Molecular biological methods to detect “Microthrix parvicella” and to determine its abundance in activated sludge

Molecular biological methods were evaluated in attempts to detect and quantitate levels of “Microthrix parvicella” in activated sludges. Approximately 66% of the 23S rRNA gene sequence of a strain (Ben43) of the Gram positive bulking and foaming organism “Microthrix parvicella” was determined, while a lesser amount was determined for “M. parvicella” strain RNI. The high mo1%G+C Gram positive bacteria (HGCGPBs) possess two powerfully diagnostic regions in the 23S rDNA and these were investigated in both strains. Firstly, the 18 nucleotide HGCGPB probe sequence (HGC69a) varied in at least two nucleotides with the sequence from both strains of “M. parvicella”. Secondly, an approximately 100 nucleotide stable insert between helices 54 and 55 in the 23S rRNA of HGCGPBs was discovered to be present in “M. parvicella”, but in both strains it was unique in length (79 nucleotides) and sequence. The region of the 23S rDNA with the stable insert was exploited to develop a polymerase chain reaction assay in which amplicons from “M. parvicella” were larger than those from nonHGCGPBs (i.e. all Bacteria except the HGCGPBs), and smaller than those from HGCGPBs. This assay was evaluated with DNAs extracted from activated sludges but although “M. parvicella” was morphologically identified, and was a dominant filament in at least one of the samples, no “M. parvicella” specific sized amplicons could be recovered from it. Amplicons of sizes generated by nonHGCGPBs and HGCGPBs were routinely produced in the stable insert PCR with DNAs from activated sludges where the highest yield was of amplicons from nonHGCGPBS.A second series of experiments were undertaken with the objective of evaluating the use of a non-radioactive hybridization method, based on extraction of bacterial RNA, for quantifying “M. parvicella” in activated sludge samples. Total nucleic acids were extracted from activated sludge samples and immobilized on nylon membranes. Probing with 16S rRNA-directed DIG-labelled oligonucleotide probes, detection of chemiluminescent signals on membranes and densitometry allowed hybridization signals to be quantified. The relationship between the amount of nucleic acid hybridized and the hybridization signal intensity observed was found to be linear over a specified range of signal intensities. A range of activated sludge samples were analysed for “M. parvicella” and variations in levels could be distinguished.     

Removal mechanisms of 17β-estradiol and 17α-ethinylestradiol in membrane bioreactors

The fate and behavior of natural and synthetic estrogens in wastewater treatment processes is currently of increasing concern all over the world. In this study, the removal mechanisms of a natural estrogen, 17β-estradiol (E2), and a synthetic estrogen, 17α-ethinylestradiol (EE2) were investigated in membrane bioreactors (MBRs) with and without powdered activated carbon (PAC) addition. The experimental results showed that the average removal rates of E2 and EE2 by the MBR without PAC addition were 89.0 and 70.9%; PAC addition in the MBR increased the removal rate of E2 and EE2 by 3.4 and 15.8%, respectively. The greater impact of PAC dosing on EE2 removal was due to its greater hydrophobic property. Adsorption played a more important role in the removal mechanisms of EE2 than E2. Biodegradation was the dominant mechanism for the removal of E2 and EE2 in MBRs. Unlike their adsorption behavior, the biodegradation rates of both E2 and EE2 were not significantly different between the MBRs with and without PAC addition.     

Fouling cake layer in a submerged anaerobic membrane bioreactor treating saline wastewaters: curse or a blessing?

The treatment of inhibitory (saline) wastewaters is known to produce considerable amounts of soluble microbial products (SMPs), and this has been implicated in membrane fouling; the fate of these SMPs was of considerable interest in this work. This study also investigated the contribution of SMPs to membrane fouling of the; (a) cake layer/biofilm layer, (b) the compounds below the biofilm/cake layer and strongly attached to the surface of the membrane, (c) the compounds in the inner pores of the membrane, and (d) the membrane. It was found that the cake/biofilm layer was the main reason for fouling of the membrane. Interestingly, the bacteria attached to the cake/biofilm layer showed higher biodegradation rates compared with the bacteria in suspension. Moreover, the bacteria attached to the cake layer showed higher amounts of attached extracellular polysaccharides (EPS) compared with the bacteria in suspension, possibly due to accumulation of the released EPS from suspended biomass in the cake/biofilm layer. Molecular weight (MW) analysis of the effluent and reactor bulk showed that the cake layer can retain a large fraction of the SMPs in the reactor and prevent them from being released into the effluent. Hence, while cake layers lead to lower fluxes in submerged anaerobic membrane bioreactors (SAMBRS), and hence higher costs, they can improve the quality of the reactor effluent.     

Numerical modelling: a tool for better constructed wetland design?

There is a need for a simplified computer-based design tool for subsurface flow constructed wetlands (CWs) which is based on process-based numerical models. Parameters of existing design guidelines and rules have been derived from experiments under specific conditions. Therefore designing CWs using these parameters is limited to these conditions (i.e., temperature, wastewater composition, filter material, etc.). Process-based numerical models describe the main processes in CWs in detail. If the design of CWs is based on these models it will be possible to design CWs for a variety of different boundary conditions and therefore the main limitation of existing design guidelines and rules could be overcome. The use of process-based models is currently limited mainly due to their complexity in structure and use. To make numerical modelling a useful and applicable tool for design, a simplified computer-based design tool that does not require special knowledge of numerical modelling is needed. Additionally, simple models for pre- and post-treatments are also required. Besides allowing designs for various boundary conditions, design tools based on process-based models can also predict the dynamic behaviour of the designed system thus showing e.g., the higher robustness of CWs against fluctuating inflows and peak loads compared to other treatment solutions. Such a tool could increase the quality of CW design and the acceptance and use of CW simulation in practice.     

Activated sludge foaming: What causes hydrophobicity and can it be manipulated to control foaming?

Activated sludge aeration tanks frequently suffer from the formation of a stable foam on their surfaces, a problem which results in increased operating costs and reduces performance. Current control strategies are often unsuccessful, mainly because of a lack of understanding of the microbes involved, and often employ expensive and environmentally undesirable procedures, such as the addition of chemicals. Here we have attempted to better understand the mechanism(s) involved in foam formation. We have investigated the possible relationship between the mycolic acid content in a Rhodococcus rhodochrous strain isolated from foam, its cell surface hydrophobicity (CSH) and ability to form stable foam. Results show that mycolic acid composition is not the only contributor to CSH, nor is the CSH the only factor responsible for foam formation and stabilisation. Other possible explanations for mechanisms of foaming and ways to control it are addressed.     

Clean development mechanism: a way to sustainable waste management in developing countries?

The Clean Development Mechanism established under the Kyoto Protocol allows investors in the developed world to invest in the developing world in return for emission credits. The CDM has two goals—to contribute to the reduction of emissions in the developed countries, and to promote sustainable development in the developing country. The objective of this paper is to analyze the project portfolio of 400 published CDM projects in the sector “waste handling and disposal” according to their project and technology characteristics.     

Let’s bring in the floods: de-poldering in the Netherlands as a strategy for long-term delta survival?

Controlled flooding, while heavily contested, is being experimented with in the Dutch delta as a new and ecologically oriented strategy to deal with floods, in contrast to the conventional flood prevention paradigm. The Noordwaard project (2012–15) represents an exemplary case. At the expense of agricultural practices, land is set aside occasionally to accommodate river floods, while restored flood and tidal dynamics aim to benefit nature development. It is argued that although controlled flooding aims to restore historical land and water dynamics in the area, the role of sedimentation processes has remained largely unaddressed in relation to shaping long-term delta futures.     

Strengthening the ‘bio’ in biome: Living river biomes as a concept to leverage public engagement for river health

This Perspective argues for an expansion of conventional concepts of river biomes to better encapsulate the emerging social understanding of ‘biomes’ as living systems with unique macro- and micro-biotic ecological and biological signatures. We approach this by firstly examining recent interpretations of river biomes that have evolved from original zonal conceptions. We then postulate on the social/public understanding on ‘biomes’ through the popularity of two rich debates: human health via gut microbiomes and soil health via the soil microbiome. With these concepts in mind, we define the river biome as ‘A living flowing aquatic ecosystem, indicative of its environmental context, comprising unique biological, ecological, hydrologic and health characteristics that shape and are shaped by macro- and micro-biotic signatures and functions’. With this definition the term river biome is more aligned with ideas of river health and ecosystem functioning, which we believe may evoke greater public understanding of rivers as complex living systems. Enhanced public understanding of complex natural systems should be encouraged as a means by which to propel policy, funding and research as well as to improve specialist to non-specialist communication and relations.     

Tourism as tragedy? Common problems with water in post-revolutionary Nicaragua

This paper examines the increased demand placed on limited water resources by a rapidly growing tourism sector in Playa Gigante, Nicaragua. Results from field campaigns suggest that recharge of the local aquifer may not meet burgeoning tourism demands for water. This paper also points to initial conflicts over water between locals and tourism operations, which are further complicated by ineffective implementation of national water policies and the common pool nature of groundwater. The conclusion discusses the need for more extensive research and better implementation of water policy through community governance and collaboration.     

Why doesn’t every family practice rainwater harvesting? Factors that affect the decision to adopt rainwater harvesting as a household water security strategy in central Uganda

ABSTRACT

This article investigates the reasons householders do, and don’t, adopt domestic rainwater harvesting (DRWH). Using a mixed-methods research approach, we collected data in three districts in central Uganda. Factors that emerged as important with respect to uptake of DWRH to address water shortage, especially at the household scale, include the work of intermediary organizations, finance mechanisms, life course dynamics and land tenure.     

Water Allocation as a Planning Tool to Minimise Water Use Conflicts in the Upper Ewaso Ng’iro North Basin, Kenya

Inadequate water resources management and a general decline in rainfall have aggravated water scarcity problems in the Upper Ewaso Ng’iro North Basin in Kenya. Furthermore, water use conflicts in the basin have escalated in recent decades due to increased competition for available water resources. Excessive abstraction of the declining river water mainly for irrigation in the Mount Kenya and Nyandarua foot zones often leads to reduced water flow during the dry seasons, greatly affecting downstream water users. Increased water use in the basin coupled with deterioration of the vegetative cover has resulted in reduced water flows in the Ewaso Ng’iro river and its major tributaries. In addition, lack of sufficient knowledge about available water resources and current lack of coordination in water resources management in the basin often result in water deficits which have hampered development in the downstream catchment. The goal of this study was to match the water requirements of various competing sectors in the basin with the available water resources in order to attain both economic and ecological sustainability. To achieve this, GIS techniques were used to quantify the spatial and temporal stream flow. The Water Evaluation and Planning (WEAP) model was applied to evaluate water resources development based on an equilibrium scenario of the current water demand. Water use was simulated for five different sectors (domestic, livestock, wildlife, irrigation and reserve). The analyses revealed that high water demand for irrigation was the main cause of excessive water abstraction particularly in the upstream catchments, giving rise to water shortages and consequently, water use conflicts downstream. The study, therefore, recommends that rainwater harvesting be promoted in the basin in order to improve water availability for productive use.     

Firms’ willingness to invest in a water fund to improve water-related ecosystem services in the Lake Naivasha basin,Kenya

A valuation scenario was designed using a contingent-valuation approach and presented to decision makers in business firms in Kenya’s Lake Naivasha basin to test how applicable a water fund might be as a potential financing mechanism for a payment for water-related ecosystem services scheme. The findings indicate that measuring a firm’s willingness to invest in ecosystem services could help determine whether a firm would invest and engage with other stakeholders to pool their investments in ecosystem services. Linking the institutional decision-making behaviour of a firm and its willingness to invest in a water fund is the novelty of this article.     

Can Fluctuating Asymmetry in Adult Burrowing Mayflies (Hexagenia rigida,Ephemeroptera) be used as a Measure of Contaminant Stress?

Fluctuating asymmetry (FA) in bilateral organisms may provide an early warning for detrimental effects of environmental stress in organisms well before populations are affected. Adult Hexagenia rigida were collected (17 June to 1 July 1996) at 6 sites around Lake Erie, representing areas with high (Monroe, MI; Colchester, ON; Middle Sister Island, ON) and low (Windsor, ON; Kingsville, ON; Catawba, OH) exposure to PCB contaminants. Balsam Lake, ON served as a reference site. Initially 27 structures were examined on the left and right sides of 30 males from both the most contaminated (Monroe) and least contaminated (Balsam Lake) sites using image analysis. Traits were autocorrelated; therefore, 7 independent traits were identified using principal component analysis. It was anticipated that there would be greater variation (i.e., greater FA) in organisms collected from sites known to exhibit high PCB body burdens than in organisms having low levels of contaminants. However, there were no significant differences in FA for male or female adults of H. rigida among the sites for the morphometric traits measured. There were significant differences in FA for two traits in H. rigida males among years (1991, 1994 to 96) at Windsor, but trends were not consistent. Although measurement error was low (1 to 6 %), results suggest that contaminant effects may be difficult to detect in the field because either the stress (PCBs) in the field was not strong enough to elicit a response by Hexagenia or PCB body burdens did not alter development in the insects.     

The role of groundwater in loading of nutrients to a restricted bay in a Precambrian Shield lake Part 2. – Numerical modeling

Previous modeling of hydrologic and nutrient budgets of lakes in Precambrian Shield regions have generally ignored groundwater as a source of water and supplier or sink of nutrients. This paper and its companion (Part 1) address this science gap by probing the role of groundwater in the nutrient balance for a restricted bay of a Precambrian Shield lake (Lake of the Woods) that experienced extensive shoreline development in the 1990s. Based on field data (Part 1), we applied a 3D reactive transport model (FEFLOW) to simulate the fate of nutrients in a cottage septic plume in groundwater and seepage into the bay. Corresponding simulations are for chloride and septic tracers in the plume, and 1D modeling of the mass balance of one septic tracer (acesulfame) in the bay. Our results suggest that, before they reach the lake, significant portions of the septic plume contaminants are attenuated by various processes, including uptake by transpiring plants. Extrapolating, we estimate that, for annual fluxes to the bay, groundwater seepage contributes ~1–3% of the phosphorus (P) and ~2–5% of the dissolved inorganic nitrogen (DIN). The results suggest that these groundwater nutrient fluxes to the bay are derived mainly from natural background sources. In contrast, cottage septic plumes contribute a quarter of the groundwater flux of DIN to Poplar Bay, while the septic contribution of P to the bay is negligible. We estimate that the largest sources of P and DIN fluxes to Poplar Bay are influx from the open lake and atmospheric deposition.     

Water–energy–food nexus in a transboundary context: the Euphrates–Tigris river basin as a case study

The interlinkage between water, energy and food security and its transboundary relevance is becoming increasingly important. The paper analyses the evolution of transboundary water resources management in the Euphrates–Tigris basin with specific reference to interlinkages between water, food and energy policies at national and transboundary levels, and it explores how the policy shifts at the highest decision-making level have served to produce synergies for cooperation among the riparians or vice versa.     

Lipid peroxidation in the freshwater shrimp Caridina nilotica as a biomarker of Roundup(?) herbicide pollution of freshwater systems in South Africa

Glyphosate-based herbicides used to control weeds and invading alien plant species in South Africa ultimately end up in freshwater ecosystems, but no South African environmental water quality guideline exists to regulate these bio-active chemicals. Ecotoxicological tests to assess the possibility of using lipid peroxidation (LPx) in Caridina nilotica as a potential biomarker of Roundup(?), a glyphosate-based herbicide, pollution were conducted. In two separate tests, 40 days post hatch shrimps were exposed to different concentrations of 4.3, 6.7, 10.5, 16.4, 25.6 and 40.0 mg/L in a 96 h acute toxicity test; and 2.2, 2.8, 3.4, 4.3 and 5.4 mg/L in a 21 d chronic toxicity test, using static-non renewal and static-renewal methods, respectively. Shrimp whole body LPx was estimated by thiobarbituric acid reactive species (TBARS) assay, performed by a malondialdehyde (MDA) reaction with 2-thiobarbituric acid (TBA) measured spectrophotometrically. Final MDA concentrations were expressed as nmol MDA produced/mg protein. Results showed that LPx was significantly lower in control animals than in animals exposed to different Roundup(?) concentrations, (p < 0.05). The present work provides an ecotoxicological basis for the possible use of LPx in Caridina nilotica as a biomarker for monitoring Roundup(?) pollution in freshwater ecosystems.     

The Afghan water law: “a legal solution foreign to reality”? 1

In this article the suggested permit and licence systems included in the draft Afghan Water Law of 2008 (superseding those laws of 1981 and 1991) are examined by comparing them with main canal data from two pilot studies within the Kunduz Basin. The comparison highlights the difficulty of making these proposed legal frameworks operative. Overall, it appears that the sections within the law on permits and licences are not implementable within or even useful for the traditional irrigation systems, but mainly play into the hands of the national hydrocracy and please international donors.     

Is Shallow Water a Suitable Surrogate for Assessing Efforts to Address Pallid Sturgeon Population Declines?

It is hypothesized that slow, shallow water habitats benefit larval pallid sturgeon Scaphirhynchus albus; however, testing this hypothesis is difficult, given the low number of larval pallid sturgeon present in large rivers. In contrast, relatively large numbers of age‐0 shovelnose sturgeon Scaphirhynchus platorynchus have been sampled, providing a potentially useful baseline to assess the importance of slow, shallow water to age‐0 sturgeon of both species (hereafter age‐0 sturgeon) in the lower Missouri River. Thus, we investigated the potential relationships between the prevalence of shallow water <1.5 m and the age‐0 sturgeon catch rates at multiple scales. Age‐0 sturgeon were usually sampled in water >1.5 m, and catch rates were usually highest in the upper half [i.e. river kilometre (RKM) 400 to 800] of the lower Missouri River study area, whereas the availability of water <1.5 m was usually highest in the lower half (i.e. RKM 0 to 400). Similarly, there was no relationship between age‐0 sturgeon mean catch‐per‐unit effort and ha/km of water <1.5 m at any studied scale. Our results may suggest that shallow water, as currently defined, may not be a suitable surrogate for assessing efforts to address pallid sturgeon population declines. However, it is still unknown if lack of appropriate habitat is currently limiting pallid sturgeon. Published 2015. This article is a U.S. Government work and is in the public domain in the USA. River Research and Applications published by John Wiley & Sons Ltd.     

Bioaccumulation of Inorganic Elements in Dreissena polymorpha from the Ebro River,Spain: Could Zebra Mussels Be Used as a Bioindicator of the Impact of Human Activities?

Dreissena polymorpha is among the top 100 most harmful invasive species in aquatic habitats. European Directive 2013/39/UE establishes Environmental Quality Standards for biota because it has been demonstrated that pollutants bioaccumulate in aquatic organisms. This study evaluated bioaccumulation of inorganic elements in the soft tissues of D. polymorpha in order to assess the usefulness of zebra mussels as a bioindicator of contaminant presence in superficial waters. Concentrations of 66 elements were measured in order to evaluate their relationship with nearby anthropogenic activity and to the values recommended by Environmental Quality Standards for biota. Bivalves were collected from four sample points along the Ebro River Basin (Spain), where diverse human activities are carried out. Zebra mussels accumulate toxins in soft tissue during their life cycle, including Al, Cr, Fe, Hg, Pb, Th, Cd and U. The highest levels of accumulation corresponded to elements associated with human activity in the area, showing the impact of anthropogenic actions on biota. D. polymorpha not only supplies information about current water quality but also acts as a witness of past water quality by bioconcentrating toxic elements present in the environment and providing relevant results about historical water contamination. In conclusion, D. polymorpha is a harmful and dangerous invasive species, but its pervasiveness means that it can be used as a bioindicator to assess current and past presence of elements in water. Copyright © 2017 John Wiley & Sons, Ltd.