The role of coagulation on the fate of PFAS, brominated flame retardants and other trace contaminants in tertiary wastewater treatment for phosphorus control.

Coagulant dosing to achieve low phosphorus concentrations in wastewater effluents may favour the removal of trace organics such as pharmaceuticals, plasticisers and flame retardants. Nevertheless, the behaviour of trace organics in coagulation processes is currently poorly understood because of the complex interactions between these compounds, the coagulants and dissolved organic matter (DOM). This study assessed the coagulation removal from synthetic secondary effluent of twenty-four compounds including ten PFAS and four brominated flame retardants. Testing involved two coagulants (alum, ferric chloride) and five DOM surrogates (resorcinol, benzoic acid, citric acid, tannic acid, humic acid); DOM surrogates had assorted molecular weights, structures, charges, and hydrophobicity. With coagulant doses of 14 mg Fe/L and 4 mg Al/L, ten trace organics were removed by >30 % in the presence of at least one DOM surrogate. Humic acid effected the highest removals owing to complexation of trace organics and subsequent co-removal by adsorption or sweep floc. For instance, removal extents for three brominated diphenyl ethers were 60 to 75 % with Al and 50 to 88 % with Fe (initial concentration 0.4 to 0.8 ng/L); PFTDA, a long-chain PFAS, was removed by 87 and 91 % with Fe in the presence of tannic or humic acid, respectively (initial concentration 0.03 µg/L). The varying coagulation performance of different treatment works in terms of trace substance removal can be explained because of the site-specific DOM characteristics. Addition of humic acids as complexing agents has the potential to improve the removal of hydrophobic trace substances, including some long-chain PFAS and brominated flame retardants.

Citric acid application for denitrification process support in biofilm reactor.

The study demonstrated that citric acid, as an organic carbon source, can improve denitrification in Anaerobic Sequencing Batch Biofilm Reactor (AnSBBR). The consumption rate of the organic substrate and the denitrification rate were lower during the period of the reactor's acclimatization (cycles 1-60; 71.5 mgCOD L-1 h-1 and 17.81 mgN L-1 h-1, respectively) than under the steady state conditions (cycles 61-180; 143.8 mgCOD L-1 h-1 and 24.38 mgN L-1 h-1). The biomass yield coefficient reached 0.04 ± 0.02 mgTSS· mgCODre-1 (0.22 ± 0.09 mgTSS mgNre-1). Observations revealed the diversified microbiological ecology of the denitrifying bacteria. Citric acid was used mainly by bacteria representing the Trichoccocus genus, which represented above 40% of the sample during the first phase of the process (cycles 1-60). In the second phase (cycles 61-180) the microorganisms the genera that consumed the acetate and formate, as the result of citric acid decomposition were Propionibacterium (5.74%), Agrobacterium (5.23%), Flavobacterium (1.32%), Sphaerotilus (1.35%), Erysipelothrix (1.08%).

Effect of the C:N:P ratio on the denitrifying dephosphatation in a sequencing batch biofilm reactor (SBBR).

A series of investigations were conducted using sequencing batch biofilm reactor (SBBR) to explore the influence of C:N:P ratio on biological dephosphatation including the denitrifying dephosphatation and the denitrification process. Biomass in the reactor occurred mainly in the form of a biofilm attached to completely submerged disks. Acetic acid was used as the source of organic carbon. C:N:P ratios have had a significant effect on the profiles of phosphate release and phosphate uptake and nitrogen removal. The highest rates of phosphate release and phosphate uptake were recorded at the C:N:P ratio of 140:70:7. The C:N ratio of 2.5:1 ensured complete denitrification. The highest rate of denitrification was achieved at the C:N:P ratio of 140:35:7. The increase of nitrogen load caused an increase in phosphates removal until a ratio C:N:P of 140:140:7. Bacteria of the biofilm exposed to alternate conditions of mixing and aeration exhibited enhanced intracellular accumulation of polyphosphates. Also, the structure of the biofilm encouraged anaerobic-aerobic as well as anoxic-anaerobic and absolutely anaerobic conditions in a SBBR. These heterogeneous conditions in the presence of nitrates may be a significant factor determining the promotion of denitrifying polyphosphate accumulating organism (DNPAO) development.

Recycling potential of air pollution control residue from sewage sludge thermal treatment as artificial lightweight aggregates.

Thermal treatment of sewage sludge produces fly ash, also known as the air pollution control residue (APCR), which may be recycled as a component of artificial lightweight aggregates (ALWA). Properties of APCR are typical: high content of Ca, Mg, P2O5, as well as potential to induce alkaline reactions. These properties indicate that ALWA prepared with a high content of APCR may remove heavy metals, phosphorus, and ammonium nitrogen from wastewater with high efficiency. The aim of this preliminary study was to determine the optimal composition of ALWA for potential use as a filter media in wastewater treatment systems. Five kinds of ALWA were produced, with different proportions of ash (shown as percentages in subscripts) in mixture with bentonite: ALWA0 (reference), ALWA12.5, ALWA25, ALWA50, and ALWA100. The following parameters of ALWA were determined: density, bulk density, compressive strength, hydraulic conductivity, and removal efficiency of ions Zn(2+), NH4 (+), and PO4 (3-). Tests showed that ALWA had good mechanical and hydraulic properties, and might be used in wastewater filtering systems. Phosphates and zinc ions were removed with high efficiency (80-96%) by ALWA25-100 in static (batch) conditions. The efficiency of ammonium nitrogen removal was low, <18%. Artificial wastewater treatment performance in dynamic conditions (through-flow), showed increasing removal efficiency of Zn(2+), PO4 (3-) with a decrease in flow rate.

Effect of fermented wastewaters from butter production on phosphates removal in a sequencing batch reactor.

This study determined the potential for fermented wastewaters from butter production plant to act as a carbon source to facilitate phosphates removal. Synthetic dairy wastewaters were treated using SBR, with doses of fermented wastewaters. An increase in the fermented wastewater doses were found to improve the effluent quality in respect of phosphates and nitrates. The lowest concentrations of phosphate and nitrates, respectively 0.10 ± 0.04 mg PO(4)-PL(-1) and 1.03 ± 0.22 mg NO(3)-NL(-1), were noted in the effluent from the reactor fed with fermented wastewaters in a dose of 0.25 L d(-1) per 0.45 L d(-1) of wastewaters fed to the reactor. In the case of the two highest doses, an increase in effluent COD was stated. The higher effectiveness resulted from the fact that the introduction of fermented wastewaters caused an increase in the easily-available carbon compounds content and the predominance of acetic acid amongst VFAs available to dephosphatating and denitrifying bacteria.

Equivalent immunogenicity of the highly attenuated poxvirus-based ALVAC-SIV and NYVAC-SIV vaccine candidates in SIVmac251-infected macaques.

Therapeutic immunization of HIV-1-infected individuals may induce and/or enhance HIV-1-specific immune responses and decrease the dependency on antiretroviral drug treatment. However, repeated immunizations with live-recombinant vectors may induce vector-specific immune responses that interfere with the elicitation of vigorous immune responses to the desired antigen. Therefore, the use of mixed-modality vaccinations may be necessary to induce sustained virus-specific immune responses in HIV-1-infected individuals treated with antiretroviral therapy (ART). Thus, the relative immunogenicity of various vaccine modalities needs to be assessed. Here we compared the immunogenicity of two vaccine candidates, the canarypox-based ALVAC-SIV-gag-pol-env (ALVAC-SIV-gpe) and the vaccinia-based NYVAC-SIV-gag-pol-env (NYVAC-SIV-gpe), in rhesus macaques infected with SIVmac251 and treated with ART by 2 weeks postinfection. Both ALVAC-SIV-gpe and NYVAC-SIV-gpe vaccine candidates induced and/or enhanced a virus-specific CD8+ T cell response to a similar extent, as demonstrated by tetramer staining of Gag-specific CD8+ T cells. Similarly, both vaccines elicited comparable lymphoproliferative responses (LPRs) to the SIV p27 Gag and gp120 Env proteins. Thus, both these vaccine modalities alone or in combination may be suitable candidate vaccines for immune therapy of HIV-1-infected individuals.