Abstract

At a paper manufacturing mill (PML) that had been previously part of an integrated pulp (bisulphite) and paper mills industry, cyanobacterial blooms were observed in the mill’s aerated stabilization basin (ASB) ponds at about 3 years after pulping had been discontinued. This study aimed to determine the factors that led to bloom occurrences and potential control strategies applicable to the paper manufacturing mill’s, aerated stabilization basin system that discharges wastewaters into a coastal lake. Following discontinuation of pulping, the colour of the wastewaters reduced to low levels (~ 10 Hazen units or less), while the levels of nutrient remained potentially supportive of cyanobacteria growth with total phosphorus at ~ 0.1 mg/L and total nitrogen at > 2.5 mg/L. Incidences of blooms in the ABS were associated with preceding average monthly rainfalls and wind speeds being less (~ 44% and ~ 7%, respectively) and average direct sunlight hours being greater (~ 9%) than the long-term average values. Zinc was investigated for control of cyanobacteria as this metal is less toxic to aquatic organisms and microflora than copper algaecides. In laboratory culture trials, zinc was found to inhibit growth of M. aeruginosa (strain MIC338) and Pseudanabaena sp. when dosed at ~ 2.5 mg/L. The inhibition of cyanobacteria by zinc was found to vary between ASB pond samples which had different in situ chlorophyll a levels. This study found that the PML wastewaters investigated can be supportive of cyanobacterial growth to bloom levels after discontinuation of pulping processes and that zinc has potential as a cyanobacteria control agent.

Graphic abstract

中文翻译：

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造纸废水中蓝藻水华的调查和锌作为控制剂的评估

摘要

在曾经是纸浆（亚硫酸氢盐）和造纸综合行业一部分的造纸厂（PML）中，制浆中断约三年后，在该厂的充气稳定池（ASB）池塘中观察到了蓝藻水华。这项研究旨在确定导致花开发生的因素和适用于造纸厂的充气稳定盆系统的潜在控制策略，该系统将废水排入沿海湖泊。制浆中断后，废水的颜色降低至较低水平（约10 Hazen单位或更少），而养分水平仍潜在地支持蓝细菌的生长，总磷为〜0.1 mg / L，总氮为> 2.5 mg /升 ABS中水华的发生与之前的平均月降雨量和风速小于（分别为〜44％和〜7％）以及平均日照小时数大于（长期）平均值有关（〜9％）。为了控制蓝细菌，人们对锌进行了研究，因为这种金属对水生生物和微生物区系的毒性比铜除藻剂低。在实验室培养试验中，发现锌可以抑制锌的生长。铜绿假单胞菌（MIC338菌株）和假单胞菌属。剂量约为〜2.5 mg / L时。发现锌对蓝细菌的抑制作用在具有不同原位叶绿素a水平的ASB池塘样品之间有所不同。这项研究发现，制浆过程中断后，所研究的PML废水可以支持蓝细菌的生长，使其达到水华水平，锌具有作为蓝细菌控制剂的潜力。

图形摘要