Integrated application of macrophytes and zooplankton for wastewater treatment

Abstract

The increasing amount of sewage has become a serious concern globally, demanding sustainable solutions. The constructed wetland system (CWS) can be installed at the wastewater discharge site and properly screened bio-purifiers can be used for efficient wastewater treatment. Filter-feeding zooplankton have the potential to graze on bacteria and reduce biological oxygen demand. However, higher suspended particles choke the zooplankton filtering appendages. An integrated application of zooplankton and macrophytes can solve the problems by reducing contaminants and providing the surface area for zooplankton to take refuge. Using three different approaches: (a) screening of natural bio-purifiers through time series study, (b) assessment of sewage treatment potential of screened bio-purifiers in the CWS and, (c) evaluation of the growth potential of screened bio-purifiers in untreated wastewater, this study explored the combined use of macrophyte and zooplankton in the CWS. The 3-year time series study in the vicinity of the wastewater discharge area recorded the zooplankton, Brachionus angularis and Moina macrocopa as highly indicative zooplankton. The top two highly indicative macrophytes are Typha and Phragmites. Under laboratory conditions, the population growth rates of B. angularis and M. macrocopa were significantly higher in wastewater without any external nutrient source than those in control with algae as a food source. The integrated application of zooplankton (B. angularis and M. macrocopa) macrophytes (Typha and Phragmites) in CWS yielded upto 56% reduction in the total bacterial count and upto 92% reduction in BOD along with substantial increase in the DO level. The present results strongly suggested the use of CWS planted with macrophytes and inoculated by zooplankton. The usefulness of this system is further supported by the natural occurrence of selected species, as it is easy to maintain, has low installation cost, and excellent efficiency in treating wastewater. As both the zooplankton species are preferred live feed for rearing of fish larvae, the present results suggested the use of zooplankton and macrophytes for treatment of wastewater, reduction of sludge, and harvest of live feeds for the aquaculture industry to augment circularity and promote decentralized wastewater treatment.

COVID-19 lockdown affects zooplankton community structure in dolphin appearing site of the River Ganga at Patna

“…Fortnightly, (Monthly during the lockdown) zooplankton samples were collected at both the sampling sites using a 53 µm mesh size nytex plankton net since January 2018 by filtering 45-50L of river water. Zooplankton were immediately fixed in 4% buffered formalin (Prakash et al, 2022) and brought to the laboratory. In the laboratory, the triplicate subsamples were taken on to a Sedgwick rafter counting chamber and was enumerated under the compound microscope (Olympus CX21LEDFS1) for their mean abundances expressed as individuals per liter (Ind.…”

Changes in bacterioplankton and zooplankton communities in response to Covid-19 forced lockdown at dolphin surfacing sites in the River Ganga

“…The microbial communities in the Ganges River and their responses to anthropogenic inputs remain essentially uncharacterized by culture-independent, metagenomic techniques (Sharma et al, 2014; Prakash et al, 2022). Halting human activities in the river is likely to influence the proliferation and distribution of fecal coliform bacteria including Escherichia coli (Miller et al, 2010).…”

“…There is strong evidence to suggest a link between environmental change and infectious microbial community (Epstein, 1995; Daszak et al, 2001, Woodford, 2009; Hwang et al, 2010; Rhyan, 2010). Freshwater microbial populations, as the foundation of freshwater foodwebs and primary biogeochemical agents involved in nutrient cycling, have also attracted (Prakash et al, 2022) attention, but to date there has been considerably less research on riverine dolphin populations than marine microbial communities (Zwart et al, 2002; Rajan et al, 2023). Tracing the significance of various habitat changes for the whole environment is a serious research challenge (Juszczak and Augustin, 2013).…”