Effectiveness of tertiary treatment processes in removing different classes of emerging contaminants from domestic wastewater

In this work,38 different organic emerging contaminants(ECs),belonging to various chemical classes such as pharmaceuticals(PhCs),endocrine-disrupting chemicals(EDCs),benzotriazoles(BTRs),benzothiazoles(BTHs),and perfluorinated compounds(PFCs),were initially identified and quantified in the biologically treated wastewater collected from Athens’(Greece)Sewage Treatment Plant(STP).Processes already used in existing STPs such as microfiltration(MF),nanofiltration(NF),ultrafiltration(UF),UV radiation,and powdered activated carbon(PAC)were assessed for ECs’removal,under the conditions that represent their actual application for disinfection or advanced wastewater treatment.The results indicated that MF removed only one out of the 38 ECs and hence it was selected as pretreatment step for the other processes.UV radiation in the studied conditions showed low to moderate removal for 5 out of the 38 ECs.NF showed better results than UF due to the smaller pore sizes of the filtration system.However,this enhancement was observed mainly for 8 compounds originating from the classes of PhCs and PFCs,while the removal of EDCs was not statistically significant.Among the various studied technologies,PAC stands out due to its capability to sufficiently remove most ECs.In particular,removal rates higher than 70%were observed for 9 compounds,22 were partially removed,while 7 demonstrated low removal rates.Based on our screening experiments,future research should focus on scaling-up PAC in actual conditions,combining PAC with other processes,and conduct a complete economic and environmental assessment of the treatment.

Effectiveness of Centralized Wastewater Treatment Plant in Removing Emerging Contaminants: A Case Study at Kuching, Malaysia

Before the construction of the Kuching Centralized Wastewater Treatment System Package 1 (KCWTSP1), partially treated blackwater and greywater were discharged directly into natural waterways. The accumulated wastewater had polluted Sarawak river, which is regulated and cannot discharge freely into the South China Sea. The polluted Sarawak river has endangered human health, river water quality, and aquatic ecosystems. Hence, the KCWTSP1 commissioned in 2015 serves the purpose of removing pollutants from wastewater before it is discharged into natural waterways. However, the effectiveness of KCWTPP1 is unknown. This paper is aimed to discuss and review the effectiveness of KCWTPP1 in treating wastewater since its inception in 2015. From 2017 to 2020, KCWTPP1 has treated an average of 4,200,000 m3 of wastewater per year. Generally, most of the discharge effluent met Environmental Quality Act (1974) Standard A criteria, except for the oil and grease parameter. Initially, the plant could not treat suspended solids and total phosphorus, but this was greatly improved in subsequent years. Therefore, some improvements are required to treat oil and grease parameters effectively and efficiently to ensure that only Standard A effluent is discharged into the Sarawak River in the future.

Significant increase of assimilable organic carbon(AOC)levels in MBR effluents followed by coagulation,ozonation and combined treatments:Implications for biostability control of reclaimed water

As water reuse development has increased,biological stability issues associated with reclaimed water have gained attention.This study evaluated assimilable organic carbon(AOC)in effluents from a full-scale membrane biological reactor(MBR)plant and found that they were generally stable over one year(125-216µg/L),with slight increases in warmer seasons.After additional tertiary treatments,the largest increases in absolute and specific AOCs were detected during ozonation,followed by coagulation-ozonation and coagulation.Moreover,UV254 absorbance is known to be an effective surrogate to predict the AOC changes during ozonation.Applying coagulation prior to ozonation of MBR effluents for removal of large molecules was found to reduce the AOC formation compared with ozonation treatment alone.Finally,the results revealed that attention should be paid to seasonal variations in influent and organic fraction changes during treatment to enable sustainable water reuse.