Final sewage effluent (FSE) is typically warmer than the rivers it is often discharged to. The excess heat energy could be recovered and utilised to help meet climate change targets. Using data from England for 2000–2019, we show that FSE temperatures were on average 2.2 °C higher than river temperatures, with a corresponding annual heat recovery potential of ∼18.3 TW h which could meet ∼3.6% of the UK's heat demand. Crude sewage temperatures were on average 1.5 °C higher that FSE temperatures, implying that a further ∼12.5 TW h is lost annually during treatment prior to discharge. The largest temperature differences between FSE and rivers, and crude sewage and FSE, occurred during the autumn and winter months, meaning that the greatest seasonal heat recovery potential coincides with the greatest heat demand. The temperature difference between FSE and rivers increased at an average rate of ∼0.03 °C per year from 2000 to 2019. Therefore, and in addition to predicted population growth, wastewater heat is a growing resource. The largest temperature differences between FSE and rivers would generally be expected to occur in northeast England. However, FSE discharges with sufficiently large temperature differences between FSE and rivers were demonstrated to exist across England and were not restricted to one region or water company. Wastewater treatment works discharge effluent continuously and occur nearby to domestic settlements, which account for the majority of the UK's heat demand. Therefore, there is clear local potential to recover heat and meet national emissions targets whilst further reducing environmental impact on rivers.

中文翻译：

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“废水”的热回收潜力：全国污水排放温度分析

最终污水流出物 (FSE) 通常比它经常排放到的河流温度更高。多余的热能可以回收和利用，以帮助实现气候变化目标。使用英格兰 2000-2019 年的数据，我们表明 FSE 温度平均比河流温度高 2.2°C，相应的年热回收潜力约为 18.3 TW h，可满足英国约 3.6% 的热量需求。粗污水温度平均比 FSE 温度高 1.5 °C，这意味着在排放前的处理过程中每年还会损失约 12.5 TW h。FSE 与河流、粗污水与 FSE 之间的最大温差发生在秋季和冬季月份，这意味着最大的季节性热回收潜力与最大的热量需求相吻合。从 2000 年到 2019 年，FSE 和河流之间的温差以每年约 0.03°C 的平均速度增加。因此，除了预测的人口增长外，废水热是一种不断增长的资源。FSE 和河流之间的最大温差通常预计发生在英格兰东北部。然而，FSE 和河流之间具有足够大温差的 FSE 排放被证明存在于整个英格兰，并且不仅限于一个地区或供水公司。污水处理厂不断排放污水，并发生在家庭居住区附近，这些居住区占英国热量需求的大部分。因此，当地有明显的潜力回收热量并实现国家排放目标，同时进一步减少对河流的环境影响。