Wastewater Treatment Works Research Articles

Phosphorus fluxes to the environment from mains water leakage: Seasonality and future scenarios

Accurate quantification of sources of phosphorus (P) entering the environment is essential for the management of aquatic ecosystems. P fluxes from mains water leakage (MWL-P) have recently been identified as a potentially significant source of P in urbanised catchments. However, both the temporal dynamics of this flux and the potential future significance relative to P fluxes from wastewater treatment works (WWT-P) remain poorly constrained. Using the River Thames catchment in England as an exemplar, we present the first quantification of both the seasonal dynamics of current MWL-P fluxes and future flux scenarios to 2040, relative to WWT-P loads and to P loads exported from the catchment. The magnitude of the MWL-P flux shows a strong seasonal signal, with pipe burst and leakage events resulting in peak P fluxes in winter (December, January, February) that are >150% of fluxes in either spring (March, April, May) or autumn (September, October, November). We estimate that MWL-P is equivalent to up to 20% of WWT-P during peak leakage events. Winter rainfall events control temporal variation in both WWT-P and riverine P fluxes which consequently masks any signal in riverine P fluxes associated with MWL-P. The annual average ratio of MWL-P flux to WWT-P flux is predicted to increase from 15 to 38% between 2015 and 2040, associated with large increases in P removal at wastewater treatment works by 2040 relative to modest reductions in mains water leakage. However, further research is required to understand the fate of MWL-P in the environment. Future P research and management programmes should more fully consider MWL-P and its seasonal dynamics, alongside the likely impacts of this source of P on water quality.

Wastewater-based epidemiology and enantiomeric profiling for drugs of abuse in South African wastewaters

The current study is aimed to introduce a wastewater-based epidemiology (WBE) approach for the first time on the African continent where substance abuse data is limited. The study included the quantification of several drugs of abuse (DOA) in raw wastewater samples. Quantification of urinary metabolites as drug target residues (DTR), as well as enantiomeric profiling of chiral DOA was performed to distinguish between consumption and direct disposal into sewage. Monitoring campaigns were undertaken at two South African wastewater treatment works (WWTWs) located within two provinces of the country. The presence of non-racemic 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine, as well as the metabolite of cocaine, benzoylecgonine (BEG), confirmed their consumption within the areas investigated. Enantiomeric profiling further pointed to the abuse of methamphetamine as the primary DOA with use estimates calculated between 181.9 and 1184.8mg·day−1·1000inhabitants−1. Population-normalised mass loads for MDMA and cocaine confirmed their status as secondary DOA within the study sites. Use estimates for the new psychoactive substance (NPS) mephedrone were performed for one WWTW. The minor metabolite of heroin, O-6-monoacetylmorphine (O-6-MAM), was also detected at one WWTW and served as a qualitative indicator for heroin abuse within the area. These findings provide a novel comparison of the WBE approach in a developing-country with other global studies, with the aim to strengthen this approach as a tool to inform drug prevention strategies in countries where substance abuse data is limited due to financial constraints and lack of government structures to facilitate conventional monitoring.

The brains of bats foraging at wastewater treatment works accumulate arsenic, and have low non-enzymatic antioxidant capacities

Increasing rates of urbanisation cause ubiquitous infrastructures that remove anthropogenic contaminants – particularly Wastewater Treatment Works (WWTWs) – to become stressed, and hence pollute surrounding water systems. Neoromicia nana bats are suitable models to study the effects of pollution in these environments because they exploit abundant pollutant-tolerant chironomid midges that breed at WWTWs, and consequently accumulate metals such as iron, copper and zinc in their livers and kidneys. If these metals persist in their circulatory systems, and cross the blood brain barrier (BBB) they can have adverse effects on critical functions such as flight and echolocation. The aim of this study was to investigate the potential neurological effects on N. nana foraging at WWTWs versus bats at reference sites in Durban, South Africa. Our objectives were to 1) compare trace metal levels in brain and hair samples (as a proxy for circulating metals) between N. nana foraging at WWTWs and reference sites to determine if excess metals pass through the BBB via the circulatory system; and 2) compare biomarkers of neuron function (acetylcholinesterase activity), protection (antioxidant capacity), DNA integrity (DNA fragmentation), lipid integrity (lipid peroxidation) and cell viability (caspase-3 activity) between N. nana foraging at WWTW and reference sites. We found a significantly higher concentration of arsenic in hair (p < 0.05) and brain tissue (p < 0.1) of WWTW bats compared to bats at reference sites. By contrast, acetylcholinesterase activity did not differ in bats among sites and there was no evidence of significant differences in lipid peroxidation, compromised DNA integrity or apoptosis in the brains between WWTW bats and reference site bats. However, total antioxidant capacity was significantly lower in brains of WWTW bats than bats at reference sites suggesting that antioxidant protection may be compromised. Long-term exposure to environmental pollutants at WWTWs may therefore affect cellular processes and protection mechanisms in brains of N. nana bats. It may also affect other mechanisms and functions in the brain such as mitochondrial efficiency and other neurotransmitters but that remains to be tested.

Occurrence and distribution of tetrabromobisphenol A and its derivative in river sediments from Vaal River Catchment, South Africa

Abstract Brominated flame retardants (BFRs) compounds have been widely added in a number of products to reduce their flammability. In the present study, the concentrations and distribution of tetrabromobisphenol A (TBBPA) and its derivatives, i.e. tribromophenol dibromopropyl ether (TBPDBPE), tetrabromobisphenol A bis-dibromopropyl ether (TBBPA BDBPE), tetrabromobisphenol A bis-allyl ether (TBBPA BAE) were investigated in sediment samples collected from the Vaal River catchment, South Africa. The results showed that all these pollutants were detected in sediments with TBBPA BAE being the most abundant contaminant. The TBBPA BAE concentrations ranged from 3.5 to 44.4 ng/g (mean 16 ng/g) while the concentration ranged from not detected (nd) to 2.4 ng/g (mean 0.6 ng/g), nd - 21.0 ng/g (mean 6 ng/g) and nd - 2.0 ng/g (mean 0.2 ng/g) for TBPDBPE, TBBPA and TBBPA BDBPE; respectively. Higher concentrations of these pollutants were found in sampling sites receiving effluents of wastewater treatment works (WWTWs) treating some industrial wastewater suggesting effluents might play an important role in the contamination of BFRs in the environment. Negative correlation between TBBPA and TBBPA BAE was observed implying different sources or environmental fates between these pollutants. Overall, the results showed a need for further studies to be undertaken in investigating the presence, fate and sources of alternative halogenated flame retardants in the environment.

Active pharmaceutical ingredients entering the aquatic environment from wastewater treatment works: A cause for concern?

This work reports on the variation in wastewater treatment works (WwTW) influent concentrations of a wide variety of active pharmaceutical ingredients (APIs), their removal efficiency, effluent concentrations and potential risks to the aquatic environment. The research is based on data generated from two large UK-wide WwTW monitoring programmes. Taking account of removal of parent compound from the aqueous phase during treatment in combination with estimates of dilution available it is possible to prioritise the APIs of greatest risk of exceeding estimates of predicted no effect concentrations (PNEC) in receiving waters for all WwTW in the UK. The majority of substances studied were removed to a high degree, although with significant variation, both within and between WwTW. Poorer removal (between influent and effluent) was observed for ethinyloestradiol, diclofenac, propranolol, the macrolide antibiotics, fluoxetine, tamoxifen and carbamazepine. All except the last two of these substances were present in effluents at concentrations higher than their respective estimated PNEC (based on measurement of effluents from 45 WwTW on 20 occasions). Based on available dilution data as many as 890 WwTW in the UK (approximately 13% of all WwTW) may cause exceedances of estimated riverine PNECs after mixing of their effluents with receiving waters. The overall degree of risk is driven by the toxicity value selected, which in itself is controlled by the availability of reliable and relevant ecotoxicological data and consequently the safety factors applied. The dataset and discussion, provides information to assist in the future management of these types of chemicals.

Euler-Lagrange Computational Fluid Dynamics simulation of a full-scale unconfined anaerobic digester for wastewater sludge treatment

For the first time, an Euler-Lagrange model for Computational Fluid Dynamics (CFD) is used to model a full-scale gas-mixed anaerobic digester. The design and operation parameters of a digester from a wastewater treatment works are modelled, and mixing is assessed through a novel, multi-facetted approach consisting of the simultaneous analysis of (i) velocity, shear rate and viscosity flow patterns, (ii) domain characterization following the average shear rate value, and (iii) concentration of a non-diffusive scalar tracer. The influence of sludge’s non-Newtonian behaviour on flow patterns and its consequential impact on mixing quality were discussed for the first time. Recommendations to enhance mixing effectiveness are given: (i) a lower gas mixing input power can be used in the digester modelled within this work without a significant change in mixing quality, and (ii) biogas injection should be periodically switched between different nozzle series placed at different distances from the centre.

Genetic characterization of &lt;i&gt;Salmonella&lt;/i&gt; and &lt;i&gt;Shigella&lt;/i&gt; spp. isolates recovered from water and riverbed sediment of the Apies River, South Africa

Riverbed sediment is a vital component of river ecosystems and plays an important role in many geomorphological and ecological processes. However, when re-suspension occurs, pathogenic bacteria associated with sediment particles may be released into the water column, thus creating a health risk to those who use such water for drinking, household and recreational purposes. The aim of this study was to investigate the presence of bacterial pathogens Salmonella spp. and Shigella spp. in the Apies River and to ascertain whether there was any level of genetic relatedness between river water and riverbed sediment isolates of these pathogenic bacteria. A total of 124 water and sediment samples were collected from a site located on the Apies Rivers upstream of the Daspoort Wastewater Treatment Works, Pretoria, Gauteng, South Africa, between August and November 2014. In order to detect and identify the target bacteria, samples were analysed by culture-dependent and culture-independent techniques (quantitative real-time PCR). Genetic relatedness was established using Sanger sequencing of the invA gene of Salmonella spp. and ipaH of Shigella spp. Results of this study displayed the presence of the target bacteria both in the water and sediment of the river. The phylogenetic tree of Salmonella spp. revealed a ≥ 99% and 99% genetic relatedness between river water and riverbed sediment isolates for Salmonella spp. and Shigella spp., respectively. The degree of genetic relatedness between sediment and water pathogen isolates suggests that these organisms could possibly have a common origin and that there could be possible movement of microorganisms between the water column and the sediments. Keywords: Salmonella spp., Shigella spp., river water, riverbed sediment, genetic relatedness

Developing and applying metamodels of high resolution process-based simulations for high throughput exposure assessment of organic chemicals in riverine ecosystems

As defined by Wikipedia (https://en.wikipedia.org/wiki/Metamodeling), “(a) metamodel or surrogate model is a model of a model, and metamodeling is the process of generating such metamodels.” The goals of metamodeling include, but are not limited to (1) developing functional or statistical relationships between a model's input and output variables for model analysis, interpretation, or information consumption by users' clients; (2) quantifying a model's sensitivity to alternative or uncertain forcing functions, initial conditions, or parameters; and (3) characterizing the model's response or state space. Using five models developed by the US Environmental Protection Agency, we generate a metamodeling database of the expected environmental and biological concentrations of 644 organic chemicals released into nine US rivers from wastewater treatment works (WTWs) assuming multiple loading rates and sizes of populations serviced. The chemicals of interest have log n-octanol/water partition coefficients (logKOW) ranging from 3 to 14, and the rivers of concern have mean annual discharges ranging from 1.09 to 3240m3/s. Log-linear regression models are derived to predict mean annual dissolved and total water concentrations and total sediment concentrations of chemicals of concern based on their logKOW, Henry's Law Constant, and WTW loading rate and on the mean annual discharges of the receiving rivers. Metamodels are also derived to predict mean annual chemical concentrations in fish, invertebrates, and periphyton. We corroborate a subset of these metamodels using field studies focused on brominated flame retardants and discuss their application for high throughput screening of exposures to human and ecological populations and for analysis and interpretation of field data.

A technological and economic exploration of phosphate recovery from centralised sewage treatment in a transitioning economy context

Phosphate is one of the substances which wastewater treatment works (WWTW) have to lower in order to meet the South African regulatory discharge standard of 1 mg/L. Wastewater is increasingly viewed as a ‘water-carried waste’, presenting opportunities for resource recovery. South Africa has commenced its transition to a low-carbon and resource-efficient economy, all whilst it struggles to provide universal access to basic needs and is faced with massive infrastructure maintenance as well as upgrading backlogs in the sanitation sector in particular. Although phosphate recovery methods exist, there is little evidence to indicate that these techniques would be economically viable or socially accepted in South Africa. This paper explores the potential for centralized recovery of nutrients, through the conceptual design and techno-economic pre-feasibility assessment of two phosphate recovery options, at the largest WWTW in the Western Cape, South Africa. This assessment revealed that the digestate stream at the 200 ML/d Cape Flats WWTW (CFWWTW) has the potential to produce ~470 kg/d of struvite fertilizer, whilst recovering 4–8% of the plant’s costs in 20 years. When contrasted with the more familiar, yet less sustainable, chemical precipitation process, low-grade and high-grade struvite production establishment costs are 10 and 25 times higher, respectively. Still, to reduce effluent phosphate loading to within regulated standards, the low-grade struvite production option at an estimated net present cost of R25.4 million over a 20-year lifetime is more affordable than chemical precipitation at a net present cost of R51.2 million. Low-grade struvite production is thus concluded to be technically feasible and the economically most affordable option from a lifecycle-costs perspective. Although it is a simple process, it is not cheap. Municipalities will need to consider the lower operating costs, as well as the environmental benefit of producing a useful phosphate fertilizer, over the immediate capital investment, if they decide to install such an operation.

Predictive framework for estimating exposure of birds to pharmaceuticals.

We present and evaluate a framework for estimating concentrations of pharmaceuticals over time in wildlife feeding at wastewater treatment plants (WWTPs). The framework is composed of a series of predictive steps involving the estimation of pharmaceutical concentration in wastewater, accumulation into wildlife food items, and uptake by wildlife with subsequent distribution into, and elimination from, tissues. Because many pharmacokinetic parameters for wildlife are unavailable for the majority of drugs in use, a read-across approach was employed using either rodent or human data on absorption, distribution, metabolism, and excretion. Comparison of the different steps in the framework against experimental data for the scenario where birds are feeding on a WWTP contaminated with fluoxetine showed that estimated concentrations in wastewater treatment works were lower than measured concentrations; concentrations in food could be reasonably estimated if experimental bioaccumulation data are available; and read-across from rodent data worked better than human to bird read-across. The framework provides adequate predictions of plasma concentrations and of elimination behavior in birds but yields poor predictions of distribution in tissues. The approach holds promise, but it is important that we improve our understanding of the physiological similarities and differences between wild birds and domesticated laboratory mammals used in pharmaceutical efficacy/safety trials, so that the wealth of data available can be applied more effectively in ecological risk assessments. Environ Toxicol Chem 2017;36:2335-2344. © 2017 SETAC.

The fate of pharmaceuticals and personal care products (PPCPs), endocrine disrupting contaminants (EDCs), metabolites and illicit drugs in a WWTW and environmental waters

A large number of emerging contaminants (ECs) are known to persist in surface waters, and create pressure on wastewater treatment works (WWTW) for their effective removal. Although a large database for the levels of these pollutants in water systems exist globally, there is still a lack in the correlation of the levels of these pollutants with possible long-term adverse health effects in wildlife and humans, such as endocrine disruption. The current study detected a total of 55 ECs in WWTW influent surface water, 41 ECs in effluent, and 40 ECs in environmental waters located upstream and downstream of the plant. A list of ECs persisted through the WWTW process, with 28% of all detected ECs removed by less than 50%, and 18% of all ECs were removed by less than 25%. Negative mass balances of some pharmaceuticals and metabolites were observed within the WWTW, suggesting possible back-transformation of ECs during wastewater treatment. Three parental illicit drug compounds were detected within the influent of the WWTW, with concentrations ranging between 27.6 and 147.0 ng L−1 for cocaine, 35.6–120.6 ng L−1 for mephedrone, and 270.9–450.2 ng L−1 for methamphetamine. The related environmental risks are also discussed for some ECs, with particular reference to their ability to disrupt endocrine systems. The current study propose the potential of the pharmaceuticals carbamazepine, naproxen, diclofenac and ibuprofen to be regarded as priority ECs for environmental monitoring due to their regular detection and persistence in environmental waters and their possible contribution towards adverse health effects in humans and wildlife.

Effects of nanosized titanium dioxide (TiO2) and fullerene (C60) on wastewater microorganisms activity

This paper investigates the impact of nano-TiO2 and fullerene (C60) on the activity of micro-organisms present in wastewater treatment works (WWTWs). Results showed that low concentration levels of nano-TiO2 (10μgL−1) and fullerene (1μgL−1) has little effect on both gas production and the microorganisms’ morphology. However higher concentrations of nano-TiO2 (100 and 1000μgL−1) and fullerene (10 and 100μgL−1) reduced or stopped completely gas production. SEM micrographs showed that addition of nanoparticles reduced the microorganisms count up to 30min of exposure, followed by an increase of selected micro-organisms after a 360min exposure to TiO2 and Fullerene. Overall, this study demonstrates that engineered nanoparticle concentration levels and exposure time play an important role in the toxicity of microbial communities present in WWTWs. It also shows that under stressed conditions, the micro-organisms appear to protect themselves via a spore forming mechanism that allows them to survive the environment.

Carbon curves for the assessment of embodied carbon in the wastewater industry

AbstractThe water and wastewater industry has been tasked with reducing its greenhouse gas (or carbon) emissions. A key component of any emissions reduction strategy is emissions measurement. While operational emissions are reported by the sector on an annual basis, there is a lack of robust data on embodied carbon. The aim of this paper was to develop a practical solution for assessing the embodied carbon in wastewater assets. The analysis revealed a linear relationship between carbon emissions and capital investment in the construction of wastewater treatment works (1.3 tCO2/£1000) and wastewater pumping stations (0.3 tCO2/£1000). Carbon emissions from sewer construction were found to increase linearly with increasing pipe diameter, with ductile iron pipelines responsible for higher emissions than polyethylene. Operational carbon is the major component in the whole life carbon of wastewater treatment works, but future decarbonisation of the electricity grid may increase the relative importance of embodied carbon.

Disruption of the Prostaglandin Metabolome and Characterization of the Pharmaceutical Exposome in Fish Exposed to Wastewater Treatment Works Effluent As Revealed by Nanoflow-Nanospray Mass Spectrometry-Based Metabolomics.

Fish can be exposed to a complex mixture of chemical contaminants, including pharmaceuticals, present in discharges of wastewater treatment works (WwTWs) effluents. There is little information on the effects of effluent exposure on fish metabolism, especially the small molecule signaling compounds which are the biological target of many pharmaceuticals. We applied a newly developed sensitive nanoflow-nanospray mass spectrometry nontargeted profiling technique to identify changes in the exposome and metabolome of roach (Rutilus rutilus) exposed to a final WwTWs effluent for 15 days. Effluent exposure resulted in widespread reduction (between 50% and 90%) in prostaglandin (PG) profiles in fish tissues and plasma with disruptions also in tryptophan/serotonin, bile acid and lipid metabolism. Metabolite disruptions were not explained by altered expression of genes associated with the PG or tryptophan metabolism. Of the 31 pharmaceutical metabolites that were detected in the effluent exposome of fish, 6 were nonsteroidal anti-inflammatory drugs but with plasma concentrations too low to disrupt PG biosynthesis. PGs, bile acids, and tryptophan metabolites are important mediators regulating a diverse array of physiological systems in fish and the identity of wastewater contaminants disrupting their metabolism warrants further investigation on their exposure effects on fish health.

Influence of composite particle formation on the performance and economics of grit removal

Grit is routinely removed at the headworks of municipal wastewater treatment works to limit its onerous impact on downstream processes. Grit separation technologies are normally based on sedimentation of a homogeneous material (usually sand). However, in practice inorganic grit particles are likely to be combined with organic matter, such as fats oils and grease (FOG), producing a composite particle whose settling properties vary with the inorganic/organic content.A study of the impact of particle composition on its sedimentation has been conducted encompassing theoretical description (for particle settling in transitional flow), practical measurement and economic analysis. Practical measurement included sedimentation tests of homogeneous and composite particles along with characterisation of accumulated granular material sampled from actual municipal wastewater treatment works. The economic assessment was based on data from full-scale installations in the UK and US pertaining to remedial measures undertaken as a result of grit impacts, primarily accumulation in vessels and channels and damage of mechanical equipment through abrasion.Practical tests revealed coating of the sand grains with a FOG analogue (candlewax) to generate composite particles containing 45% wax by weight. The coated particles were then 30% less dense, 22% larger and 14% less settleable, on average, than the uncoated particles. Samples of accumulated grit taken from anaerobic digesters and aeration lanes from a full-scale plant indicated a FOG content (43%) similar to that of the waxed particles in the bench-scale tests, thus leading to a similar grain retardation of 14% assuming the FOG to be entirely associated with the grit. An assessment of the impact of the consequential breakthrough of grit particles due to buoyancy generated by composite particle formation indicated a $1.1 increase in operating costs per megalitre (ML) wastewater.

Prevalence of pathogenic microorganisms and their correlation with the abundance of indicator organisms in riverbed sediments

The present study investigated the prevalence of pathogenic organisms (Salmonella spp, Vibrio cholerae, and Shigella spp) and their correlation to the abundance of faecal indicator organisms in water and riverbed sediments in the Apies River, South Africa. In all, 558 water and sediment samples were collected from 10 sites in the river (May 2013–February 2014) and analysed through culture and molecular (real-time PCR) techniques. Concentrations of faecal indicator organisms in sediments reached 1.39 × 105 (±standard deviation) CFU/100 mL. All three pathogens were detected in water and sediments. Pathogens were mostly detected in sediments at sites influenced either by wastewater treatment works or by informal settlements. During the wet and dry seasons (water column), a strong positive correlation was observed between E. coli and all pathogens; C. perfringens only correlated with V. cholerae. Within sediments, strong positive correlations were only observed between E. coli and Salmonella spp, E. coli and V. cholerae (dry season); E. coli and V. cholerae and E. coli and Shigella spp (wet season). No correlation was observed between sediments C. perfringens counts and all the pathogens. Thus, sediments of the Apies River harbour pathogenic organisms. Correlation between E. coli and pathogenic organisms in the sediments suggests that E. coli could also be an indicator of pathogens’ presence. However, the lack of a correlation between E. coli and some pathogens in sediments and between C. perfringens and all the pathogens highlights the need to investigate for more indicators of pathogens’ presence in this complex matrix.

Significance of Vivianite Precipitation on the Mobility of Iron in Anaerobically Digested Sludge

Anaerobic digestion requires a balanced availability of micro-nutrients with ideal growth conditions to reach optimal organic degradation and biogas production. Iron is the most abundant of the essential metals in an anaerobic digester and its mobility has a strong impact on microorganisms through its own bioavailability, but also through its influence on the bioavailability of other metals. Most previous research on iron mobility in anaerobic digestion has focused on sulfide as the controlling anion because digesters traditionally are sulfide rich and phosphate poor. However, chemical phosphorus removal (CPR) at wastewater treatment works (WWTW) can elevate phosphate concentrations in the digester 10-fold or more. The goal of this research was hence to examine the accepted wisdom of iron-sulfide dominance prevailing in all anaerobic digesters and by evaluating the potential for iron phosphate formation in municipal digesters treating CPR sludge. To fulfil this aim, iron compounds were identified experimentally from full-scale digesters at WWTW with CPR and the most likely iron species identified through modelling according to their thermodynamic probability of formation under the specific environmental conditions experienced in each anaerobic digester. Experimental and modelling data were then combined to identify the main chemical reactions controlling iron mobility in those anaerobic digesters. Results show that speciation of iron in the sampled anaerobic digesters was controlled by the solid phase through a primary reaction (sulfide precipitation to form pyrite and ferrous sulfide) and secondary reaction (phosphate precipitation to form vivianite). However, iron-sulfide precipitates represented only 10-30% of the total iron in the sampled digesters, while iron-phosphate precipitates represented more than 70%. The significance of the high quantity of vivianite in these digesters is that phosphate-rich anaerobic digesters will be more iron-mobile environments than sulfide-rich digesters, with iron being more readily exchanged between the solid and liquid phases during digestion, implying a higher level of bioavailability and the tendency to interact more readily with organic and inorganic counterparts.

A proposed assessment index for climate change-related risk for cultural heritage protection in Newcastle (Australia)

Worldwide, climate change is one of the main factors exacerbating the effects of hazards or generating additional risk. Investigation is required to understand climate change-related risks for all components of human systems, including cultural heritage. Accordingly, this paper aims to present a new risk assessment index for cultural heritage, referred to as the Cultural Heritage Risk Index (CHRI). The paper applies a desk-based review of the existing literature on climate change-related risks for cultural heritage and of multi-level policy and planning documents of cultural heritage management in Australia. The paper then presents the CHRI and describes its attributes based upon the formalisation of risk as a function of hazard, exposure and vulnerability. CHRI is applied to a unique asset of cultural heritage in Newcastle (Australia), the Burwood Beach Wastewater Treatment Works (BBWTW). The paper shows that this asset has a moderate risk related to climate change, and that some interventions can be applied to decrease its vulnerability. The use of a new index such as CHRI allows creating a baseline for the exploration of the relations between climate change-related risks and cultural heritage. It can be an effective part of tools assessing climate change-related risk on cultural heritage in Australia and might aid in prioritising specific interventions.

Searching for indigenous anaerobic ammonium oxidizing (anammox) bacteria in South African habitats: Pretoria region

ABSTRACTIn South Africa, the information about the distribution and activity of anaerobic ammonium oxidizing (anammox) bacteria is very limited and anammox systems have not yet been tested and implemented. In this study, the existence and diversity of the anammox bacteria from various South African habitats are investigated. Batch systems were used to enrich anammox biomass from sludge collected from three Pretoria municipal wastewater treatment works. Anammox activity was tested and detected in two of the three wastewater treatment works after 90 days of primary enrichment. The activity was confirmed by consumption of both NH4 + and NO2 − in the system. The presence of anammox bacteria was also confirmed by polymerase chain reaction (PCR) amplification of the 16s rRNA of the anammox using anammox-specific primers. All clones retrieved were closely related to Brocadia species and were most abundant in all habitats tested. The maximum growth rate of anammox was also estimated on both experiments using a relatively new model.

Reuse of redundant gravels and phyto-conditioned sewage sludge

Blackburn Meadows is one of the largest waste water treatment works and landfills under Yorkshire Water’s operation. The site treats sewage from over 450 000 people and produces more than 20 000 t of sludge annually, which requires disposal. The sewage sludge is disposed of by means of a number of methods, including incineration followed by landfilling of the ash and direct disposal to landfill. Between 2010 and 2014, the construction and restoration of landfills on the site required approximately 6000 m3 of gravels and 18 000 m3 of topsoil. This paper describes two sustainable examples of material recycling – redundant filter bed gravels from another local site were crushed for reuse in landfill construction and sewage sludge after in situ phyto-conditioning was reused for landfill restoration. Atkins designed the requirements for the reused materials to achieve the most cost-effective specification, which resulted in cost savings of more than 48% for the basal leachate drainage blanket and more than 79% for the restoration layer. Phyto-conditioned sewage sludge is demonstrated to be supporting vegetation on the restored landfills. The construction and restoration of landfills at Blackburn Meadows provided an outlet for approximately 24 000 m3 of materials that would otherwise require disposal by other means.