鱼和熊掌可以得兼——《平衡好藻类繁殖控制和消毒副产物控制之间的关系》

原文链接：

https://awwa.onlinelibrary.wiley.com/doi/epdf/10.1002/opfl.1620

原文作者：

PETER S. FISKE

原文出处：J Opflow

翻译：阮辰旼

Balancing Harmful Algal Bloom Control and Disinfection Byproduct Formation

平衡好藻类繁殖控制和消毒副产物控制之间的关系

Campbell, Ohio, which lies along the Mahoning River, is a manufacturing town with a rich history. Situated outside of Youngstown, Campbell was the site of steel manufacturing at the turn of the 20th century and had diversified its economy with light manufacturing.

俄亥俄州的坎贝尔，位于马霍宁河畔，是一个具有悠久历史的制造业重镇。坎贝尔位于扬斯镇郊外，曾是钢铁制造业的所在地，并在20世纪初通过轻工制造业实现了经济的转型。

Drinking water for Campbell's 8,200 residents is supplied from a single lime-softening plant that draws its water from nearby Hamilton Lake. After coagulation with sodium aluminate, lime softening removes calcium and magnesium ions. Flocculation and clarification followed by dual-media filtration results in high-quality finished water that's then chlorinated and distributed to the town. The plant produces 1 mgd on average, with pH usually around 9.5.

坎贝尔8200名居民的饮用水由一个石灰软水处理厂供应。该厂从附近的汉密尔顿湖取水，在投加硫酸铝混凝剂后，用石灰软化可去除钙和镁离子，再通过絮凝和澄清，并通过双介质的过滤，得到高质量的出厂水，经过氯化消毒后后输配到该镇。该水厂平均生产1百万加仑/天，pH值通常在9.5左右。

With an increased occurrence of harmful algal blooms (HABs) in the region's lakes, the Campbell Water team has maintained a vigilant approach to water quality. When the Ohio Environmental Protection Agency issued new guidance in 2016 for reducing microcystin through increased chlorination, Campbell Water Facility Superintendent Joe Tovarnak increased chlorination to ensure microcystin destruction.

随着该地区湖泊中有害藻类水华（HABs）发生率的增加，坎贝尔水务团队一直对水质的情况保持高度的警惕。当俄亥俄州环境保护局在2016年发布通过增加加氯量来降低微囊藻毒素的新操作指南时，坎贝尔水务设施主管Joe Tovarnak便增加了加氯量，以确保微囊藻毒素的去除。

“We always erred on the side of ensuring complete destruction of microcystin,” he says. “Microcystin always seemed like the worse evil.”

Joe Tovarnak说：“微囊藻毒素看上去似乎是非常糟糕的恶魔，但我们在确保完全去除微囊藻毒素时采取的方法也总是再犯着错误。”

Unfortunately, in solving the microcystin problem, Campbell faced another challenge: trihalomethanes (THMs), which are formed when chlorine reacts with naturally occurring organic compounds in raw water. The US Environmental Protection Agency's Stage 2 Disinfectants and Disinfection Byproducts Rule mandates that water systems maintain a locational running annual average (LRAA) of no more than 80 μg/L. THM levels in the Campbell distribution system could get as high as 100 μg/L during the third quarter of some years. However, with the additional chlorination to combat microcystin, THMs spiked to 125 μg/L in one distribution system sample.

不幸的是，在解决微囊藻毒素的问题时，坎贝尔公司同时面临另一个挑战：三卤甲烷（THMs），它是在氯与水中自然存在的有机化合物反应时生成的。美国环境保护总署的第二阶段消毒剂和消毒副产物规则规定，供水系统必须保持运行年平均值（LRAA）不超过80微克/升。而实际上在某些年份的第三季度，坎贝尔供水系统中的三卤甲烷含量可能高达100微克/升。而且，在特别为了去除微囊藻毒素而额外强化进行氯消毒的过程中，在某个输配系统的水样中三卤甲烷一度飙升至125微克/升。

The Campbell Water team attacked the simultaneous challenge of microcystin and THMs with two different approaches. To lower microcystin levels in its raw water, Tovarnak hired Akron, Ohio–based Fontus Blue (www.fontusblue.com) to develop a comprehensive HAB management plan for Hamilton Lake and an optimization software tool for treating microcystin at the plant. This tool, called HAB-ALERT, allows operators to calculate the ideal treatment strategy for microcystin as a function of a variety of water treatment and plant operational parameters.

坎贝尔水务团队用了两种不同的方法同时应对微囊藻毒素和三卤甲烷的挑战。为了降低其原水中的微囊藻毒素水平，Joe Tovarnak聘请了俄亥俄州阿克伦市的Fontus Blue公司为汉密尔顿湖量身制定一个全面的有害藻类水华（HABs）管理计划和一个优化软件工具，用于水厂处理微囊藻毒素的工艺管理。这个被称为HAB-ALERT的工具，能够帮助运行人员计算出各种供水产工艺和运行人员操作的参数，以形成微囊藻毒素的理想工艺处理策略。

But implementing microcystin treatment while keeping THMs under control continued to be a delicate balancing act. In 2019, Tovarnak sought the help of the software firm once again—this time, to develop a comprehensive treatment strategy designed to optimize treatment for microcystin and THMs simultaneously. The Campbell Water team discovered Fontus Blue could help it solve both problems.

但在对微囊藻毒素进行工艺去除的的同时要保持对三卤甲烷生成的控制，仍然需要维持一个微妙的平衡。2019年，Joe Tovarnak再次寻求软件公司的帮助，这一次，时需要开发一个综合的处理策略，旨在同时优化微囊藻毒素的去除效果和三卤甲烷的抑制。坎贝尔水务团队认为Fontus Blue公司可以帮助其同时解决这两个问题。

Fontus Blue's Ashley Bair, a PhD candidate at the University of Akron, worked with the Campbell Water team to develop and calibrate a computer model that would accurately predict microcystin removal rates at the plant as well as THM production rates in the distribution system. Bair also trained the Campbell Water team to use UV-254 analysis to precisely measure organic levels in the raw water to better optimize chlorination and improve the efficiency of powdered activated carbon (PAC) to lower organic levels in the raw water. According to Tovarnak, Campbell Water was using PAC as the main way to adjust organic levels and lower THMs in the system.

Fontus Blue公司毕业于阿克伦大学的博士生Ashley Bair与坎贝尔水务团队合作，开发并校准完成了一个计算机模型，可以准确模拟出水厂的微囊藻毒素去除率以及输配系统中的三卤甲烷生成率。Ashley Bair还培训坎贝尔水务团队使用UV-254分析法精确测量原水中的有机物含量，以更好地优化加氯消毒过程，以及更好地提高粉末活性炭的效率，达到降低原水中的有机物含量的目的。据Joe Tovarnak说，坎贝尔水务公司正在使用粉末活性炭作为控制有机物含量和降低供水系统中三卤甲烷的主要方法。

“[PAC] is an effective solution, but it's expensive,” he says.

Joe Tovarnak说：“粉末活性炭是一个有效的解决方案，但它很昂贵。”

Fontus Blue's optimization tool, called THMMAX, was installed in Campbell Water's system in 2019. Unlike standard spreadsheets developed to support operators, HAB-ALERT and THMMAX are hosted on the cloud and run 24-7-365 to simulate and optimize water treatment parameters. THMMAX estimates THM levels in water distribution systems with a custom algorithm that factors in organic levels, chlorine dose, temperature, and other parameters. Operators input water quality parameters and can test the effectiveness of different combinations of chlorination, PAC, and other treatment processes using the computer software before they make any adjustments.

Fontus Blue公司给出的新的优化工具，称为THMMAX，于2019年部署在Campbell 水务的系统中。与传统的单纯为了支持运营商工作而开发的标准电子表格不同，HAB-ALERT和THMMAX都部署在云端，365天全天候不间断地模拟和优化水处理工艺参数。THMMAX通过一个定制的算法可以预估输配系统中的三卤甲烷水平，该算法同时考虑了有机物含量、加氯量、温度和其他参数。水厂运行人员只需要输入实时的水质参数，在不做任何其他操作之前，就可以使用计算机软件预估氯消毒、粉末活性炭工艺和其他处理过程之间不同组合的有效性。

Campbell had been close to the THM compliance limit for several quarters and even exceeded the limit at one site. Beginning in early 2020, operators were trained on UV-254 measurement and interpretation. Along with other water quality data, they entered the values into the software tool and tracked the impact on THM formation potential. By understanding the risk, operators could then make informed decisions on chemical dosing to improve organics removal, on pH, and on chlorine dose. Campbell immediately began seeing the positive results with a decrease in THM LRAAs at both testing sites for every successive quarter. In the fourth quarter of 2020, the Campbell Water team recorded the lowest LRAAs in plant history (Figure 1).

过去几个季度以来，坎贝尔水务公司的水质数据一直贴近三卤甲烷的合规性限值，甚至在一个采样点上超出了限值。从2020年初开始，运行人员接受了UV-254分析法（精确测量原水中的有机物含量）的培训，与其他水质数据一起，他们将检测到的实测数值输入软件工具并跟踪工艺对三卤甲烷形成潜力的影响。通过了解三卤甲烷生成的风险，运行人员可以在加药量方面做出明智的决定，以提高有机物的去除率、控制pH值和加氯量。此后，坎贝尔水务公司立即开始看到了积极的结果，两个采样点的三卤甲烷运行年平均值（LRAA）连续几个季度都在减少。在2020年第四季度，坎贝尔水务公司的三卤甲烷实测值创历史最低（图1）。

The facility's best results have come from implementing HAB-ALERT and THMMAX together. Given that during some parts of the year the Campbell Water team sees increases in microcystin and THMs, the software tools have enabled the utility to optimize PAC dosing for both THMs and microcystin, keeping both under control.

该案例所取得的优异成果得益于同时应用了HAB-ALERT和THMMAX软件工具。由于在一年中的某些时候，坎贝尔水务团队观察到了微囊藻毒素和三卤甲烷的增加，这些软件工具使该公司能够优化粉末活性炭投加量，有效控制三卤甲烷生成和微囊藻毒素去除，使两者都得到了控制。