《深入打好城市黑臭水体治理攻坚战实施方案》的发布，让不少目光聚焦到了更为细致的地方，如：“建立健全垃圾收集(打捞)转运体系”，“不应盲目提高污水处理厂出水标准、新扩建污水处理... 《深入打好城市黑臭水体治理攻坚战实施方案》的发布，让不少目光聚焦到了更为细致的地方，如：“建立健全垃圾收集(打捞)转运体系”，“不应盲目提高污水处理厂出水标准、新扩建污水处理厂”，“到 2025 年，进水BOD 浓度高于 100 毫克/升的城市生活污水处理厂规模占比达90%以上”，“严格做好‘农家乐’、种植采摘园等范围内的生活及农产品产生污 水及垃圾治理”，“黑臭 水体整治不力问题纳入中央生态环境保护督察和长江经济带、黄河流域生态环境警示片现场调查拍摄范畴”， “落实污 水处理收费政策” ， “推广以 污 水处理厂进 水 污染物浓度、 污染物削减量 和 污泥 处置量 等支付 运营服务费”等等。
本文就这个问题来探讨一下。
什么是BOD
BOD，生化需氧量，指在一定条件下，微生物分解存在于水中的可生化降解有机物所进行的生物化学反应过程中所消耗的溶解氧的数量，是反映water中有机pollution含量的一个综合指标，也是重要的water quality pollution参数。
一般清净河流的五日生化需氧量不超过2mg/L，工业、农业、water use等要求生化需氧量应小于5mg/L，而life drinking water应小于1mg/L。《城镇pollution water treatment plant pollution material emission standard》修改单征求意见稿中明确,BOD5的一次监测最高允许排放浓度为①一级A15mg/L；一级B30mg/L②二级45mg/L③70mg/L.
为什么进water BOD低了不好
从上述定义看,BOD数值高就表明有机pollution含量高，不难理解为什么要关注进water BOD浓度的问题。但这里面还涉及一个核心问题，即清purification是否分流。如果没有分流，那么即使进water BOD较低，由于管网内大量沉积，有机材料仍可能导致下游排放依然不能达到国家规定标准，这就是为什么虽然我们说尽力降低进入生活饮用 water 的有机物质，但实际上还有许多其他因素需要考虑和解决.
从BDO看rain-pollution separation and pipe network expansion
专家普遍认为，大部分原因都可以归结到非-life pollution排入稀释，以及pipe network flow speed too low(BDO sediment in pipe network)这样的因素上，因此才会有"progress of BDO concentration"这样的关注点。这也是为什么我们提到的雨-pollution separation改造以及pipe network expansion改善都是非常关键的问题，它们直接关系到我们的生活饮用 water 的安全性。
这些措施包括但不限于：
Rain-pollution separation: This is a critical measure to prevent rain from mixing with waste, which would dilute the waste and reduce its effect on the environment.
Pipe Network Expansion: This involves expanding the existing pipe networks to accommodate more wastewater, reducing congestion and improving flow rates.
Upgrading Treatment Plants: To ensure that wastewater treatment plants can handle increased volumes of wastewater effectively.
By implementing these measures, we can significantly improve the quality of our life drinking water by reducing the amount of organic pollutants that enter it.
It's worth noting that "Fourteenth Five-Year Plan" for Urban Water Management has set a target to achieve a BDO level below 100 mg/l for all urban areas by 2025. This means that there will be a greater emphasis on improving sewerage systems, increasing investment in infrastructure development, and promoting sustainable practices in industries such as agriculture and construction.
In summary, while progress has been made towards achieving cleaner life drinking water through various initiatives such as rain-pollution separation and pipe network expansion, there is still much work to be done. By focusing on these key areas of improvement we can continue to make strides towards creating safer life drinking waters for all communities around us.
Confidence: 95%
标签： 基础地理
