338
R. Kumar et al.
acquire wastewater from hospitals and municipal sewages where antibiotics are predominantly utilized, which leads to the presence of considerably large amounts of
ARGs (Rodriguez-Mozaz et al. 2015). Second, prolonged selective pressures from
the antibiotic remnants at sub-inhibitory concentrations in these wastewater on the
microbes in the activated sludge naturally favor the occurrence of ARGs (Kim
et al. 2014). Another cost-effective design to treat wastewater is constructed wetlands (CWs) which include several steps of natural procedures employing live flora,
soil/sludge/sediment and microbes that can reduce the pollutants (Vymazal 2011).
In contrast to techniques like activated sludge, the benefits of CWs are many including cheaper construction, less energy intensive, low maintenance, minimal labor and
high treatment efficiency. These benefits allow the CWs to be more sustainable and a
better substitute in developing countries with majority of rural areas (Fernandes et al.
2015; Huang et al. 2015a, b). Guo et al. (2015) studied the efficiency of activated
sludge, Fenton process activated sludge and individual Fenton process. When the
concentration of amoxicillin was less than 350 mg/L, 69.04–88.79% of the antibiotic was removed. Meng et al. (2017) investigated the continual effect of cefalexin
(CFX) on the microbial community and efficiency of an expanded granular sludge
bed (EGSB) treatment system. The addition of CFX to the reactor had affected the
COD removal efficiency and reactor tried to recover after 122 d of operation. Yu
et al. (2019) studied the effect of ampicillin on the reactor efficiency, rate of nutrient
removal, microbial community structure, evaluation of extracellular polymeric substances (EPS) and enhanced enzymatic activity in the activated sludge of a sequencing
batch reactor (SBR) system. Ampicillin was found to inhibit the sludge activity and
enzyme activity at a concentration of 20 and 30 mg/L. The mode of action of antibiotics is precise and basically inhibits the cellular machinery function which includes
inhibition in cell wall synthesis, inhibitors of bacterial beta lactamases, inhibitor
for protein synthesis, inhibits transcription and translation and inhibition of DNA
replication (Gothwal and Shashidhar 2015).
Laboratory-based research indicated the possible risks of ARG distribution when
vertical up-flow constructed wetlands (VUF-CWs) are operated for the removal of
antibiotic containing wastewaters. The results showed high removal effectiveness of
>98% for both tetracycline (TC) and sulfamethoxazole (SMX) (Song et al. 2018).
Diverse mesocosm horizontal subsurface-flow CWs containing various design frameworks with Cyperus alternifolius L. plants were assessed by Chen et al. (2016).
Many researchers also used zeolite, oyster shells, ceramic, medical stone, etc., in
order and optimized the best combination for treating wastewater. In the attempt, ~
seven antibiotics, viz., lincomycin, erythromycin-H 2 O, ofloxacin monensin, sulfamerazine, novobiocin and sulfamethazine, and 18 genes (fexA, floR, fexB, sul1, sul2
and sul3, ermC, ermB, tetG, tetO, tetM, tetX, qnrB, qnrS, qnrD, cmlA, int1 and int2)
were found significant in the domestic wastewaters. In these CWs, the obliterations
(%) of the antibiotics were found to be in between from 17.9 to 98.5%, whereas that
for the ARGs ranged between 50.0 and 85.8%.
In WWTPs with submerged aerated filters and dribbling kind of filters, the overall
plethora of bacteria resistant to tetracycline declined by N2 log units CFU/100 mL as
reported by Fry and Day (1990) and Galvin et al. (2010) and b1 log units CFU/100 mL
R. Kumar et al.
acquire wastewater from hospitals and municipal sewages where antibiotics are predominantly utilized, which leads to the presence of considerably large amounts of
ARGs (Rodriguez-Mozaz et al. 2015). Second, prolonged selective pressures from
the antibiotic remnants at sub-inhibitory concentrations in these wastewater on the
microbes in the activated sludge naturally favor the occurrence of ARGs (Kim
et al. 2014). Another cost-effective design to treat wastewater is constructed wetlands (CWs) which include several steps of natural procedures employing live flora,
soil/sludge/sediment and microbes that can reduce the pollutants (Vymazal 2011).
In contrast to techniques like activated sludge, the benefits of CWs are many including cheaper construction, less energy intensive, low maintenance, minimal labor and
high treatment efficiency. These benefits allow the CWs to be more sustainable and a
better substitute in developing countries with majority of rural areas (Fernandes et al.
2015; Huang et al. 2015a, b). Guo et al. (2015) studied the efficiency of activated
sludge, Fenton process activated sludge and individual Fenton process. When the
concentration of amoxicillin was less than 350 mg/L, 69.04–88.79% of the antibiotic was removed. Meng et al. (2017) investigated the continual effect of cefalexin
(CFX) on the microbial community and efficiency of an expanded granular sludge
bed (EGSB) treatment system. The addition of CFX to the reactor had affected the
COD removal efficiency and reactor tried to recover after 122 d of operation. Yu
et al. (2019) studied the effect of ampicillin on the reactor efficiency, rate of nutrient
removal, microbial community structure, evaluation of extracellular polymeric substances (EPS) and enhanced enzymatic activity in the activated sludge of a sequencing
batch reactor (SBR) system. Ampicillin was found to inhibit the sludge activity and
enzyme activity at a concentration of 20 and 30 mg/L. The mode of action of antibiotics is precise and basically inhibits the cellular machinery function which includes
inhibition in cell wall synthesis, inhibitors of bacterial beta lactamases, inhibitor
for protein synthesis, inhibits transcription and translation and inhibition of DNA
replication (Gothwal and Shashidhar 2015).
Laboratory-based research indicated the possible risks of ARG distribution when
vertical up-flow constructed wetlands (VUF-CWs) are operated for the removal of
antibiotic containing wastewaters. The results showed high removal effectiveness of
>98% for both tetracycline (TC) and sulfamethoxazole (SMX) (Song et al. 2018).
Diverse mesocosm horizontal subsurface-flow CWs containing various design frameworks with Cyperus alternifolius L. plants were assessed by Chen et al. (2016).
Many researchers also used zeolite, oyster shells, ceramic, medical stone, etc., in
order and optimized the best combination for treating wastewater. In the attempt, ~
seven antibiotics, viz., lincomycin, erythromycin-H 2 O, ofloxacin monensin, sulfamerazine, novobiocin and sulfamethazine, and 18 genes (fexA, floR, fexB, sul1, sul2
and sul3, ermC, ermB, tetG, tetO, tetM, tetX, qnrB, qnrS, qnrD, cmlA, int1 and int2)
were found significant in the domestic wastewaters. In these CWs, the obliterations
(%) of the antibiotics were found to be in between from 17.9 to 98.5%, whereas that
for the ARGs ranged between 50.0 and 85.8%.
In WWTPs with submerged aerated filters and dribbling kind of filters, the overall
plethora of bacteria resistant to tetracycline declined by N2 log units CFU/100 mL as
reported by Fry and Day (1990) and Galvin et al. (2010) and b1 log units CFU/100 mL