New and Innovative Design of a Grit Chamber for Applications in Municipal Wastewater Treatment

污水处理的关键第一步是去除流入污水处理厂的无机砂砾。在加拿大，污水处理厂通常使用曝气砂砾室来去除砂砾，这需要在同一个腔室中产生两种不同的流动。需要高能湍流将有机涂层与重无机颗粒分离，需要静流使颗粒沉降。在同一个腔室中产生这些不同的流动条件在设计和操作方面都是非常困难的。这个问题可以通过在单独的腔室中执行这两项功能来解决，这将比现有的充气砂砾腔更高效，更经济。在加拿大，许多污水处理厂已经升级，通过增加二级和三级处理过程来达到国家排放标准，但没有修改其砂砾去除系统。因此，如果污水处理厂要能够处理随着城市和工业的发展而产生的越来越多的脂肪、油和油脂（FOG）和砂砾，就迫切需要对现有的砂砾去除系统进行升级。拟议的NSERC CRD计划将开发一种创新的砂砾室设计，该设计将比现有的砂砾室更高效，容量更大。建议增加一个配备交叉射流的预混合室，可以有效地将FOG从砂砾中分离出来，然后在下游沉降室中更有效地去除这些清洗过的砂砾。将进行中试试验，以确定预混室内产生大分散数的交叉射流构型和操作条件，以及产生大绝对速度梯度和均匀流场的操作条件。此外，将在金条污水处理厂进行实验，以确定新的除砂系统在处理实际废水时是否有效。本研究成果可直接应用于加拿大现有污水处理厂，提高除砂效率，提升整个污水处理工艺。

A crucial first step in the treatment of wastewater is the removal of inorganic grit from the influent to the wastewater treatment plant (WWTP). In Canada, WWTPs often use aerated grit chambers for grit removal and this requires the creation of two dissimilar flows in the same chamber. An energetic turbulent flow is required to separate organic coatings from the heavy inorganic grit particles, and a quiescent flow is required to allow settling of the grit particles. Generating these dissimilar flow conditions in the same chamber is very difficult in terms of both the design and operation. This problem can be solved by performing the two functions in separate chambers, which would be more efficient and cost effective than existing aerated grit chambers. In Canada, there are many WWTPs that have been upgraded to meet national effluent standards by the addition of secondary and tertiary treatment processes but with no modification of their grit removal systems. Therefore, upgrades to existing grit removal systems are urgently needed if WWTPs are to be able to cope with the increasingly large amounts of fat, oil and grease (FOG) and grit, associated with the growth of cities and industry. The proposed NSERC CRD Program will develop an innovative grit chamber design that will be more efficient and have larger capacity than existing grit chambers. The addition of a pre-mixing chamber equipped with cross-jets is proposed that will effectively separate FOG from grit and this cleaned grit can then be removed more efficiently in a downstream settling chamber. Pilot-scale experiments will be conducted to determine the cross-jet configuration and operating conditions that produce large dispersion numbers in the pre-mixing chamber as well as to determine the operating conditions that produce large absolute velocity gradients and homogeneous flow fields. Moreover, experiments at the Gold Bar WWTP will be performed to determine if the new grit removal system operates effectively when processing real wastewater. The proposed research results can be directly applied to existing Canadian WWTPs to improve grit removal efficiency and enhance the entire wastewater treatment process.