在快速砂滤厂遇到的所有颗粒介质问题中，最显著的特点是问题发展所需的时间。媒体问题可能需要几个月甚至几年的时间才能显现出来。本文回顾了介质技术和设计的基础知识，并对六个案例进行了描述，这些案例涵盖了当今水处理厂运行中可能遇到的各种颗粒介质问题。然后，建议制定协议，以加强现有的过滤介质标准，避免或尽量减少介质安装以及水过滤设备运行和维护中常见和不常见的介质问题。课程包括固体分离（截留、沉淀、附着）；影响介质设计和性能的物理特征（固定床孔隙度、介质粒度、介质形状、介质密度、易碎性）； 反冲洗要求，包括空气冲刷；和媒体安排（多媒体、深床媒体）。案例研究包括过滤介质尺寸不当、双介质匹配不良、旧介质和长期磨损、结块介质和无烟煤分解、煤泥生长和单介质磨损、易碎性差和介质分解。列出了过滤介质、安装、操作和维护标准的推荐协议。

The most significant feature of all granular media problems encountered in rapid sand filter plants is the time it takes for a problem to develop. It may take months, or even years, before media problems become evident. The basics of media technology and design are reviewed along with descriptions of six case histories that, for all practical purposes, cover the gamut of granular media problems that may be encountered in the operation of water treatment plants today. Protocols are then recommended for strengthening present filter media standards and for avoiding or minimizing both common and uncommon media problems in the installation of media and in the operation and maintenance of water filtration plants. Topics covered include solids separation (entrapment, sedimentation, attachment); physical features affecting media design and performance (fixed bed porosity, media grain size, media shape, media density, friability); backwash requirements, including air scour; and media arrangements (multiple media, deep bed media). Case studies cover improper size of filter media, poor dual media match, old media and wear over time, caked media and anthracite breakdown, slime growth and single media wear, and poor friability and media breakdown. Recommended protocols for standards for filter media, installation, and operation and maintenance are listed.