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Adhikari and Neupane

However, the hardness was decreased with increasing or fulvic acids, and proteins. It is considered that the
MO concentration (Figure 5D), which could be attributed small-sized charged particles in MO seeds interact with
to adsorption and inter-particle bridging. After water suspended particles and bond with oppositely charged
29
treatment, lightweight solids/flocs were observed, which metal ions, forming coagulants and removing metal
may be precipitation of soluble carbonate and bicarbonate ions by filtration. 18,32-34
ions, causing a reduction of hardness. 9
Heavy metals are environmental pollutants of 3.3.2. Bacteriological remediation of river water
particular concern due to their toxicity. The non- The river is unsafe for drinking and other domestic uses
18
biodegradable and persistent properties of heavy because it is highly contaminated with microorganisms.
metals pose serious ecotoxicological problems, with The microbial load on polluted river water was very
mutagenic, genotoxic, teratogenic, and carcinogenic high and beyond the limit of measurement. After river
effects on human health. The efficiency of heavy metal water treatment, the microbial concentration drastically
removal using MO was determined by measuring iron decreased with increasing MO concentration, (50 –
and chromium concentrations in the river water samples 200 mg/L) (Table 2). It was observed that 100 mg/L
(B-1 and B-2) treated with different MO concentrations. MO decreased the microbial load by up to 78.18%,
The concentrations of iron in both samples were more even for heavily polluted river water samples (B-2). The
than 4 times higher than the WHO standard. After microorganisms identified from SPC were Escherichia
treatment, the iron concentration was reduced to 0.62, coli and Klebsiella species. There was a reduction in
0.56, and 0.54 ppm at 50, 100, and 200 mg/L of MO, the microbial load of both species. After treatment, the
respectively, for the B-1 water samples. Similarly, in the bacterial colonies were reduced to 4.8 × 10 from an
7
B-2 water samples, the iron concentration was reduced infinite number (i.e., TMTC). With proper mixing of MO
from 1.53 ppm to 0.74, 0.68, and 0.62 ppm at 50, 100, and contaminated water, the particles were enlarged, and
and 200 mg/L, respectively (Figure 5E). It was reported flocs were formed that settled at the bottom of the vessel.
that MO seeds consist of glucosinolates and phenolics The results indicate that MO seeds have good coagulation
(flavonoids, anthocyanins, proanthocyanidins, and properties, which are useful to treat heavily polluted
cinnamates). The central carbon atoms of each river water. Although there was a drastic decrease in
32
glucosinolate are bonded to the thio-glucose group MPN counts in treated water, the count was still above
through a sulfur atom, forming a sulfate ketoxime, and the limits of WHO standards. Hence, further treatment is
are also bonded to a sulfate group via a nitrogen atom. suggested for the complete removal of microbiological
These functional groups that contain sulfur and nitrogen pollutants with higher doses of MO. It was reported
are responsible for good metal reduction in river water. 15 that the active compound 4-alpha rhamnosyloxy-
The concentration of chromium in the river water benzyl isothiocyanate, known as glucosidal mustard oil,
samples was more than 5 times higher than the WHO coagulates solid matter, including suspended bacteria,
standard. After treatment with MO, the concentration of and facilitates their easy removal. 9
chromium was decreased from 0.27 ppm to 0.09, 0.05,
and 0.04 ppm, with increasing coagulant concentrations 3.3.3. Comparison of efficacy of MO and citric-acid-
of MO of 50, 100, and 200 mg/L, respectively, for B-1 treated MO seed extracts on water treatment
river water samples (Figure 5F). Similarly, in B-2 water The bioremediation efficiency of MO powder was
samples, the concentration of chromium was reduced enhanced by modifying the surface morphology with
from 0.39 ppm to 0.12, 0.08, and 0.07 ppm with citric acid. Chemical treatment increased the surface
increasing coagulant concentrations of 50, 100, and area, thereby improving its adsorption capacity. The
200 mg/L, respectively (Figure 5F). It was observed removal/reduction efficiencies of MO and CAMO were
that the concentrations of chromium in river samples compared by treating polluted river water samples (B-1
were drastically reduced to the acceptable standard and B-2) using 100 mg/L extracts. The comparative
value using MO. This could be due to the presence of results of bio-remediation of turbidity, total hardness,
amphoteric proteins in MO seeds that bind to oppositely and heavy metal (Fe and Cr) concentrations of both
charged metal ions, leading to metal precipitation. Since river water samples are displayed in Figure 6A and B.
metals are present in dissolved or particulate forms, The treatment efficiency of CAMO was higher than
they can exist as free hydrated ions or as complex ions that of MO. The turbidity reduction efficiency of MO
chelated with inorganic ligands, such as chlorides and was 87.57% and 87.12% for B-1 and B-2 samples,
carbonates, or organic ligands, such as amines, humic respectively. The efficiency was higher at 93.78% and

Volume 22 Issue 1 (2025) 48 doi: 10.36922/ajwep.8434