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.

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).

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.

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.

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.

Phosphorous removal from aqueous solution can be enhanced through the calcination of lime sludge.

Water treatment plants generate an enormous amount of the sludge which is normally treated as waste. In the recent past, many investigations have been focused on developing an economical adsorbent using water treatment sludge to remove phosphorous (P) from aqueous solutions. However, the great extents of the studies have been limited in the use of alum- and iron-based sludges.

Surfactant-enhanced remediation of polycyclic aromatic hydrocarbons: A review.

Polycyclic aromatic hydrocarbons (PAHs) are toxic, mutagenic and carcinogenic organic compounds that are widely present in the environment. The bioremediation of PAHs is an economical and environmentally friendly remediation technique, but it is limited because PAHs have low water solubility and fewer bioavailable properties. The solubility and bioavailability of PAHs can be increased by using surfactants to reduce surface tension and interfacial tension; this method is called surfactant-enhanced remediation (SER).

Comparative study of ground water treatment plants sludges to remove phosphorous from wastewater.

Alum- and iron-based sludge obtained from water treatment plant produced during a unit treatment process (coagulation and flocculation) have been widely tested as a low-cost adsorbent to remove phosphorous (P) from wastewater. However, the effectiveness of iron-based sludge generated from the oxidation of iron which naturally occurs in the ground water has not been investigated. Moreover, influences of dominant metals ions comprised in the treatment plants sludges on P adsorption capacity and rate from wastewater are not yet known.

Polycyclic aromatic hydrocarbons (PAHs) removal by sorption: A review.

Polycyclic aromatic hydrocarbons (PAHs) are organic micro pollutants which are persistent compounds in the environment due to their hydrophobic nature. Concerns over their adverse effects in human health and environment have resulted in extensive studies on various types of PAHs removal methods. Sorption is one of the widely used methods as PAHs possess a great sorptive ability into the solid media and their low aqueous solubility property.

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.

Microbial community changes with decaying chloramine residuals in a lab-scale system.

When chloramine is used as a disinfectant, managing an acceptable "residual" throughout the water distribution systems particularly once nitrification has set in is challenging. Managing chloramine decay prior to the onset of nitrification through effective control strategies is important and to-date the strategies developed around nitrification has been ineffective. This study aimed at developing a more holistic knowledge on how decaying chloramine and nitrification metabolites impact microbial communities in chloraminated systems.

Evidence of soluble microbial products accelerating chloramine decay in nitrifying bulk water samples.

The discovery of a microbially derived soluble product that accelerates chloramine decay is described. Nitrifying bacteria are believed to be wholly responsible for rapid chloramine loss in drinking water systems. However, a recent investigation showed that an unidentified soluble agent significantly accelerated chloramine decay.

Investigation on laboratory and pilot-scale airlift sulfide oxidation reactor under varying sulfide loading rate.

Airlift bioreactor was established for recovering sulfur from synthetic sulfide wastewater under controlled dissolved oxygen condition. The maximum recovered sulfur was 14.49 g/day when sulfide loading rate, dissolved oxygen (DO) and pH values were 2.