A comprehensive review of saline effluent disposal and treatment: conventional practices, emerging technologies, and future potential

Abstract

An ever-increasing volume of saline effluents from industries, oil–gas fields, and desalination plants has resulted in an enormous amount of pollutants with undesirable effects on the environment and human health. Adequate disposal and treatment of these effluents remains a persistent problem and poses significant technical as well as economic challenges. Saline effluents can have considerable environmental impacts, depending upon the sensitivity of the surrounding ecosystems. Conventional disposal techniques mostly suffer from direct or indirect contamination of water/soil and are no longer preferred. As a result, several advanced treatment methods are being considered for sustainable saline effluent management in recent times. In this context, a comprehensive and updated review of conventional methods, along with emerging technologies for disposal and treatment of saline effluent, is presented. Existing treatment approaches, including membrane operation, thermal processes, chemical techniques, and biological methods, are discussed. The application of innovative hybrid processes (combining two or more treatment methods) aiming at lower energy demand and higher treatment efficiency has also been evaluated. Subsequently, emerging sustainable strategies like waste minimization & water recovery, zero liquid discharge, and resource recovery for saline effluents have been examined. The prospect of integrating the renewable energy sources with energy-intensive saline treatment methods towards energy–water–environment nexus is also explored.

Halophyte Plants and Their Residues as Feedstock for Biogas Production—Chances and Challenges

“…This could be implemented by combining percolation of the biomass for dissolving the salt in the percolate and subsequent salt removal from the percolate before its recirculation on the biomass. This requires advanced separation techniques, for example membrane filtration and a subsequent treatment of the salt effluent [117].…”

“…Process efficiency wise, higher specific methane yields were generally achieved for co-digestion of solid organic waste in wet digestion systems at organic loading rates (OLR) below 6 kg-VS m −3 d −1 , while dry mono-digestion systems showed to be favorable at higher OLR [117]. Consequently, the decision of co-digestion vs. mono-digestion for large-scale applications rather depends on the availability of liquid biomass streams in the proximity of the biogas plant treating halophyte biomass.…”

Current available treatment technologies for saline wastewater and land‐based treatment as an emerging environment‐friendly technology: A review

“…Saline wastewater is primarily composed of dissolved mineral salts, hardness causing ions, organic content, nutrients, or other metals and salts such as calcium, magnesium, potassium, sodium, sulfate, and chloride, which are majorly discharged from agro‐food industries, oil and gas industries, tanneries, chlor‐alkali plants, pulp and paper industries, textiles, pharmaceuticals, acid mine drainage, and desalination plants (Guo et al, 2018; Sahu, 2021). The concentration is the amount (by weight) of salt in water and is expressed as “parts per million.” If water has a concentration of 10,000 ppm of dissolved salts, then 1% (10,000 divided by 1,000,000) of the weight of water comes from dissolved salts.…”

Phragmites australis (Reed) as an Efficient, Eco-Friendly Adsorbent for Brackish Water Pre-Treatment in Reverse Osmosis: A Kinetic Study

“…In the RO technique, the applied pressure is chosen according to the degree of salinity of raw water, viz. the total dissolved solids (TDS), to reverse the osmotic pressure [ 6 ]. Thus, the reduction in TDS by adsorption reduces the required pressure and the desalination costs.…”