Fertigation with domestic wastewater: Uses and implications

Constructed wetlands for textile wastewater remediation: A review on concept, pollutant removal mechanisms, and integrated technologies for efficiency enhancement

Textile industries are among the ecologically unsustainable industries that release voluminous wastewater threatening ecosystem health. The constructed wetlands (CWs) are low-cost eco-technological interventions for the management of industrial wastewaters. The CWs are self-sustaining remediation systems that do not require an external source of energy and encompass simple operational mechanisms including biological (bioremediation and phytoremediation), chemical, and physical processes for pollutant removal. This review idiosyncratically scrutinizes the recent advances and developments in CWs, and their types employed for textile wastewater treatment. The major focus is on mechanisms involved during the removal of contaminants from textile wastewater in CWs and factors affecting the performance of the system. The article also discusses the State-of-the-Art integrated technologies e.g., CW-MFCs/algal ponds/sponge iron coupled systems, for the performance and sustainability enhancement of CWs. All the important aspects together with the technology amalgamation are critically synthesized for establishing suitable strategies for CW-based textile wastewater treatment systems.

Fish-processing effluent discharges influenced physicochemical properties and prokaryotic community structure in arid soils from Patagonia

Along the Patagonian coast, there are processing factories of marine products in land that produce fish-processing effluents. The aim of the present study was to assess the physicochemical properties and the prokaryotic community composition of soils receiving fish-processing effluent discharges (effluent site-ES), and to compare them with those of unaltered soils (control site-CS) in the arid Patagonian steppe. We analyzed soil prokaryotic communities (using amplicon-based sequencing of 16S rRNA genes), soil physicochemical properties and fish-processing effluent characteristics. Soil moisture, electrical conductivity (EC), total and inorganic C were significantly higher in ES than in CS (p < .05). Effluent discharges induced a decrease in the total number of operational taxonomic units (OTUs) and in the Shannon diversity index (p = .0009 and .01, respectively) of soil prokaryotic community. Proteobacteria, Actinobacteria and Acidobacteria were the dominant phyla in CS, while ES soil showed a more heterogeneous composition of phyla. Linear discriminant analysis (LDA) effect size (LEfSe) analysis showed that fish-processing effluent discharges promoted an enrichment of Firmicutes and Bacteroidetes, which are active contributors to organic matter mineralization, along with a decrease of oligotrophic phyla such as Acidobacteria, Chloroflexi, Armatimonadetes and Nitrospirae, commonly found in nutrient-poor arid soils. The concentrations of inorganic C and ammonium, the EC and the soil moisture explained 73% of the total variation within the community composition. Due to its salinity and nutrients, fish-processing effluents have potential mainly for native salt-tolerant plant irrigation, however the impacts of soil prokaryotic community shifts over plant growth remain to be determined.

Capacitive deionization of a RO brackish water by AC/graphene composite electrodes

A feasibility study for water recycling and reuse of a reverse osmosis (RO) brackish wastewater by capacitive deionization (CDI) was carried out in the present work. Palm-shell wastes enriched in carbon was recycled to yield valuable activated carbon (AC) that has advantages of high surface area, high specific capacitance, and low electrical resistance as the CDI electrodes. The GAC prepared by dispersion of AC in the graphene (rGO) layers has a high surface area and electrical conductivity for CDI. The GAC electrodes have increasing electrosorption efficiencies from 1.6 to 3.0% during the repeated electrosorption-regeneration cycles under +1.2 → 0 → +1.2 V while the efficiencies the AC electrodes decrease from 2.7 to 1.6%. It is clear that the GAC-based electrodes have a better electrosorption efficiency and stability in, for example, the three repeated electrosoption-regeneration cycles for CDI of the wastewater. This work also exemplifies that the AC recycled from biomass such as palm-shell wastes can be used in CDI electrodes for recycling and reuse of wastewater.

Organic waste vermicomposting through the addition of rock dust inoculated with domestic sewage wastewater

The aims of the present study are to assess the organic waste vermicomposting process (cattle manure mixed with tannery sludge) by using inorganic waste (rock dust) inoculated with treated domestic wastewater sewage, as well as the vermicompost application in Ruellia brittoniana seedling production. Different proportions of organic and inorganic waste moistened (or not) in wastewater were vermicomposted (by Eisenia foetida) for 120 days in the first stage of the experiment. Statistically significant earthworm density increase was observed between the 60^th and 90^th experimental vermicompositing days in all the assessed groups. There was decreased E. foetida population density after 90 days. The K, P, TOC, C/N ratio and Ca, Na and Mg concentrations significantly decreased at the end of the vermicompositing process in comparison to the initial concentrations identified in most treatments. On the other hand, there was pH and N, Fe, Zn and Mn concentration increase in most of the vermicomposts assessed at the end of the experiment. All plants grown in soil containing vermicomposts presented higher Dickson Quality Index (DQI) than the control group, which was cultivated in soil containing commercial topsoil. Plants grown in soil containing 100% cattle manure and tannery sludge, moistened in treated domestic wastewater sewage, showed the highest DQI. Thus, the vermicomposting waste used in the present study, which was inoculated with treated domestic wastewater sewage, is an interesting vermicompost production technology to be used in ornamental plant production.