Long-term dissolved organic carbon changes in Woronora drinking water system in Australia.

Assessing historical records of DOC concentrations (DOC) in drinking water sources is important for water utilities to understand long-term planning for infrastructure needs. This study investigates 15-20 years of historical data of the Woronora water supply catchment in Australia inclusive of the water filtration plant (WFP), the lake from where the water was drawn for WFP supply, and the two primary river inputs. The DOC at each site ranged from 0.

Microwave pyrolysis of polypropylene, and high-density polyethylene, and catalytic gasification of waste coffee pods to hydrogen-rich gas.

Plastic waste poses a critical environmental challenge for the world. The proliferation of waste plastic coffee pods exacerbates this issue. Traditional disposal methods such as incineration and landfills are environmentally unfriendly, necessitating the exploration of alternative management strategies.

The influence of recent bushfires on water quality and the operation of water purification systems in regional NSW.

Over the past decade, escalating extreme weather events have significantly affected New South Wales (NSW), Australia, with unprecedented droughts and intense fires. Yet, the impact on water quality and purification processes remains insufficiently studied. This research focuses on the immediate changes in NSW's environmental water quality and issues in water purification unit operations following the 2019 bushfires.

Heterotrophic bacteria isolated from a chloraminated system accelerate chloramine decay.

This work comprehensively demonstrates the ability of heterotrophic bacteria, isolated from a chloraminated system, to decay chloramine. This study non-selectively isolated 62 cultures of heterotrophic bacteria from a water sample (0.002 mg-N/L nitrite and 1.

Effective chloramine management without "burn" in biofilm affected nitrifying tanks using a low dose of copper.

This paper highlights the potential to effectively inhibit nitrification and restore chloramine levels using a low copper concentration in a biofilm-affected (surface-to-volume ratio 16 m) continuous-flow laboratory-scale chloraminated system. High nitrite and low chloramine containing tanks are always recovered with chlorine "burn" by water utilities. The "burn" is not only costly and operationally complex, but also compromises the water quality, public health, and customer relations.

Model for halo-acetic acids formation in bulk water of water supply systems.

With increased understanding of the differences in toxicity between species of haloacetic acids (HAAs) and the possibility of more stringent regulations, the ability to predict individual HAA species formation is important. Nine different haloacetic acids are regulated and their total concentration is referred to as HAA9. A mathematical model to predict concentrations of HAA species was proposed and tested using independent data sets.

Multivariate experimental design provides insights for the optimisation of rechloramination conditions and water age to control disinfectant decay and disinfection by-product formation in treated drinking water.

The stability of drinking water disinfectant residuals is known to be influenced by multiple variables. To evaluate the effects of various influencing variables on disinfectant stability, a multivariate analysis of chloramine decay and associated disinfection by-products (DBPs) formation was investigated in a series of bench-scale experiments. Of nine water quality variables previously identified, monochloramine dose, pH, and bromide concentration were selected as key water quality variables based on previous investigations and modelling.

Factors controlling the effectiveness of rechlor(am)ination to recover chloramine from nitrification.

The two most commonly adopted strategies, rechlorination (addition of chlorine) and rechloramination (addition of chlorine and ammonia), to recover and stabilise chloramine from nitrification were comprehensively evaluated in laboratory- and full-scale systems. Laboratory-scale batch experiments were conducted in a nitrifying sample (~0.05 mg-N/L).

Comparative characterization of microbial communities that inhabit PFAS-rich contaminated sites: A case-control study.

The historic usage and discharge of per- and polyfluoroalkyl substances (PFAS) containing chemicals have produced many contaminated sites and PFAS contamination has become a global concern due to their persistence, widespread distribution, and potential adverse impacts for human and environmental health. However, there have been limited investigations on the specific behavior of bacterial communities in PFAS contaminated soils. In this study, a quantitative PCR assay and Illumina MiSeq sequencing were used to investigate the variations of bacterial communities in a regional Australian airport contaminated with PFAS.

Effect of backwashing biologically activated carbon on coagulability of organics in surface water.

This study shows if biologically activated carbon (BAC) is backwashed at the correct frequency, a number of benefits can be derived in addition to aiding the subsequent coagulation process. Previous studies have shown that the BAC improves the removal of dissolved organic carbon (DOC) by subsequent coagulation by decreasing non-coagulable dissolved organic carbon (NC-DOC). However, the actual mechanism of such observation or optimising strategies of NC-DOC removal is unknown.

The role of pH on sewer corrosion processes and control methods: A review.

The production and emission of hydrogen sulfide (HS) in sewer systems is associated with the corrosion of sewer structures and harmful odour. Numerous studies have been conducted to find the best solution to overcome this issue. The pH plays a critical role not only on microbial and chemical processes that are responsible for all processes of corrosion but also on the efficiency of several control methods.

A multivariate Bayesian network analysis of water quality factors influencing trihalomethanes formation in drinking water distribution systems.

Controlling disinfection by-products formation while ensuring effective drinking water disinfection is important for protecting public health. However, understanding and predicting disinfection by-product formation under a variety of conditions in drinking water distribution systems remains challenging as disinfection by-product formation is a multifactorial phenomenon. This study aimed to assess the application of Bayesian Network models to predict the concentration of trihalomethanes, the dominant halogenated disinfection by-product class, using various water quality parameters.

An assessment of the persistence of putative pathogenic bacteria in chloraminated water distribution systems.

This study investigated how a chloramine loss and nitrifying conditions influenced putative pathogenic bacterial diversity in bulk water and biofilm of a laboratory- and a full-scale chloraminated water distribution systems. Fifty-four reference databases containing full-length 16S rRNA gene sequences obtained from the National Centre for Biotechnology Information database were prepared to represent fifty-four pathogenic bacterial species listed in the World Health Organisation and Australian Drinking Water Quality Guidelines. When 16S rRNA gene sequences of all samples were screened against the fifty-four reference pathogenic databases, a total of thirty-one putative pathogenic bacteria were detected in both laboratory- and full-scale systems where total chlorine residuals ranged between 0.

Simplified chemical chloramine decay model for water distribution systems.

This paper, presents a simplified model for predicting chemical chloramine loss in ultrapure water as a function of various measurable parameters, which otherwise requires the simulation of a complex mechanistic model involving the implementation of a number of ordinary differential equations (ODE), using specialised software. The complexity of the mechanistic model is evidenced by its lack of use outside chemical reaction modelling academics. We developed a simplified model as a single-line equation with eight fixed coefficients to predict the first-order decay coefficient.

Trihalomethane species model for drinking water supply systems.

Despite the existence of significant knowedge on complex mechanisms of THM formation, a simple kinetic model to predict THM species concentration is not available, hindering application of knowlwdge for regulatory, monitoring and operational control. The parallel second order reaction (2R) model containing fast and slow reactants has been well established to describe the chlorine decay kinetics under distribution conditions. The proposed THM species model expands the 2R model by systematically incorporating the initial unproductive (not forming THM) chlorine consumption and assuming each THM species is formed at a fixed yield (µg-THM species/mg- productive chlorine consumption).

Hydrogen sulphide control in sewers by catalysing the reaction with oxygen.

This work for the first time shows possible advantage of using ferrous as a catalyst to selectively oxidise hydrogen sulphide in sewer water where biological activity is present. Ferrous catalysed the oxidation reaction in all conditions, but the oxygen requirement for the chemical oxidation of sulphide varied depending on the initial conditions (pH, concentrations of sulphide and oxygen). For initial concentrations of O and S exceeding 2 mg/L, and a pH between 7.

The chloramine stress induces the production of chloramine decaying proteins by microbes in biomass (biofilm).

In this paper, for the first time, we show in chloraminated systems, the chloramine decaying proteins (CDP) play an important role in bulk water and biomass (biofilm) in resisting disinfectant. Extracellular polymeric substances in biofilm/biomass are known to protect microbes from disinfectants and toxic materials, but the exact mechanism(s) is/are not known. Starting with the seed from a nitrifying chloraminated reactor, two 5 L reactors were fed intermittently with either chloramine or ammonia containing nutrient solution.

Disinfectant residual stability leading to disinfectant decay and by-product formation in drinking water distribution systems: A systematic review.

Secondary disinfectants, such as chlorine and chloramine, have been widely applied to minimise microbial risks in drinking water during distribution. Key challenges have included the maintenance of stable concentrations of disinfectant residuals and the control of disinfection by-products that may form as a consequence of residual decay processes. Many factors may influence disinfectant residual stability and the consequential formation of by-products.

Effects of feed water NOM variation on chloramine demand from chloramine-decaying soluble microbial products during rechloramination.

Earlier, we reported on soluble microbial products-mediated chloramine decay in nitrifying waters. However, we neither separated the agent(s) nor identified the factors that enhanced the production of chloramine-decaying soluble microbial products (cSMPs). Experiments were conducted by feeding reactor sets (each consisting of five reactors connected in series) with treated water (3-8 mg-DOC.

New model of chlorine-wall reaction for simulating chlorine concentration in drinking water distribution systems.

Accurate modelling of chlorine concentrations throughout a drinking water system needs sound mathematical descriptions of decay mechanisms in bulk water and at pipe walls. Wall-reaction rates along pipelines in three different systems were calculated from differences between field chlorine profiles and accurately modelled bulk decay. Lined pipes with sufficiently large diameters (>500 mm) and higher chlorine concentrations (>0.

A review: Potential and challenges of biologically activated carbon to remove natural organic matter in drinking water purification process.

The use of biologically activated carbon (BAC) in drinking water purification is reviewed. In the past BAC is seen mostly as a polishing treatment. However, BAC has the potential to provide solution to recent challenges faced by water utilities arising from change in natural organic matter (NOM) composition in drinking water sources - increased NOM concentration with a larger fraction of hydrophilic compounds and ever increasing trace level organic pollutants.

Modelling combined effect of chloramine and copper on ammonia-oxidizing microbial activity using a biostability approach.

Continuous and batch laboratory experiments were used to evaluate the combined effects of copper and chloramine on ammonia oxidizing microbes present in otherwise high nitrifying water samples. The experimental data were analyzed using a biostability concept and quantified with the biostable residual concentratrion (BRC) of monochloramine, or the concentration that prevents the onset of nitrification. In the batch experiments, copper dosing ≥0.

Combined BAC and MIEX pre-treatment of secondary wastewater effluent to reduce fouling of nanofiltration membranes.

Biological activated carbon (BAC) and magnetic ion exchange resin (MIEX) were used to pre-treat secondary wastewater effluent (SWWE) and assessed for their capacity to reduce fouling of a nanofiltration membrane. BAC pre-treated water facilitated a lower but a steady flux while MIEX treated water resulted in a higher but a rapidly declining flux. Their combined use increased average flux from 58 to 89%.

Effectiveness of breakpoint chlorination to reduce accelerated chemical chloramine decay in severely nitrified bulk waters.

Rectifying the accelerated chloramine decay after the onset of nitrification is a major challenge for water utilities that employ chloramine as a disinfectant. Recently, the evidence of soluble microbial products (SMPs) accelerating chloramine decay beyond traditionally known means was reported. After the onset of nitrification, with an intention to inactivate nitrifying bacteria and thus maintaining disinfectant residuals, breakpoint chlorination followed by re-chloramination is usually practiced by water utilities.