环境科学 & 工程杂志. /21/18 | Seth Donrovich著


Since their introduction to North America in the mid-1980s, invasive zebra and quagga (dreissenid) mussels have been ravaging their newly adopted ecosystems. Dreissenid mussels have a high fecundity and ability to readily disperse due to their unique microscopic free-floating veliger (larva) life stage, causing rapid colonization of any water system they invade.

这些微小的软体动物已经严重破坏了生态系统, 抑制娱乐, and wreaked havoc on industries dependent on surface water for manufacturing or drinking and irrigation water. 事实上, 处理进气管的成本超过10年, 水过滤设备, and power plants’ operating costs for zebra mussel damages is estimated at $3.10亿美元.

同时有效地控制贻贝, chemical control options may be damaging to infrastructure, 出院前需要排毒, 需要重要的允许, 申请时间很长, and are toxic to non-target organisms and the environment. Mechanical control options are point-based and require a large upfront capital investment. Physical removal is likewise time-consuming and expensive.

Zequanox® molluscicide, commercially developed by Marrone生物创新公司., a provider of bio-based pest management and plant health products for the agriculture, 草坪及装饰及水处理市场, is the first fully biological control option specifically targeting invasive zebra and quagga mussels in all life stages. 作为生物控制, 对环境没有持久的影响, negligible effects on non-target organisms when used as directed, 以及工人的安全问题.

的活性成分 in Zequanox is composed of dead cells of the soil microbe, 荧光假单胞菌(Pf), which is ubiquitous in North American freshwaters and soils. Strains of Pf are commonly used in the manufacturing of food enzymes, 药品, 农业保护产品, 甚至在食物生产中. The Pf microbe in Zequanox is not genetically modified and is designated at Biosafety Level one, deeming it to be of the lowest possible risk to human health and the environment.

的活性成分, 结合生物, 食品级惰性, creates a wettable powder end product that has the appearance of freeze-dried coffee or granular cocoa powder. The formulated end product is mixed with on-site water to form a slurry which is then injected into the macrofouled water system. 不像化学控制选项, the invasive mussels respond to the Pf as a food source and will continue to filter feed in the presence of Zequanox, 有效的ly consuming the product along with their regular planktonic diet. Once ingested, the product will rupture the stomach lining of the mussels, causing mortality.

This unique mode of action allows for mortalities to occur over a period of time, 一般是几天到几周, which can prevent a massive shell-debris slug that could occlude, 例如, 关键系统热交换器. 本产品安全,使用方便, only requiring standard mixing and injection equipment and the use of basic personal protective equipment, e.g., eye protection and a dust mask, while mixing and loading the Zequanox when creating the slurry.

Zequanox是不锈的, 可生物降解的, 并且只需要2 - 6个小时的应用时间, therefore causing no disruption to normal facility operations. Treatments can help prevent unexpected outages and ensure continued system operation for industrial facilities. Waters treated with the product can be used immediately after application. In addition, there are no lasting effects to water quality and ecosystem health.

It is Pest 管理 Regulatory Agency (PMRA) registered for use in hydroelectric facilities in Canada, with both expanded enclosed system and open water registration packages submitted to PMRA in early 2018.

作为加拿大注册包的一部分, 并帮助将产品推向加拿大市场, a large-scale demonstration project occurred at Ontario Power Generation’s DeCew II Generating Station, 位于圣. 安大略的Catharines,在2009年到2012年之间.

During the final phase in a series of product efficacy trials in 2012, 对整个供水系统进行了处理, targeting full adult mussel control at high product concentrations. 采用生物盒评价产品的功效, which are small aquarium-like structures that receive treated system water, as a mesocosmic representation of the service water system. Zebra mussel mortality reached as high as 94% at 150 ppm of active ingredient concentration.

Significant improvements have been made to Zequanox since the early product implementation phase. 产品开发, 包括研究不同的治疗方案, has led to full mussel annual control being achieved with a lower active ingredient concentration of 100 ppm. 进行产品优化试验, this target concentration for full control can be reduced even further.

此外, 低浓度, frequent (every two to three weeks) maintenance treatments of 10 ppm active ingredient or less have been developed to target the settlement phase of the mussels, thereby preventing new mussels from attaching to surfaces within a water system.

This treatment program stems from the dreissenid mussel life cycle, which includes the approximate three week free-floating veliger stage, 在贻贝开始附着在固体表面之前. Treating over this settlement season not only limits the amount of new mussels in the system, but also steadily reduces the adult population over the duration of the treatment program. These maintenance programs can be customized based on the infestation level in a water system and the desired level of control. Regulations allow for up to 50 ppm of active ingredient concentration to be applied at a frequency of every two weeks for this treatment program.

This customizable maintenance program was commercially realized with eight, biweekly 低浓度 treatments occurring from June to October, 2017. This was designed to be conducted during a time period when the water temperature dictated high levels of mussel activity. This maintenance treatment program occurred at a power generation facility on the Great Lakes, which was experiencing both invasive zebra and quagga mussels in the once-through cooling system, 影响临界热交换器, including the surface condensers and boiler feedwater pump lube oil coolers.

Previous mussel control from thermal water circulation was prohibited due to recent permitting changes and the facility was searching for a safe, 有效的, and reliable solution to improve performance and reduce maintenance costs brought about by the mussel infestation. The facility chose Zequanox as a highly efficacious and environmentally friendly solution to their invasive zebra and quagga mussel issue.

在治疗过程中, Zequanox被计量进了系统, 分别分成两个单元(第七单元) & 8), for a period of two hours during normal facility operations. Therefore, the product application did not require any deviation from normal system operations. Product concentration was targeted at approximately 10 ppm of active ingredient for each of the treatments, with concentration regularly monitored throughout the application time.

类似于DeCew II的示范试验, bioboxes were used to determine the efficacy of the treatment program, with each unit having a biobox placed at a predetermined location downstream of the injection point. The biobox for unit 7 was placed at the approximate midpoint of the system, while the unit 8 biobox was placed near the terminus of the system. 在治疗过程中, cumulative adult mortalities indicated over 90% kill in the treated system collectively.

用8,0.125英寸厚,毛细胞ABS塑料板(4.375英寸x 4英寸), nested at a 15 degree angle on a clear acrylic base and placed perpendicular to the biobox flow to encourage settlement. In addition to the two treated bioboxes placed in units 7 and 8, an additional set of settlement plates was placed in a control biobox, located upstream of the injection point to monitor settlement in the absence of Zequanox.

在整个治疗过程中, the unit 7 biobox saw a 95% reduction in mussel settlement, 而8号生物箱则减少了52%.

The facility plans to continue their zebra and quagga mussel maintenance treatment program, ensuring fluid power generation and continuing to limit their maintenance costs.

A recent distributor partnership with Solenis LLC for enclosed water systems in Canada and the U.S. has made full service Zequanox treatments in industrial facilities as convenient as ever. Solenis将提供完善的客户服务, from designing treatment programs specific to the facility, 提供混合和注射设备, 进行现场申请, 监控, 和协商.

Further product optimization will not only continue to streamline enclosed industrial system treatment programs, but also tailor the product for use in both semi-enclosed and open water systems.

Seth Donrovich就职于马伦生物创新公司. 本文发表在ES上&E杂志2018年6月号.