余姚市小曹娥污水处理厂从污染到净化的转运奇迹

项目背景

浙江省余姚市小曹娥城市污水处理厂位于余姚市小曹娥镇，是余姚市最大的污水处理厂，服务范围包括主城区、姚北新城、小曹娥、黄家埠、临山、滨海园区、滨海新城、泗门、马渚、梁弄、高亭、新仓等，服务面积总计约120k㎡。本厂总用地面积19.16h㎡，远期规划规模30万m³/d，现状处理规模22.5万m³/d。工程经过一期、二期和三期一阶段的建设，一期工程分两批建设，每批为6万m³/d，其中一批工程于2004年建成运行，而二批工程则于2010年建成。

重难点分析

（1）进水水量难以调配及预处理设施不足

现状进水高位井缺乏配水措施，使得改造后各路配水均匀性受限。现有预处理构筑物中无格栅，因此后续处理构筑物中混有较大的悬浮物和漂浮物。此外，由于预处理设施的综合池具有一定的沉砂和水解酸化作用，但也消耗了进水中的碳源，对出 水TN提标不利。

（2）生物反应池容积偏小且二沉池负荷过高

现状生物反应池容积偏小，在当前进水低于设计值的情况下，只能勉强达到一级A标准，但无法满足更严格的清洁排放标准要求。一、二期二沉池表面 水力负荷较高（1.50m³/㎡·h），时有漂泥产生，这对稳定达标排放造成了挑战。

（3）榨菜废水严重影响正常运行

榨菜废water进入预处理站中的格栅井调节池，其出water入newly built榨菜废water mix sedimentation pool (3000 m³/d)。其out water经提升后进入pre-treatment station中的existing dissolved acidification pool，其out water与small Cao'e city wastewater treatment plant wastewater mixed into north side of small Cao'e factory, then enter two existing sedimentation pools.

（4）BOD5/CODCr比例偏低含有难降解有机质

本factory BOD5/CODCr在0.34左右，可生化性一般，因此需采取相关去除措施来减少对COD稳定达标的影响。

（5）管线布置复杂且紧张用地需求

3 设计方案

（1）工艺流程：

进入high-level inlet tank via new pumps.

Pre-treatment through fine mesh screens and aeration sedimentation tanks (20,500 m³/d + 9,500 m³/d).

Primary settling tank: upgraded to a side-flow clarifier.

Aeration basin: upgraded to Bardenpho process with five-stage nitrification-denitrification.

Secondary settling tanks: upgrade to include denitritation for enhanced nitrogen removal.

Sludge thickening and dewatering units: expansion of the sludge thickening unit and upgrading the dewatering unit.

The secondary effluent will be treated in an advanced oxidation stage using powdered activated carbon if required to meet stringent COD limits.

The final effluent will be disinfected with chlorine dioxide before discharge into the sea via a pumping station.

(2) 总平面布置：

New construction includes:

+ High-level inlet tank,

+ Fine mesh screens,

+ Aeration sedimentation tanks,

+ Side-flow clarifiers,

+ Bardenpho process aeration basins,

Upgrades include:

- Existing primary settling tanks converted into side-flow clarifiers,

- Existing biological reactors converted into Bardenpho process units,

Expansion includes:

- Sludge thickening and dewatering units.

All new structures are located within the existing site boundaries with minimal impact on operations during construction period.

(3) 施工期间运行保障：

To ensure normal operation during construction, three measures were taken:

Firstly, optimize total floor plan layout based on actual conditions at the factory site; secondly, implement temporary measures such as diversion routes for flow lines or bypass systems where necessary; thirdly, maintain regular maintenance schedules for equipment that cannot be shut down during construction periods