Biochar has shown to have a positive effects on TDS and sodicity. However, the exact application on how this could be done is yet poorly represented in the literature. One field experimental approach using biochar sustainably produced to reduce TDS and Sodicity from waste water is apply the waste water in the biochar product and monitor progress. I recently conducted a study in Lao PDR using biochar produced from rice husk as a soil conditioner with other treatments to improve the yield of water spinach and soil quality using irrigation ground water.  The results show that biochar decreases both TDS in water and sodicity at the root zone using groundwater as the source of irrigation.

But, biochar could be very effective treating waste water and that is something I will have to engage at some point.

Dear Jeremy,

The following cover the answer to your question.

1-Resources and Environment 2013, 3(5): 101-114

DOI: 10.5923/j.re.20130305.01

Removal of pH, TDS and Color from Textile Effluent by

Using Coagulants and Aquatic/Non Aquatic Plants as (see attached file).

Adsorbents

Ashraful Islam, Arun Kanti Guha*

Department of Textile Engineering, Southeast University, Banani, Dhaka 1213

Abstract The pH of Textile effluent is generally high because of use of many alkaline substances in Textile processing. The total dissolved solids (TDS) are those solids remain as soluble form in Textile effluent. There are several methods

available for removal of TDS and color from Textile effluent such as, ion exchange, coagulation and flocculation, biological decolorization, adsorption etc. Among all these methods adsorption is still a procedure of choice for TDS and color removal.

Several naturally occurring aquatic/non aquatic plants have been used in this work as adsorbents. These were water hyacinth, water lily and bark of plantain plant (banana). All of three plants could be useful for adsorption of pollutants but considering all experimental results the remarkable result was achieved in case of adsorption of pollutants on plantain plant (banana) bark from inlet effluent of Echotex Ltd; Chandra, Gazipur, Bangladesh. Both the pH and TDS removal obtained in this case, pH values were 7.3 (before treatment) and 6.5 (after treatment) and TDS values were 2700 mg/L (before treatment) and 2600

mg/L (after treatment). Different combinations of coagulants were also used for color removal and sludge separation. The best color removal and sludge separation were obtained in case of FeSO4 + CaO.

Keywords pH, Color, TDS, Removal, Textile Effluent, Coagulation, Adsorption

2- A New Process For Sulfate Removal From Industrial Waters

For more details, please use the following link:

http://www.wateronline.com/doc/a-new-process-for-sulfate-removal-from-indust-0001

Many industrial wastewaters, particularly those associated with mining and mineral processing, contain high concentrations of sulfate. These concentrations typically exceed the secondary drinking water standard of 250 mg/L and may be subject to discharge limits between 250 and 2000 mg/L.

The Cost Effective Sulfate Removal (CESR) process was developed to address the shortcomings of other technologies used for sulfate removal. The advantages of the CESR process are:

Low concentrations of sulfate in treated water,

Additional removal of metals and other parameters,

No liquid waste, and

A minimal volume of hazardous solid waste.

Process DescriptionThe most common method for removing high concentrations of sulfate from water is through addition of hydrated lime (Ca(OH)2), which precipitates calcium sulfate:

Na2SO4 + Ca(OH) 2 => CaSO4 + 2 NaOH 

Calcium sulfate, which hydrates to become the common mineral gypsum, has a solubility of approximately 2000 mg/L as sulfate. Sulfate reduction below 2000 mg/L has been possible in the past only through expensive technologies such as reverse osmosis (RO) or ion exchange (IX). Large volumes of liquid waste are generated with RO and IX, which typically create additional treatment and disposal costs. The CESR process can reduce the sulfate concentration in most wastewaters to less than 100 mg/L through use of a proprietary powdered reagent.Addition of the CESR reagent to lime-treated water precipitates sulfate as a nearly insoluble calcium-alumina-sulfate compound known as ettringite. Ettringite formation can also provide a polishing effect, allowing precipitation of difficult-to-remove metals such as chromium, arsenic, selenium and cadmium, often below their respective analytical detection limits. Boron, fluoride and up to 30 percent of the chloride and nitrate in water have also been removed. Metals and other constituents which the ettringite removes are typically not leachable, allowing disposal as a nonhazardous waste. The CESR process uses a sequential design to separate any metal hydroxide sludges from the other precipitates.

The CESR process is an extension of wastewater treatment with lime in that it can meet more stringent requirements for sulfate removal. Lime is inexpensive, readily available and produces stable products which can be reused or disposed in landfills. Unlike treatment methods such as sodium aluminate addition, all of the chemicals added during the CESR process can be precipitated. Water treated by the CESR process typically meets or exceeds recommended drinking water standards for sulfate, metals and other parameters. The process produces a net reduction in total dissolved solids (TDS).

The ability to adjust the CESR process to achieve desired sulfate concentrations allows the process to be economically used by a wide variety of industries. Over 20 treatment plants in Europe now use the process, at flow rates up to 350 gpm. The CESR process essentially consists of four steps:

1. Initial precipitation of sulfate as gypsum

2. Precipitation of metals as hydroxides in a gypsum matrix

3. Additional sulfate removal via ettringite precipitation

4. pH reduction using recarbonation.

3-Technologies to Remove Phosphorus from Wastewater

Peter F. Strom

Professor of Environmental Science, Rutgers University

August 2006

For more details, see attached file.

This brief literature review examines treatment technologies available for

wastewater treatment plants to remove phosphorus. Although it is not meant to be

exhaustive or complete, it does include some of the newest available reports on P

removal.

Treatment technologies presently available for phosphorus removal include:

Physical:

filtration for particulate phosphorus

membrane technologies

Chemical:

precipitation

other (mainly physical-chemical adsorption)

Biological

assimilation enhanced biological phosphorus removal (EBPR)

The greatest interest and most recent progress has been made in EBPR, which has

the potential to remove P down to very low levels at relatively lower costs. Membrane technologies are also receiving increased attention, although their use for P removal has been more limited to date. The question of sludge handling and treatment of P in side streams is also being addressed. 

4-Ion exchange (IX) demineralization, which uses beds of cationic and anionic resins in a pressure vessel similar to media filtration vessel. 

5-ODTMA clay micelles complex; For more details see Rafik Karaman in Researchgate.

Hoping this will be helpful,

Rafik

I think along with other methods you can also go for some cost-competitive biological methods such as Constructed wetlands, It'll not only remove TDS , conductivity and alkalinity but is efficient for other wastes as well at the same time. 

If your waste-water discharge is less than 7 mil. gallon per day (MGD), you should apply constructed wetland. It is very good to consider as a low cost method. 

Dr Tuan Anh Le... can plz elaborate on the performance of filing material on the constructed wetland?

Dear Jeremy,

at open pit mines of Kuzbass (Russia) we use an artificial filter arrays, e.g. overburden dumps. Some results of using of this technology you can see there:

https://www.researchgate.net/publication/283569947_Justification_complex_purification_technology_open-pit_mines_wastewater

also till the end of Dec.2015 in Pollution Research another paper on this problem ("The low-cost technology of quarry water purifying using the artificial filters of overburden rock") will be out of print.

Conference Paper Justification Complex Purification Technology Open-pit Mines...

Depending on the loading rate of TDS and volumes to be treated, you may either prefer a (sand) filtration system with automated backwashing (fairly cheap) or a percolation wetland system. If the loading rates are very high to start with, you may prefer to start with a primary settling tank to already clarify to a certain extent. The use of coagulants/flocculants will increase TDS removal yet at increased cost. So in the end, it will all depend on the actual circumstances to determine which option is best.

Dear Sunil and all,

Pls, read my PhD thesis for your reference.

Valsa,

How do you recirculate using gravity?

How do stones remove TDS?

Do you have any references to this method?

Regards,

Jeremy

Constructed Subsurface flow wetland may be a low cost solution for removing TDS.

Hello Jeremy,

Nice to be in touch again but now on a different platform. I always appreciate your pertinent comments in various groups on LinkedIn.

Knowing that TDS = total dissolved solids, the first step is to remove all non-mineral dissolved solids by advanced biological treatment (without adding any chemicals other than nutrients if/as required). This results in ultra-low TOC, COD, BOD, TSS, turbidity (NTU) and SDI (silt density index) which minimizes irreversible fouling and power consumption of NF/RO membranes and doubles their economic lifetime. In the second step, some of the minerals could be removed by precipitation and/or air stripping. Finally after UF/cartridge pre-filtration and conditioning, the remaining TDS is retained by partial or full RO filtration as needed. I would like to add that some minerals such as sulfates, nitrates, ammonia, ... can also be removed in the first step by advanced biological treatment. In this way, we develop, design and realize tailored high grade water reuse systems with over 90% overall water recovery = less than 10% water loss at the lowest operating and lifecycle cost. Depending on the scale/capacity and on the quality of the source water the treatment steps 1 and 2 could be skipped as to minimize investment cost.

Regards, Bruno

Dear Bruno,

Thank you. Good to meet you, too, on a different platform. We had membrane filtration as our high-cost solution, and were looking to see if there was anything cheaper that we had missed.

A mass balance on the likely sources of the TDS was that it was the product they were making, rather than incidentals (e.g. cleaning chemicals), so that upstream changes were not feasible.

There isn't the land area for reed beds, so we recommended looking at membrane filtration. They already had biological treatment so were in specification for traditional parameters, but not for TDS. But it's good that someone with your depth of experience would choose the same route, with more detail than we had - we devolved details to whoever would be chosen as the membrane supplier.

All the best,

Jeremy

Depending on the TDS composition and level at the outlet of the biological treatment and the target TDS, it could still be possible to achieve this TDS target without adding membranes as already indicated in the biological treatment (step 1) and/or in the post treatment (step 2).

Thank you. Not sure how they would be removed in the biological stage if it is there and they are not being removed. The BOD was low in the effluent.

Precipitation was something we missed; the nature of the chemicals was 'TDS' so we could have asked for a more detailed analysis. For next time ... they only had to get TDS down to the levels in the river.

Regarding the organics in the TDS, we achieve BOD < 3 ppm and COD < 30 ppm on municipal sewage and industrial wastewater with BOD/COD > 0.5.

We biologically reduce sulfates SO4-- to sulfides for either direct precipitation by  suitable cations in the wastewater or for partial biolgical oxidation to element sulfur S° which precipitates as well.

Nitrates NO3- , nitrites NO2- and ammonia NH4+ are simultaneously removed via biological oxidation-reduction using the nitrite shortcut which includes direct anoxic/anaerobic ammonification (anammox).

Hello all I am working on Wastewater ETP Plant of a textile mill and which is of the biological treatment based. TDS content is very high (approx. 10,000 ppm) in-fluent water source and 5,000 ppm at the outlet.

Anyone can help me out regarding this matter ? Can i use different adsorbent like silica or sawdust in biological treatment? Will it harm to bacterial degradation?

Huma Raza

The fact that ca. 5000 ppm TDS is removed by the biological treatment seems to indicate that at least 50% (but probably more) of the TDS is organic.

According to my experience with the in-depth assessment of over 20 large textile ETP's (incl. several denim plants) in Bangladesh within our in-depth CPA (cleaner production assessment) on behalf of the IFC (Worldbank) in 2012-2014, well designed and operated biological treatment removes almost all organic TDS including most residual dyes. Adding inert absorbents such as silica, sawdust, ... may adsorb some of the organic TDS fraction but will not remove the inorganic (mineral) TDS fraction (salts) and will adversily affect the capacity of the active biosludge. As to remove recalcitrant (hard to biodegrade) organics such as dyes and some finishing chemicals we regenerate the biosludge flocs as to boost their adsorption capacity (similar to activated carbon) and their ability to biodegrade these 'hard' organics by suitable exo-enzymes produced by the selected and adapted micro-organisms in the biosludge.

As to proceed, I would recommend to first split both the ETP inlet and outlet TDS (Total Dissolved Solids) in an organic and in a mineral fraction and determine the amount of sulfates, ammonia, nitrate/nitrite and chlorides in the mineral fractions.

Bruno Peeters Sir, this biological method for removal of TDS does it involves the use of bacteria? If yes, sir can you please recommend some of the bacteria.

Prosper .E Ovuoraye

Yes most of the micro-organisms in healthy active biosludge are bacteria which are selected (by enhanced natural selection) and adapted to the specific wastewater composition (incl. organic + mineral TDS fractions) and operating conditions. If necessary we enrich the microbial population with fresh activated biosludge from other ETP's treating similar wastewaters.

According to our experience, adding commercially available bacteria directly in most industrial biological ETP's would have little effect because these will barely get integrated in the microbial flocs and get largely washed out with the final effluent.

If its industrial waste water (effluent )like steel processing the most effective is lime neutralization, softening with soda ash, Microfilters , RO , vaporization . Because of heavy metal and acid in effluents the processing is costly and needs proper systems to have ZLD. (Zero liquid discharge, complete reuse of water and only make up fresh water use)

if waste heat/ solar heat, is available then most economical TDS removal system would be Humidification -Dehumidification,

Humidification-dehumidification is a thermal desalination cycle that operates by heating saline water using waste heat /solar thermal energy, evaporating the heated water using a humidifier and finally condensing the water vapor to form fresh water in the dehumidifier.

The Natural analogy the above system is, evaporation of water from sea by winds and precipitation in the form of rain.

Its very capital intensive, consume lot of space and we have explored.

We are in search of solution which are other than RO plant, soda ash and caustic use,

Knowing that TDS = total dissolved solids, the first step is to remove all non-mineral dissolved solids by advanced biological treatment (without adding any chemicals other than nutrients if/as required). This results in ultra-low TOC, COD, BOD, TSS, turbidity (NTU) and SDI (silt density index) which minimizes irreversible fouling and power consumption of NF/RO membranes and doubles their economic lifetime. In the second step, some of the minerals could be removed by precipitation and/or air stripping. Finally after UF/cartridge pre-filtration and conditioning, the remaining TDS is retained by partial or full RO filtration as needed. I would like to add that some minerals such as sulfates, nitrates, ammonia, ... can also be removed in the first step by advanced biological treatment. In this way, we develop, design and realize tailored high grade water reuse systems with over 90% overall water recovery = less than 10% water loss at the lowest operating and lifecycle cost. Depending on the scale/capacity and on the quality of the source water the treatment steps 1 and 2 could be skipped as to minimize investment cost.

Interesting. Does this Biological treatment is workable for effluent which contains HCl, Sulphates and heavy metals like iron, Mn etc. Also is this treatment is cheaper that use of lime and caustic soda?

Dinesh Gudadhe

Biological treatment is most sustainable (maximum performance with minimum energy, chemicals and waste) and hence most economic (lowest lifecycle cost).

It operates in a 5 - 9 pH range (optimally around pH 7) and is constrained mainly by high levels of salinity (chlorides, sulphates, ...) but got good performance in full scale plants at up to 30 g/l = 30 000 ppm chlorides. Most heavy metals incl. Fe and Mn can be removed by precipitation together with sulphates. We provide advanced biotechnology and over 45 years worldwide expertise incl. in India ref. www.modelengineering.eu . I would be happy to send you more details via email.