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The use of persulfate oxidation processes is receiving increasing interest for the removal of aquatic contaminants. However, it is unknown whether its application in the presence of iodide has the potential to directly form iodinated DBPs. This study investigated formation of six chlorinated, brominated and iodinated di-haloacetamides (DHAcAms) during persulfate oxidation in the presence of bromide and iodide. Formation of the same DHAcAms during chlorination was monitored for comparison. Persulfate oxidation of natural water formed diiodoacetamide (DIAcAm), and heat-activated persulfate, at 45 °C and 55 °C, generated bromoiodoacetamide (BIAcAm) and dibromoacetamide (DBAcAm), besides DIAcAm. At an ambient iodide concentration of 0.3 μM, total DHAcAms increased slightly from 0.43 to 0.57 nM as the water temperature increased from 4 °C to 35 °C, respectively (only DIAcAm detected), then significantly increased to 1.6 nM at 55 °C (DIAcAm, BIAcAm and DBAcAm detected). Equivalent total DHAcAm concentrations in the presence of 3.0 μM iodide were 0.5, 0.91 and 2.1 nM, respectively. Total DHAcAms formed during chlorination, predominantly dichloroacetamide (DCAcAm) and bromochloroacetamide (BCAcAm), were always significantly higher than that during persulfate oxidation. However, an integrated risk assessment showed the toxicity resulting from the DHAcAms was higher during persulfate oxidation than chlorination. An increase in water temperature from 25 °C to 55 °C significantly increased the integrated toxic risk values for both persulfate oxidation and chlorination. Use of persulfate oxidation should be weighed against the formation of high-toxicity iodinated HAcAms in waters with high ambient iodide concentrations.

Persulfate oxidation processes, with and without activation using ultraviolet light (respectively UV/PS and PS) have the potential to degrade anthropogenic chemicals in water. However, little is known about the impact of PS or UV/PS pre-oxidation on downstream formation of disinfection by-products (DBPs). In this study the three antibiotic chloramphenicols (chloramphenicol and two of its analogues [thiamphenicol and florfenicol], referred to collectively as CAPs), which frequently occur in wastewater-impacted source waters used by drinking water treatment plants, were selected as model antibiotic compounds. The formation of carbonaceous and nitrogenous disinfection by-products, including halomethanes, haloacetonitriles and halonitromethanes, during chlorination and chloramination preceded by PS and UV/PS was investigated. No significant concentrations of haloacetonitriles and halonitromethanes were detected during chlorination. During chloramination chloramphenicol formed a considerable amount of dichloronitromethane (e.g., 3.44 ± 0.33% mol/mol at NH2Cl dose = 1 mM) and trichloronitromethane (e.g., 0.79 ± 0.07% mol/mol at NH2Cl dose = 1 mM), compared with THM and HAN formation. PS pre-oxidation achieved a statistically significant reduction in trichloromethane formation from chlorination, and in HAN and HNM formation from chloramination. Although UV/PS slightly increased dichloroacetonitrile formation during chloramination, it significantly decreased dichloronitromethane and trichloronitromethane formation during chloramination. Overall, the use of PS and UV/PS has the potential to have contrasting impacts on DBP formation in heavily wastewater-impacted waters, depending on the disinfection method. Hence, their application needs to be carefully balanced against the downstream effect on DBP formation.

Disinfection by-products (DBPs) in drinking water, including trihalomethanes (THMs) and haloacetic acids (HAAs), arise from reactions of natural organic matter (NOM) with chlorine and other disinfectants. The objective of this review was to investigate relationships between the molecular properties of NOM surrogates and DBP formation using data collated for 185 compounds. While formation of THMs correlated strongly with chlorine substitution, no meaningful relationships existed between compound physicochemical properties and DBP formation. Thus non-empirical predictors of DBP formation are unlikely in natural waters. Activated aromatic compounds are well known to be reactive precursors; in addition DBP formation from β-dicarbonyl, amino acid and carbohydrate precursors can be significant. Therefore effective DBP control strategies need to encompass both hydrophobic and hydrophilic NOM components, as well as consider data from NOM surrogates in the context of knowledge from representative treatment scenarios. In future experiments, employing surrogates of NOM is likely to remain a powerful tool in the search for unknown precursors and in understanding their response to various disinfection conditions.

In recent years research into the formation of nitrogenous disinfection by-products (N-DBPs) in drinking water - including N-nitrosodimethylamine (NDMA), the haloacetonitriles (HANs), haloacetamides (HAcAms), cyanogen halides (CNX) and halonitromethanes (HNMs) - has proliferated. This is partly due to their high reported toxicity of N-DBPs. In this review paper information about the formation yields of N-DBPs from model precursors, and about environmental precursor occurrence, has been employed to assess the amount of N-DBP formation that is attributable to known precursors. It was calculated that for HANs and HAcAms, the concentrations of known precursors - mainly free amino acids are insufficient to account for the observed concentrations of these N-DBP groups. However, at least in some waters, a significant proportion of CNX and NDMA formation can be explained by known precursors. Identified N-DBP precursors tend to be of low molecular weight and low electrostatic charge relative to bulk natural organic matter (NOM). This makes them recalcitrant to removal by water treatment processes, notably coagulation, as confirmed by a number of bench-scale studies. However, amino acids have been found to be easier to remove during water treatment than would be suggested by the known molecular properties of the individual free amino acids.

In the informal settlements of eThekwini municipality, South Africa, laundry activities are typically undertaken at local standpipes and washbasins of community ablution blocks (CABs), and are characterised by high levels of water consumption and greywater production. Since greywater contains a high pollution load, including sodium tripolyphosphate, it poses a significant environmental and public health risk. The overall objective of this study was to develop and test a water-efficient laundry system designed for informal settlements. Initial fieldwork at a standpipe and CAB in eThekwini municipality showed respectively 56 and 58% of users were in favour of a water-efficient laundry system based upon sharing washing water. Subsequent laboratory work assessed crosscurrent and countercurrent cascades for washing clothes. Under optimised washing conditions at a detergent dose of 5 g/kg water, specific water consumption of 5 kg water/kg clothes and three rinsing phases it was determined that the countercurrent method wasted 33% less water. Thus the countercurrent cascade has great potential for minimising greywater production in South African informal settlements. Future work should concentrate on evaluating greywater production, detergent usage and social acceptability in the field.

Anaerobic digestion is increasingly being considered as a treatment option for an extensive range of waste biomass, due to the potential for energy recovery, in the form of methane production, and lower sludge volumes relative to aerobic treatment processes. Furthermore, when two substrates are codigested (i.e. digested together), added benefits are foreseeable, such as increased methane production and detoxification of toxic compounds via cometabolic degradation pathways. The objectives of this study were to compare experimental and predicted methane production from codigestion literature studies in order to objectively evaluate digester performance. Two predictive methods were used, both assuming methane yields are additive: literature values for digestion of single substrates and a stoichiometric method using model substrates to represent different substrates. Waste sources included in the analysis were primary sewage sludge, waste activated sludge, cow manure, waste paper, grease trap sludge, fat oil and grease and algal sludge. It was found that methane production could approximately be predicted using both methods, with literature methane yields from the same study being the most accurate predictor. One important finding from this study was that the assumption that methane yields are additive is a reasonable one. Furthermore, both predictive methods may be usefully employed as a screening tool to compare methane yields between different types and blends of substrates.

Technologies which recover biogas do so by harnessing anaerobic degradation pathways controlled by a suite of microorganisms. The biogas released acts as an environmentally sustainable energy source, while providing a method for disposal of various wastes. Biogas contains 50–70% methane and 30–50% carbon dioxide, as well as small amounts of other gases and typically has a calorific value of 21–24 MJ/m3. Various appliances can be fuelled by biogas, with stoves offering an application appropriate for deployment in developing countries. Widespread dissemination of biogas digesters in developing countries stems from the 1970s and there are now around four and 27 million biogas plants in India and China respectively. These are typically small systems in rural areas fed by animal manure. However, in many other countries technology spread has foundered and/or up to 50% of plants are non-functional. This is linked to inadequate emphasis on maintenance and repair of existing facilities. Hence for biogas recovery technology to thrive in the future, operational support networks need to be established. There appear to be opportunities for biogas stoves to contribute to projects introducing cleaner cookstoves, such as the Global Alliance for Clean Cookstoves. Beyond this, there remains potential for domestic plants to utilise currently underexploited biogas substrates such as kitchen waste, weeds and crop residues. Thus there is a need for research into reactors and processes which enable efficient anaerobic biodegradation of these resources.

While natural organic matter (NOM) surrogates are established in disinfection byproduct (DBP) research, their use in fractionation studies is rare. To understand how surrogates relate to drinking waters, a range of NOM surrogates were fractionated with XAD resins. Their trihalomethane (THM), haloacetic acid (HAA), haloacetaldehyde, haloacetonitrile, and haloketone formations after chlorination were recorded. While compounds with higher log K(ow) values behaved as hydrophobic acids, fractionation of the more hydrophilic compounds did not clearly correlate to the log K(ow). High HAA formation from ferulic and aspartic acids and 1,1,1-trichloropropanone (1,1,1-TCP) formation from 3-oxopropanoic acid were notable. Three amino acids, asparagine, aspartic acid, and tryptophan, formed significant levels of dichloroacetonitrile (DCAN) and trichloroacetaldehyde (TCA). Formation of DBPs did not correlate to any compound physical property; however, there were several correlations between DBP groups. The most significant were between dichloroacetic acid (DCAA) and dichloroacetonitrile (DCAN), DCAN and TCA, and dichloroacetaldehyde (DCA) and trichloroacetaldehyde, indicating the possibility of similar relationships in natural waters.

Formation of disinfection by-products (DBPs) can be controlled by removal of disinfection by-product precursors before disinfection. Variable success has been reported, depending on the treatment used and water tested. Chemical and biological oxidations are candidate technologies to control DBP formation. Given the uncertainty over the identity of DBP precursors, the use of surrogates of natural organic matter (NOM) allows fundamental probing of the links between compound character, removal and DBP formation. Nine compounds were chosen to represent NOM and their removal by two advanced oxidation processes (AOPs), UV-C irradiation and biological treatment compared while haloacetic acid (HAA) formation before and after treatment was measured. Although AOPs were able to fully remove all compounds, incomplete mineralisation led to increased HAA levels, dramatically in the case of two amino acids. Biological treatment was effective in removing amino acids but also moderately increased the HAA formation potential (HAAFP) of hydrophilic compounds. These findings indicate waters with high amino acid concentrations will be susceptible to raised HAA levels following AOP treatment and careful process selection for HAA control is required in such cases.

Low-molecular weight organic acids (LMWOAs) are widespread in nature, and many are recalcitrant during conventional drinking water treatment, due to their LMW and hydrophilic character. This study assessed the formation of a range of disinfection by-products (DBPs) from the chloramination of seven non-nitrogenous LMWOA precursors, with an emphasis on the contribution of N-chloramine incorporation to haloacetamide (HAcAm) formation. The other DBPs comprised chlorinated halomethanes, haloacetonitriles and haloacetic acids. Citric acid generated higher yields of trichloromethane and two chloroacetic acids than the other LMWOAs. Further, the unsaturated acids (fumaric acid and itaconic acid) formed more chloroacetic acids than saturated acids (oxalic acid, succinic acid, adipic acid). Importantly, non-nitrogenous LMWOAs formed three nitrogenous DBPs (dichloroacetamide, trichloroacetamide, and small amounts of dichloroacetonitrile) during chloramination, firstly indicating the monochloramine can supply the nitrogen in nitrogenous DBPs, and the formation of haloacetamides at least in part is independent of the hydrolysis of haloacetonitriles. To the authors’ knowledge, this is the first time formation of halogenated nitrogenous DBPs (N-DBPs) has been reported from chloramination of non-nitrogenous LMWOA precursors. This indicates that concentrations of dissolved organic nitrogen compounds in drinking water are not a reliable surrogate for formation of N-DBPs during chloramination. Bromine incorporation factor increased with increasing bromide during chloramination of citric acid, and bromine was easier to incorporate into di-HAcAms than mono- and tri-HAcAms during chloramination.

Despite the recent focus on nitrogenous disinfection byproducts in drinking water, there is limited occurrence data available for many species. This paper analyses the occurrence of seven haloacetonitriles, three haloacetamides, eight halonitromethanes and cyanogen chloride in 20 English drinking water supply systems. It is the first survey of its type to compare bromine substitution factors (BSFs) between the haloacetamides and haloacetonitriles. Concentrations of the dihalogenated haloacetonitriles and haloacetamides were well correlated. Although median concentrations of these two groups were lower in chloraminated than chlorinated surface waters, median BSFs for both in chloraminated samples were approximately double those in chlorinated samples, which is significant because of the higher reported toxicity of the brominated species. Furthermore, median BSFs were moderately higher for the dihalogenated haloacetamides than for the haloacetonitriles. This indicates that, while the dihalogenated haloacetamides were primarily generated from hydrolysis of the corresponding haloacetonitriles, secondary formation pathways also contributed. Median halonitromethane concentrations were remarkably unchanging for the different types of disinfectants and source waters: 0.1 μg·mgTOC(-1) in all cases. Cyanogen chloride only occurred in a limited number of samples, yet when present its concentrations were higher than the other N-DBPs. Concentrations of cyanogen chloride and the sum of the halonitromethanes were not correlated with any other DBPs. The Department for Environment, Food and Rural Affairs (Defra) and the Drinking Water Inspectorate (DWI) for England and Wales are gratefully acknowledged for funding this work, as part of project DWI 70/2/268.

Sustainable methods are required in developing regions to treat and recover value from pit latrine sludge. One potential strategy is to pyrolyse pit latrine contents and generate char and bio-oil, which can then be used as a soil enhancer and fuel, respectively. Despite the many benefits associated with the process, there is very limited relevant literature available. This study examines its feasibility. Initially, the energy balance associated with pyrolysis of sewage sludge was calculated using data from 14 literature studies. For dewatered sewage sludge, the average energy input required during drying and pyrolysis 2.9 ± 0.2 MJ kg−1 sludge, while the average net energy recovered from combustion of bio-oil was 6.9 ± 0.2 MJ kg−1. For sewage sludge which had been dewatered and dried prior to pyrolysis equivalent values were 1.2 ± 0.2 MJ kg−1 and 8.5 ± 0.9 MJ kg−1. Parallel calculations were then undertaken with pit latrine sludge as the hypothetical feedstock, assuming a water content of 30, 52, 82 or 97% wt. The energy input required was 2.1, 2.6, 3.3 and 3.6 MJ kg−1, respectively. Corresponding net energy recoveries from pyrolysis combined with use of the resultant bio-oil as fuel were 9.7 ± 0.8, 7.1 ± 0.8, 6.5 ± 0.8 and 6.1 ± 0.8 MJ kg−1. Char production is more favorable from stabilised pit latrine sludge with lower moisture and volatile solids content. Barriers to pyrolysis of pit latrine sludge are discussed, including the heterogeneity of pit latrine composition and the difficulty of collecting high-viscosity sludge. Overall, this study demonstrates the potential that pyrolysis has as a disposal and value addition method for pit latrine sludge. Innovative methods for sludge drying and pit emptying will expedite the process becoming a reality.

Many scientific studies have suggested that point-of-use water treatment can improve water quality and reduce the risk of infectious diseases. Despite the ease of use and relatively low cost of such methods, experience shows the potential benefits derived from provision of such systems depend on recipients' acceptance of the technology and its sustained use. To date, few contributions have addressed the problem of user experience in the post-implementation phase. This can diagnose challenges, which undermine system longevity and its sustained use. A qualitative evaluation of two household water treatment systems, solar disinfection (SODIS) and chlorine tablets (Aquatabs), in three villages was conducted by using a diagnostic tool focusing on technology performance and experience. Cross-sectional surveys and in-depth interviews were used to investigate perceptions of involved stakeholders (users, implementers and local government). Results prove that economic and functional factors were significant in using SODIS, whilst perceptions of economic, taste and odour components were important in Aquatabs use. Conclusions relate to closing the gap between factors that technology implementers and users perceive as key to the sustained deployment of point-of-use disinfection technologies.

This study investigated the relative effect of chlorination and chloramination on DBP formation from seven model amine precursor compounds, representative of those commonly found in natural waters, at pH 6, 7 and 8. The quantified DBPs included chloroform, dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN) and chloropicrin (trichloronitromethane). The aggregate formation (i.e. the mass sum of the formation from the individual precursors) of chloroform, DCAN and TCAN from all precursors was reduced by respectively 75–87%, 66–90% and 89–93% when considering pre-formed monochloramine compared to chlorine. The formation of both haloacetonitriles decreased with increasing pH following chlorination, but formation after chloramination was relatively insensitive to pH change. The highest formation of chloropicrin was from chloramination at pH 7. These results indicate that, while chloramination is effective at reducing the concentrations of trihalomethanes and haloacetonitriles in drinking water compared with chlorination, the opposite is true for the halonitromethanes.

The objective of this research was to develop lightweight cement mortars with good thermal-insulation properties by incorporating expanded polystyrene (EPS) and paper sludge ash (PSA), both of which are problematic waste materials. The mortars formed had low thermal conductivity and low bulk density compared to control samples. Ground EPS produced lower thermal conductivity samples than powdered EPS. Resource efficient mortars containing up to 20% PSA, and 60% of EPS are considered suitable for use in rendering and plastering applications. The authors wish to thank the Spanish Ministry of Science and Innovation and European Union (FEDER) for project funding (BIA2007-61170), and the FPI scholarship (BES-2009-012166) award to Verónica Ferrándiz Mas which allowed her to develop her doctoral thesis. This research was carried out in the Civil and Environmental Engineering Department at Imperial College London, with funding from the Spanish Ministry of Economy and Competitiveness (EEBB-I-12-0574) to support Verónica Ferrándiz Mas.

Ozonation before chlorination is associated with enhanced formation of chloropicrin, a halonitromethane disinfection by-product (DBP), during drinking water treatment. In order to elucidate reasons for this, five natural organic matter (NOM) surrogates were treated using both chlorination and ozonation–chlorination under controlled laboratory conditions. Selected surrogates comprised two phenolic compounds, two free amino acids and one dipeptide; these were resorcinol, 3-aminophenol, L-aspartic acid, β-alanine and ala-ala, respectively. Quantified DBPs included chloropicrin, chloroform, dichloroacetonitrile and trichloroacetonitrile. Relative to chlorination alone, increases in the formation of chloropicrin from ozonation–chlorination varied from 138% for 3-aminophenol to 3740% for ala-ala for the four amine surrogates. This indicates that ozone is more effective than chlorine in mediating a rate-limiting oxidation step in chloropicrin formation, most plausibly involving conversion of an amine group to a nitro group. While both hydrophilic and hydrophobic surrogates acted as chloropicrin precursors, ala-ala was the most reactive precursor following ozonation–chlorination. Since peptides are far commoner in drinking water sources than free amino acids, further research into chemical oxidation of these species by ozone and chlorine is recommended. In contrast, oxidation with ozone prior to chlorination reduced chloroform formation moderately for the two phenolic compounds.

During drinking water treatment aqueous chlorine and bromine compete to react with natural organic matter (NOM). Among the products of these reactions are potentially harmful halogenated disinfection by-products, notably four trihalomethanes (THM4) and nine haloacetic acids (HAAs). Previous research has concentrated on the role of bromide in chlorination reactions under conditions of a given NOM type and/or concentration. In this study different concentrations of dissolved organic carbon (DOC) from U.K. lowland water were reacted with varying amounts of bromide and chlorine in order to examine the interrelationship between the three reactants in the formation of THM4, dihaloacetic acids (DHAAs) and trihaloacetic acids (THAAs). Results showed that, in general, molar yields of THM4 increased with DOC, bromide and chlorine concentrations, although yields did fluctuate versus chlorine dose. In contrast both DHAA and THAA yields were mainly independent of changes in bromide and chlorine dose at low DOC (1 mg·L(-1)), but increased with chlorine dose at higher DOC concentrations (4 mg·L(-1)). Bromine substitution factors reached maxima of 0.80, 0.67 and 0.65 for the THM4, DHAAs and THAAs, respectively, at the highest bromide/chlorine ratio studied. These results suggest that THM4 formation kinetics depend on both oxidation and halogenation steps, whereas for DHAAs and THAAs oxidation steps are more important. Furthermore, they indicate that high bromide waters may prove more problematic for water utilities with respect to THM4 formation than for THAAs or DHAAs. While mass concentrations of all three groups increased in response to increased bromide incorporation, only the THMs also showed an increase in molar yield. Overall, the formation behaviour of DHAA and THAA was more similar than that of THM4 and THAA.

The idea of implementing ancient water and wastewater technologies in the developing world is a persuasive one, since ancient systems had many features which would constitute sustainable and decentralised water and sanitation (WATSAN) provision in contemporary terminology. Latest figures indicate 2.6 billion people do not use improved sanitation and 1.1 billion practise open defecation, thus there is a huge need for sustainable and cost-effective WATSAN facilities, particularly in cities of the developing world. The objective of this study was to discuss and evaluate the applicability of selected ancient WATSAN systems for the contemporary developing world. Selected WATSAN systems in ancient Mesopotamia, the Indus Valley, Egypt, Greece, Rome and the Yucatan peninsula are briefly introduced and then discussed in the context of the developing world. One relevant aspect is that public latrines and baths were not only a part of daily life in ancient Rome but also a focal point for socialising. As such they would appear to represent a model of how to promote use and acceptance of modern community toilets and ablution blocks. Although public or community toilets are not classified as improved sanitation by WHO/UNICEF, this is a debatable premise since examples such as Durban, South Africa, illustrate how community toilets continue to represent a WATSAN solution for urban areas with high population density. Meanwhile, given the need for dry sanitation technologies, toilets based on the production of enriched Terra Preta soil have potential applications in urban and rural agriculture and warrant further investigation.

Formation of harmful disinfection by-products (DBPs), of which trihalomethanes (THMs) and haloacetic acids (HAAs) are the major groups, can be controlled by removal of natural organic matter (NOM) before disinfection. In the literature, removal of precursors is variable, even with the same treatment. The treatment of DBP precursors and NOM was examined with the intention of outlining precursor removal strategies for various water types. Freundlich adsorption parameters and hydroxyl rate constants were collated from the literature to link treatability by activated carbon and advanced oxidation processes (AOPs), respectively, to physico-chemical properties. Whereas hydroxyl rate constants did not correlate meaningfully with any property, a moderate correlation was found between Freundlich parameters and log K(ow), indicating activated carbon will preferentially adsorb hydrophobic NOM. Humic components of NOM are effectively removed by coagulation, and, where they are the principal precursor source, coagulation may be sufficient to control DBPs. Where humic species remaining post-coagulation retain significant DBP formation potential (DBPFP), activated carbon is deemed a suitable process selection. Anion exchange is an effective treatment for transphilic species, known for high carboxylic acid functionality, and consequently is recommended for carboxylic acid precursors. Amino acids have been linked to HAA formation and are important constituents of algal organic matter. Amino acids are predicted to be effectively removed by biotreatment and nanofiltration. Carbohydrates have been found to reach 50% of NOM in river waters. If the carbohydrates were to pose a barrier to successful DBP control, additional treatment stages such as nanofiltration are likely to be required to reduce their occurrence.

The nitrosamines are potent carcinogens which can be formed as by-products during water treatment. Much recent research activity has been focussed upon the formation, occurrence and control of N-nitrosodimethylamine (NDMA) in particular. In this study, seven secondary amines were oxidised by chlorine, ozone, and UV-irradiation, with and without post-chloramination, to quantify the effect on the formation of seven nitrosamines, including NDMA. While the yields of nitrosamines ranged from 0.01% for N-nitroso-di-n-butylamine (NDBA) to 2.01% for N-nitrosopyrrolidine (NPYR) under conditions of excess monochloramine at pH 7, yields from other oxidants were zero. Pre-oxidation with chlorine reduced nitrosamine formation by up to 83% compared with chloramination alone. This illustrates that in situations where secondary amines are key precursors, chlorine addition before ammonia during chloramination can be expected to limit nitrosamine formation. UV irradiation at 40 mJ cm−2 had little observed impact. Ozonation enhanced NDMA and N-nitrosomethylethylamine (NMEA) formation by subsequent chloramination to 7.48% and 10.15%, respectively.

Shortage of freshwater is a serious global problem, and expected to become even more urgent over the next decades. Many of the driest regions worldwide are close to the sea, but irrigation of fields with seawater–even if diluted–leads to the build-up of salt levels in the soil that are toxic to all common food crops (http://www.unwater.org). Current desalination technologies such as membrane-based reverse osmosis, are successfully used in large-scale desalination plants, however, they are expensive and energy inefficient [1]. Our multi-disciplinary team of biologists and engineers from 5 UK universities is working on an innovative desalination technology based on biological processes [2]. The “Biodesalination” strategy envisions the use of photosynthetic cyanobacteria modified with light-driven ion transport proteins to function as ion exchangers that selectively remove sodium chloride from seawater. This process would harness solar energy to provide a more cost effective and energetically sustainable desalination process.

The presence of nitrogenous disinfection by-products (N-DBPs), including nitrosamines, cyanogen halides, haloacetonitriles, haloacetamides and halonitromethanes, in drinking water is of concern due to their high genotoxicity and cytotoxicity compared with regulated DBPs. Occurrence of N-DBPs is likely to increase if water sources become impacted by wastewater and algae. Moreover, a shift from chlorination to chloramination, an option for water providers wanting to reduce regulated DBPs such as trihalomethanes (THMs) and haloacetic acids (HAAs), can also increase certain N-DBPs. This paper provides a critical review of the occurrence and control of N-DBPs. Data collated from surveys undertaken in the United States and Scotland were used to calculate that the sum of analysed halonitromethanes represented 3–4% of the mass of THMs on a median basis; with Pearson product moment correlation coefficients of 0.78 and 0.83 between formation of dihaloacetonitriles and that of THMs and HAAs respectively. The impact of water treatment processes on N-DBP formation is complex and variable. While coagulation and filtration are of moderate efficacy for the removal of N-DBP precursors, such as amino acids and amines, biofiltration, if used prior to disinfection, is particularly successful at removing cyanogen halide precursors. Oxidation before final disinfection can increase halonitromethane formation and decrease N-nitrosodimethylamine, and chloramination is likely to increase cyanogen halides and NDMA relative to chlorination.

Potentially the most effective means of controlling disinfection by-products (DBPs) is to remove precursors before disinfection. To understand relationships between physical properties, treatability and DBP formation, nine natural organic matter (NOM) surrogates were studied. Their DBP formation and removal by coagulation, MIEX® anion exchange resin and two nanofiltration membranes was measured. Whereas treatability of NOM surrogates was explained in terms of their physicochemical properties, the same was not true of DBP formation. Hence it was not possible to selectively remove compounds which generate high amounts of DBPs. Instead, precursor removal strategies based upon empirical DBP formation potential testing are more apt. Under conditions simulating full-scale performance, MIEX® did not offer improved performance over coagulation. A hydrophobic nanofiltration membrane proved successful for removing neutral, hydrophilic surrogates, and hence is also suitable for DBP precursors of this character.

Sleep-disordered breathing is defined as abnormal breathing patterns that disrupt sleep [1]. There are several types of sleep-disordered breathing patterns including hypopneas, apneas, and respiratory effortrelated arousals. Apnea is defined as a cessation of airflow for 10 or more seconds [2,3]. Partial obstructive events called hypopneas have historically been defined differently by different sleep disorders centers and sleep specialists. Because of a lack of uniformity in definitions, and partly because of difficulties in diagnosing and treating Medicare patients, the American Academy of Sleep Medicine has recently redefined hypopneas as abnormal respiratory events lasting at least 10 seconds, with at least a 30% reduction in airflow or thoracoabdominal movement with at least a 4% oxygen desaturation. The associated arousals historically associated with hypopneas have now been eliminated from the definition. This new definition is based on epidemiological data relating to sleep-related breathing disorders and cardiac disease [2]. The data relating to obstructive sleep apnea syndrome, and to both cardiovascular and cerebrovascular disease, is growing. Another abnormal breathing pattern is termed upper airway resistance syndrome. It is diagnosed in patients who present with daytime sleepiness caused by a narrowing or increased resistance of their upper airway when sleeping without diagnosable apneas or hypopneas. These patients generally have brief electroencephalography (EEG) arousals that may fragment sleep and cause the complaint of daytime sleepiness [4]. Common characteristics of patients who present for an apnea consultation include obesity, sleepiness, snoring, snorting, gasping, choking, and witnessed apneas at night. Hypertension, nocturia, and morning headaches may also be experienced. Patterns of apnea