In safely and continuously irrigating with saline water there are many considerations - water salinity, Sodium Adsorption Ratio, presence of contaminants e.g. Fluoride, maintaining hydraulic conductivity and structural integrity of selected soils for irrigation, capacity for adequate leaching of salts through and beyond the soil profile, adequate depth to closest aquifer to ensure nil/minimal impact on groundwater salinity. In Queensland there are coal seam gas water irrigation projects that have been safely irrigating agroecosystems involving salinity tolerant forests and grazed pastures at about 8 ML/ha/yr of 4000 uS/cm EC / SAR 25 water for 12 year. Managing irrigation water and or soil water bicarbonate through sulphuric acid and gypsum pre-treatment of water to be pumped or regular soil application of agricultural grade gypsum and bentonite sulphur to soil surfaces, backed with regular soil monitoring, has been critical for success. These systems have involved Australian Soil Orders - Tenosols, Kandosols, Dermosols and Vertosols. Irrigating 12000 mg/L TDS water would require dilution with appropriate quantities of high quality surface or groundwater, ensuring all contaminants e.g. F fall within regulatory limits and that the proposed irrigation regime is modelled to ensure adequate leaching of applied salts through the soil profile and there will not be measurable impacts on underlying aquifer salinity. Depending on choice of crop plant foliar tolerance of irritant salinity may be less than for root uptake. This may cause preference for centre pivot drop tube or drip irrigation versus sprinkler irrigation systems. In Queensland flood irrigation of the above saline water would require a specific feasibility study and may be excluded under current regulatory guidelines.
Day Hi from BKK Thailand. This is the terrible topic and still need the method to remove TDS. I have experience in Struvite which be generated after operated RO to recycle wastewater in cassava plant. There are mainly 3 ways,
Firstly, using this watewater for cooling tower.
Secondly, using huge volume of treated wastewater to dilute.
Thirdly, Create Struvite by using RO more than 3 time untill become to be crystallization.
Generally , only high salinity –Tolerant plants can be irrigated with concentrate of salinity higher than 2000mg/l. Such plants can not only tolerate high salinity but also extract salt from the water and store it in its tissue or leaves.
First of all, it is to be ascertained whether there is a need for irrigation of water for salinity tolerant vegetation nearby the site . It would be cost effective only if concentrate is blended with fresh water source or waste water to reduce its salinity to levels acceptable for irrigation.
There are plants can be grown using concentrate having salinity more than 2000mg/l ( In Middle East etc) .
It also depends on site specific soil conditions, effect on soil due to the presence of Trace metals in the concentrate and its Toxicity if any caused by specific ion , and the impact on the Ground water quality etc
It needs a thorough site specific study before taking a call.
Is this SWRO, BWRO, Tile Water RO, what was the raw water source? This determines the quality of the reject water and its potential uses. Is the TDS salts NaCl), Se, other?
An indisputable and fail safe way to use the reject water is for flushing in a toilet. Have a toilet built or connect the reject water pipe to water tank of an adjacent toilet.