesaving and costeffective. Second, it is small kinds of equipment and easy to maintenance. Third, control in time can performs the anaerobic, anoxic and aerobic conditions in a same compartment, and realizes or enhances biological nutrient removal. Fourth, it has high usage ratio for equipment and construction volume.

Though the process has many advantages, it also has its own usage scope. When selecting the process, we suggest to consider the following items:

　　First, if the influent BOD value is very high, it is better to select two-stage UNITANK®system. The first stage is operating under high loading and anaerobic or aerobic conditions, the second stage is operating under low loading and aerobic conditions.

　　Second, if there is effluent phosphorus demand, it should be pay attention to select the process, because it is very difficult to produce the ideal anaerobic condition for biological phosphorus removal.

Third, if the treatment capacity is pretty high, the operation control system for the process will be very complex.

　　About all, UNITANK® has many particular advantages. It is suitable for wastewater treat ment plant on a small or medium scale. In certain scope, it can take place of many other activated sludge processes.

　　自1987年，比利時SEGHERS公司提出一種新穎的活性污泥去——UNITANK工藝，它集中了傳統活性污泥法和SBR的優點，處理單元一體化，經濟、運轉靈活，在歐洲及亞洲已有近2百座此種工藝的污水處理廠建成。

　　石家莊高新技術產業開發區污水處理廠(以下簡稱石家莊高新區污水處理廠)日處理污水10邁萬噸，經過工藝方案比較和論證，結合貸款國技術特點，決定采用UNITANK工藝。這是此工藝在國內 (除澳門外)的首次應用。

1.UNITANK工藝簡介

1.1 基本構造

　　UNITANK又稱交替式生物處理池，其基本單元是由三個矩形池組成(A，B，C池)，相鄰通過公共墻開洞或池底渠連通。三個池中都安裝有曝氣系統，可以是微孔曝氣頭、表曝機或潛水曝氣機：外側兩個池(A和C池)設有固定式出水堰及剩余污泥排放裝置，他們交替作為曝氣池和沉淀池，中間的池子 (B池)只能作為曝氣反應池。另外，污水通過閘門控制可以進入任意一個池子，采用連續進水，周期交替運行。如圖1所示。

1.2 運行方式

　　UNITANK運行按周期運行，一個周期包括兩個主階段和兩個中間階段，一般單個周期時間為7小時，主階段2×3小時，中間階段2×30分鐘。

1.2.1 主階段

　　第一主階段，污水首先進入A池，該池處于曝氣狀態，因上個階段進行沉淀操作，積累了大量活性污泥，且濃度較高。進水與活性污泥混合，有機物被吸附，部分被降解?；旌弦豪^續流入B池，該池通 常連續曝氣，有機物得到進一步的降解，同時在推流過程中，A池的活性污泥進入中間池，再進入C池，實現污泥在各池的重新分配。最后，混合液進入處于沉淀狀態的C池，進行泥水分離，處理后的出水通過溢流堰排放，剩余污泥由該池排出。為了防止A、B池的污泥被沖至C池，過量積累，每120—180分 鐘改變水流方向，即進入到下一個主階段。

　　第二主階段，污水先進入C池，污水及混合液的流動方向與第一階段相反。

1.2.2 中間階段

　　中間階段的作用是完成曝氣池到沉淀池的轉換。在第一主階段的中間階段，污水進入B池，C池仍處于沉淀出水狀態，同時A池開始進入沉淀狀態，為出水作準備。在第二主階段的中間階段，污水進入B池，A池仍處于沉淀出水狀態，同時C池開始進入沉淀狀態，為出水作準備。

　　因為邊池在曝氣狀態時，出水槽內進滿混合液，所以邊池進入沉淀狀態后，開始的出水不能作為處理后的出水直接排放，需用沖洗排人處理系統。待出水澄清后，方可外排。