The use of a hybrid Sequential Biofiltration System for the improvement of nutrient removal and PCB control in municipal wastewater

This article aims to evaluate the efficiency of an innovative hybrid Sequential Biofiltration System (SBS) for removing phosphorus and nitrogen and polychlorinated biphenyls (PCBs) from original municipal wastewater produced by a Wastewater Treatment Plant under authentic operating conditions. The hybrid SBS was constructed with two barriers, a geochemical (filtration beds with limestone, coal and sawdust) and a biological barrier (wetlands with Glyceria, Acorus, Typha, Phragmites), operating in parallel. Significant differences were found between inflow and outflow from the SBS with regard to wastewater contaminant concentrations, the efficiency of removal being 16% (max. 93%) for Total Phosphorus (TP), 25% (max. 93%) for Soluble Reactive Phosphorus (SRP), 15% (max. 97%) for Total Nitrogen (TN), 17% (max. 98%) for NO3 –N, and 21% for PCB equivalency (PCB EQ). In the case of PCB EQ concentration, the highest efficiency of 43% was obtained using beds with macrophytes. The SBS removed a significant load of TP (0.415 kg), TN (3.136 kg), and PCB EQ (0.223 g) per square meter per year. The use of low-cost hybrid SBSs as a post-treatment step for wastewater treatment was found to be an effective ecohydrological biotechnology that may be used for reducing point source pollution and improving water quality

Bacterioplankton communities affect toxigenic Microcystis bloom – from environmental to laboratory study

Particle-attached bacteria are key biotic factors influencing the development of bloom-forming cyanobacteria dominated with toxigenic Microcystis. Therefore, knowledge about their ecological interactions (synergistic or antagonistic), niche occupancy, and co-occurrence patterns during different bloom developmental stages, and the looking for of autochthonous strains for cyanobacterial regulation, are essential. The aim was to describe bacterioplankton dynamics and their functional potential, including their influences on cyanobacteria and water quality, at the Sulejów Reservoir, Poland (Central Europe). Subsequently, bacteria with algicidal properties against Microcystis were isolated and characterized. Nitrogen-transforming proteobacterial taxa performing nitrogen fixation, nitrification, and denitrification, dominated at the beginning of summer. Then, in mid-summer, during mixed cyanobacterial bloom of Snowella, Aphanizomenon, and Microcystis, bacterial diversity significantly decreased, with higher domination of parasites/predators that fed on cyanobacteria. The post-summer was significantly dominated by toxigenic microcystin-producing Microcystis, which drove the highest negative impact on particle-attached bacteria. Despite this, Microcystis was associated with taxa feeding on their cells - Vampirovibrionales, and decaying exudates, including microcystin - Sphingobacteriales_env.OPS17, Sutterellaceae, and Anhiella. Parallelly, strains belonging to Bacillales, Exiguobacterales, Pseudomonadales, Enterobacteriales, Rhizobiales, and Xanthomonadales were isolated from the monitored reservoir, capable to lyse toxigenic M. aeruginosa cells in laboratory studies. Research funded: National Science Centre 2019/33/B/NZ8/02093 ALGICYD

Polyphasic toxicological screening of Cylindrospermopsis raciborskii and Aphanizomenon gracile isolated in Poland

Aphanizomenon gracile and Cylindrospermopsis raciborskii are extensively studied Nostocales of wide geographical distribution and have potential to produce toxins. However, a number of knowledge gaps regarding their toxicity and related health risks in certain locations, including Europe, exists. The present study applied a polyphasic approach to screen the toxicity of different strains of C. raciborskii (LBY-Cr, LBO-Cr and LKM-Cr) and A. gracile (LBY-Ag, LBN-Ag and LWI-Ag) isolated from five freshwater lakes of Western Poland. The following investigations were carried out: (i) in vitro toxicological studies employing human cells isolated from healthy donors; (ii) analytical screening for the presence of cylindrospermopsin (CYN), guanidinoacetate (GAA; initial CYN precursor and postulated general cyanobacterial metabolite), three microcystin (MC) analogues, β-N-methylamino-L-alanine (BMAA) and its isomer α-γ,-diaminobutyric acid (DAB), anatoxin-a (ATX) and ten saxitoxin (STX) analogues; and (iii) molecular studies of genes involved in CYN, GAA, MCs and ATX biosynthesis. Extracts of C. raciborskii LBY-Cr and A. gracile LBN-Ag caused a significant increase in the intracellular reactive oxygen content in human neutrophils during short-term (1 h) exposure and also led to lipid peroxidation and cell death. No cytotoxic effects were noted for the other tested strains. None of the toxin genes (cyrA, cyrJ, anaF and mcyE) and toxins (CYN, GAA, MCs, BMAA, ATX and STX) were detected. The only exception was DAB found at a concentration below 1.0 μg g− 1 dw in A. gracile LWI-Ag. It is the first time that cyanobacterial DAB producer has been identified in the Central European region. The study points to the production of as yet unknown metabolite(s) that may pose a relevant threat to human health through strains of C. raciborskii and A. gracile isolated from two Polish lakes, and adds to the general understanding of the toxicity of European strains of both species

Relationships among cyanobacteria, zooplankton and fish in sub-bloom conditions in the Sulejow Reservoir

The occurrence of cyanobacteria is particularly characteristic of shallow eutrophic waters, and they often form massive ‘blooms’ that can affect aquatic invertebrates and fish. However, even a low abundance of cyanobacteria can be hazardous to aquatic organisms, due to the production of toxic metabolites. The aim of this study was to investigate the relationship between cyanobacteria and their toxicity (biological activity) towards zooplankton and fish communities, when only low concentrations of cyanobacterial chlorophyll a (less than 20 μg L-1) are detected, i.e. in sub-bloom conditions. Measurements were performed in Sulejow Reservoir (Central Poland), a shallow, lowland, eutrophic reservoir, in which cyanobacterial blooms occur regularly. Fish were assessed using echo-sounding (distribution) and by gillnetting (species composition). Simultaneously, zooplankton, cyanobacteria and physico-chemical characteristics were studied at 14 stations situated along hydroacoustic transects. Parameters that characterized the cyanobacteria (cyanobacterial chlorophyll a concentration, the number of 16S rRNA and the mcyA gene copies and microcystin (MC) concentration) were consistently correlated (based on a principal component analysis), and the highest values were found in the downstream region of the study area. This ‘cyano-complex’ was also positively correlated with oxygen concentration, pH and phosphate levels, but was negatively correlated with temperature and the concentrations of nitrates and nitrites. In Sulejow Reservoir in 2013 the biomass of large zooplankton filter feeders decreased along with increasing MC concentration and fish densities, while small filter feeders did not present such relationships with regards to fish densities. Fish abundance tended to decrease at stations with a lower abundance of cyanobacteria and with growing toxic genotype copies and MC concentration.</p