Good progress has been made during the first year of the project in developing systems to reduce salt use in hide and skin preservation and processing. Most of the work has so far been associated with laboratory trials although significant industry trials have also been completed. In India, trials have used both goat skins and hides and woolskins have been used in Australia.

Air drying and dry-salting of skins
The first aim of this Objective is to develop and demonstrate skin drying techniques that will be acceptable to tanners and will replace conventional salting.

Encouraging laboratory air-drying trials have achieved good preservation and insect control at 30C. Pre-treatment on the flesh side of skins with low levels of several additives, with or without low levels of salt, provide protection during the drying phase and aid in the re-hydration of dried woolskins. This is particularly important in fatty areas and areas with edge-curl. Effective additives include low-cost combinations two or three of the following compounds: boric acid, borax, zinc oxide, magnesium oxide, sodium carbonate, sodium bicarbonate and sodium chloride.
Tanners are assessing the systems and industry trials are planned.

In 2003, TDS is an even more critical issue for Tamil Nadu tanneries than in 2002. The tanners accept that they will incur significant costs in the next two years to achieve TDS reduction. The current intense financial pressure on tanners to reduce TDS means that if the drying technology achieves good leather quality, tanners are likely to be willing to pay the necessary incentive for good quality dried skins. The tanners will also accept any increased tannery processing costs such as a modified soak. Technology transfer and training are likely to be the major socio-economic issues for the Project. However, successful skin drying techniques must be demonstrated before tanners will seriously consider implementation. It is anticipated that the progress of the CLRI drying trials will be reported to industry at LERIG, (Leather Research Industry Get-Together) January 2004 at CLRI. It is proposed that a workshop will be held to coincide with LERIG where all aspects of the technology and implementation will be discussed. CLRI is currently involved in an All India Survey on Hides and Skins from January 2003 to December 2003 and results of this survey will also be presented at the workshop and implications for market practices will be discussed.

Short term preservation with chemicals
The original objective was to evaluate short-term preservation for Indian and Australian tanneries to protect hides for 7 days before processing. There has proved to be a demand in India for preservation of goat skins for 3 weeks and consequently the project is now looking at systems to give longer preservation times.
Encouraging results have been achieved with several combinations of the effective additives used for drying. (See above).

Although chilling is already being used for short- term preservation in Australia, it does not appear to be feasible for industrial adoption in India.

Direct chrome liquor recycling (DCLR) including recovery and reuse of excess liquor to reduce TDS.
To enable development of DCLR for India, the effect of pickle pH and temperature on chrome complexes and chrome penetration has been established for Indian chrome powder. Now laboratory trials of DCLR are in progress and industry trials are being planned.

The use of a number of solar evaporation systems to enable Total Chrome Liquor Recycle, which would recycle all salts, has been investigated and they will not be economically viable. It is proposed that Rapid Spray Evaporation is now investigated.

To evaluate improved pickle recycle systems for TDS reduction.
Instead of conducting initial laboratory trials as planned, the Australian collaborating woolskin tanner agreed to continue recycling commercial pickle liquors past the usual 20 uses. The liquors and the leather quality were monitored and it has been found possible to continue to use the liquor for more than 100 cycles. No liquor clarification has been necessary. This is a significant Project development which has seen the implementation of a simple, very effective technology which significantly reduces tannery salt use and discharge.
Laboratory pickle recycle trials for vegetable tanning are in progress in India and industry trials have started.

Year 2 (01/07/2003-30/06/2004)
Hide and skin preservation
It now seems unlikely that drying or dry-salting will be adopted for skin preservation. Low salt preservation and chilling will both greatly reduce salt use and are far more likely to be implemented.
Low salt preservation
Rather than drying skins in India, it is more feasible for the first handlers of the skins to salt unopened skins as usual with about 20 per cent salt by weight. Collection centres, often already controlled or influenced by tanners, will apply additives as necessary to preserve the skins for 7 to 21 days as required. This will reduce salt use 3 to 4-fold, from 60-80 per cent, and there will be few salt crystals on the skins and little solid salt waste. Evaporation of soak liquors will be required, as is the case at present. As waste salt will be significantly reduced, all the evaporated salt should be able to be re-used or used as a fertiliser for coconut palms.
The Indian Environmental Charter excludes the use of boron compounds. The concentration of such compounds in Indian tanning centres could lead to build-up of damaging levels in soils. Trials have shown the most suitable additives to be magnesium oxide or naphthalene.
A large Tamil Nadu tannery is very supportive of the project and is trialling low salt preservation of skins. They have more than 10 collection centres and the new system is initially being trialled in Delhi.
In Australia, a skin merchant and a major woolskin tanner are collaborating with CSIRO in commercial trials of low salt preservation. Several additives have been compared, including boron compounds which are already widely used in Australia. Low salt preservation could reduce salt use seven-fold.
Chilling of hides and skins to replace salting
Chilling now appears to be viable for some hides and skins in parts of India. CLRI have done some trials and cost calculations and is purchasing a mobile chilling unit for industry trials and demonstrations. This will initially be used for chilling hides in Kerala and transportation to KKSK, a large hide tannery in Erode. When trials have been completed, KKSK plans to have chillers in both Kerala and Erode and to use insulated trucks for transport. KKSK will first prove the technology and then purchase chillers. It is possible that 15 Erode Tanners could combine in a chilling enterprise.
Socio-economic issues
The major socio-economic issues for the Project were originally considered to relate to adoption of air drying of skins. However, the low salt preservation will be far easier to implement. The technology transfer and training will be easier than anticipated because the tanners will be the champions of the new technology and tannery technicians will be involved in the training of their skin suppliers. The collaborating tanners say that once the technology is proven to them, they will adopt the new systems, champion them, and the rest of the industry will follow.
An Industry Workshop on Proposed Preservation Changes was held in April to discuss implications for market practices and socio-economic issues. There were 28 participants including tanners and hide and skin dealers. Participants agreed that there must be change and gave positive feedback for the project. It was agreed by the dealers that the proposed low-salt preservation would entail little change for first handlers of skins and the main issue was who would pay if costs increase. One possibility raised was that to bring about change, the tanner could pay more for skins with less salt and good preservation and less for skins with excess salt. The costs associated with chilling were discussed and it was generally accepted that those who gain from the development should bear the cost. Chilling will first be tried with hides slaughtered in Kerala and tanned in Erode but it is a possibility for other centres from Bangalore to Ranipet. Raw skin dealers said they could not invest in a chiller but tanners may do this and it is a possibility that the Government may provide loans which industry would repay. Costs and benefits first need to be determined.
Direct chrome liquor recycling
Initial commercial trials at a major tannery have been successful.
Pickle Recycle
A Dindigul tannery which usually discharges pickle liquor after each use has successfully done trials for eight uses and is advocating the system to other tanners. Equipment to facilitate recycling is being installed. Recycling in Australia has been successfully extended and has been monitored for 200 uses.

In 2005 the TDS situation in Tamil Nadu has become even more critical for the tanning and textile industries due to a Court Ruling. Tanneries in Erode not discharging to a CETP must meet 2,100 ppm TDS or install Reverse Osmosis (RO) by the end of August 2005 at high capital, operating and maintenance costs. In future CETPs must meet 2,100 ppm TDS or have zero effluent discharge which will again mean installation of RO. RO concentrates will be evaporated. It is expected that the ruling will subsequently apply to all TN tanneries.

Small tanneries are expected to go out of business. Even some larger tanneries will not have the technical staff to run RO. It is anticipated that there will be problems with membrane fouling in wet- blue tanneries.

No answer has been found for disposal or use of the large amounts of the recovered evaporated solids. No disposal options are available for these mixed salts; they will be piled at tanneries and it is likely that during the monsoon they will be dispersed into the environment.

The great advantage of the four ACIAR Project developments is that salt use is reduced and the problem of recovered salt is greatly reduced. Cleaner processes are better than end-of-pipe treatments.

Hide and skin preservation
Low salt preservation
To reduce TDS, first handlers of Indian goat skins will salt unopened skins as usual with about 20% salt by weight. This will reduce salt use 3 to 4-fold and there will be few salt crystals on the skins and little solid salt waste.

A major tannery has now conducted trials at 3 of their 10 collection centres throughout India. Pilot trials using 20% salt and 2% magnesium oxide have given good preservation and with a modified soak have produced good quality leathers but there has been a problem with the flesh sides of the low salt skins sticking together. In summer this was a significant problem because the sticking made opening up of the skins very difficult. Trials are now being undertaken where the skins are pulled flesh out before transport as this could well overcome the problem. CLRI are doing trials comparing several modifications including the use of other salt additives which have previously given satisfactory preservation.

An Australian skin merchant and a woolskin processor are continuing to collaborate with CSIRO in commercial trials of flat salting with low salt levels and sodium fluoride plus boric acid as additives. Low salt preservation can reduce salt use 4 to 7 fold. The most recent trials were started in December 2004 and after 6 months the low salt skins were as good as or better than the controls. Some of the skins will be kept for a year before processing.

Chilling
The main advantage of chilling is the salt reduction of 40-50% salt on hide weight. For 1 tonne hide, it is possible that 500 kg less salt is used and discharged and disposed of as solid waste. For skins the salt savings are up to 80% salt on skin weight.

It is expected that in India the system will need:

Blast chillers with generators and additional chilled storage areas at collection centres.
Insulated trucks, in some cases with an air conditioner, for transport.
Chilled storage areas for holding hides at tanneries before processing

This system has been commercially costed and the costs compare favourably with overall costs of salting and recovery of evaporated salt.

CLRI has purchased a mobile chilling unit for industry trials and demonstrations. The first trial in Erode was very successful. The wet blue quality was assessed as being no different to usual production. The hide dealer and tanner involved, KKSK, are very impressed with chilling. Goatskin tanners will do trials once the system has been adopted for hides.

Direct Chrome Liquor Recycling (DCLR)
Commercial trials at KKSK have been successful and the problem encountered in an earlier trial has been overcome. Trials at another tannery are planned. KKSK will implement the process once chilling of hides has been adopted. They should then be able to achieve zero discharge.

Pickle Liquor Recycle (PLR)
A Dindigul tannery which used to discharges pickle liquor after each use has successfully done trials for 15 uses and has now adopted the system for regular processing. Equipment to facilitate the recycling has been installed and the tanner is demonstrating the system to other tanners. A simple system which requires no additional equipment, suitable for pickling in paddles but not drums, will also be demonstrated. The pickle liquor is kept in a designated pickle paddle.

Project Review
In the January 2005 Project Review, the external reviewers recommended that the project outcomes should considerably reduce tannery salinity problems. They recommended that the project should be extended for two years to further develop, consolidate and magnify the benefits of the results.

In 2006 the TDS situation in Tamil Nadu (TN) has become even more critical for the tanning industry than it was in 2005. The Erode Court Ruling of 2005 now applies to all of Tamil Nadu. Tanneries not discharging to a CETP must meet 2,100 ppm TDS or install Reverse Osmosis (RO) at high capital, operating and maintenance costs. By the end of 2007, CETPs must meet 2,100 ppm TDS or have zero effluent discharge which will again mean installation of RO. This means that all TN tanneries or their CETPs require RO. RO concentrates will be solar evaporated.

Tanneries in Erode have installed RO but those in wet-blue plants are not yet operational. A number of larger TN tanneries processing hides and skins from wet-blue to finished leather have found that the use of the low salt permeate from RO for processing provides considerable chemical savings in dyes and other expensive chemicals, due to the low TDS. These savings offset costs. In wet-blue plants there are no chemical savings and it is anticipated that there will be problems with RO membrane fouling in wet- blue tanneries, except for goat skins when the hair is saved.

A recent audit has found that most Erode tanneries have inadequate solar evaporation systems and improvement of the systems will be another major expense. No answer has been found for disposal or use of large amounts of the recovered evaporated salts. Other than for application to coconut palms in Kerala, no disposal options are available for these mixed salts; they will be piled at tanneries and it is likely that during the monsoon they will be dispersed into the environment.

The advantage of the four ACIAR Project developments is that salt use is reduced and the problem of recovered salt is greatly reduced. Cleaner processes are better than end-of-pipe treatments.

Hide and skin preservation
Low salt preservation
To reduce TDS, first handlers of Indian goat skins will salt unopened skins as usual with only 20% salt by weight. This will reduce salt use 3 to 4-fold and there will be few salt crystals on the skins and little solid salt waste. An additive must be used with the salt to achieve good preservation.

The additive used with the salt in industry trials up until July 2005 was magnesium oxide, but there was a problem with the flesh sides of the skins sticking together. In summer this was a major problem because the sticking made opening up of the skins very difficult. After further CLRI laboratory trials, the tannery collaborating on the low salt system has now achieved a good result with skins preserved with 20% salt and 2% sodium carbonate and held for over 3 weeks in hot summer conditions. The 50 treated skins were more moist than the control skins but they were well preserved and could easily be turned flesh out and opened. A trial with 500 skins is now planned.

An Australian skin merchant and a major woolskin processor collaborated with CSIRO in a successful, one year commercial trial of flat salting with low salt levels and sodium fluoride plus boric acid as additives. Very unfortunately the woolskin processor, which was under pressure to reduce TDS, closed Australian operations in December 2005. There are now no large woolskin tanneries in Australia and most skins are conventionally drum salted and exported to China. The skin merchant does not have a market for the flat salted skins as they require more labour to produce and are therefore slightly more expensive.

It is very difficult for Australian tanneries to compete with China and unfortunately the other Australian tannery collaborator also closed at the end of 2005. The pickle liquor and chrome liquor recycling systems had been very successful in reducing effluent TDS.

Chilling
The main advantage of chilling is that salt is not used in preservation. For processing 1 tonne of hide, it is possible that 500 kg less salt is used and discharged and disposed of as solid waste.

In India the system will need:
Blast chillers with generators and additional chilled storage areas at collection centres.
Insulated trucks, in some cases with an air conditioner, for transport.
Chilled storage areas for holding hides at tanneries before processing

The CLRI mobile chilling unit has now been used for three industry trials. All the trials in Kerala and Erode have been very successful with wet blue quality being assessed as no different to usual production. KKSK, the largest hide tannery in Erode, has done 2 trials and is very impressed with chilling. KKSK sees that eventually all Erode tanners will use chilling. At the Erode workshop in July 2006, 6 more tanners signed up to do trials with the mobile chiller. Full implementation of chilling by KKSK is being investigated.

Direct Chrome Liquor Recycling (DCLR)
Commercial trials at 4 tanneries have been successful. No tanneries have yet implemented the process but now that chrome prices have increased and TDS discharge is more critical, the benefits have increased and several tanneries are planning implementation or scaling up trials.

Pickle Liquor Recycle (PLR)
One Dindigul tannery which used to discharges pickle liquor after each use has successfully adopted the system for regular processing. The tanner is demonstrating the system to other tanners. Two other tanneries have done trials but have not yet implemented the system.

Background

In 2007 the salinity or TDS (Total Dissolved Solids) situation in Tamil Nadu (TN) remains critical for the tanning industry. Common Effluent Treatment Plants (CETPs) must meet 2,100 ppm TDS or have zero effluent discharge which means installation of RO (Reverse Osmosis). Therefore all TN tanneries or their CETPs require RO. RO concentrates are to be solar evaporated.

Most Erode tanneries have inadequate solar evaporation systems and improvement of the systems will be another major expense. No answer has been found for disposal or use of large amounts of the recovered evaporated salts. Other than for application to coconut palms in Kerala, no disposal options are available for these mixed salts; they will be piled at tanneries and it is likely that during the monsoon they will be dispersed into the environment.

In November 2006, three Erode tanneries were closed down on account of pollution problems. At present the main focus seems to be on zero discharge rather than TDS and salt use reduction measures, though both are intertwined. Eventually the Government and industry must realize this. Both approaches will necessary to achieve satisfactory environmental outcomes: low TDS in effluent and less waste salt.

The advantage of the four ACIAR Project developments is that salt use is reduced and the problem of recovered salt is greatly reduced. Cleaner processes are better than end-of-pipe treatments. The developments could make zero discharge from some tanneries feasible.

To achieve significant salt use reductions in India, there will need to be considerable uptake of low-salt preservation of skins and chilling of hides. The proposed low-salt preservation will entail little change for first handlers of skins but greater care will be required to ensure even salt application. There will be resistance to change. One possibility that may bring about change: the tanner could pay more for skins with less salt and good preservation and less for skins with excess salt.

The costs associated with chilling will be considerable. To achieve industry implementation, Government may need to provide funding and incentives to tanneries as have been available for RO installations.

Progress in industry implementation

Hide and skin preservation
Low salt preservation
Studies have demonstrated hides can be preserved with only 20% salt by weight. This will reduce salt use 3 to 4-fold and there will be few salt crystals on the skins and little solid salt waste. An additive must be used with the salt to achieve good preservation. The additive used with the salt in industry trials up until July 2005 was magnesium oxide, but there have been problems with the flesh sides of the skins sticking together in summer. The tannery collaborating on the low salt system has achieved good results with skins preserved with 20% salt and 2% sodium carbonate. A larger trial with 750 skins has also given encouraging results.

Chilling
The main advantage of chilling is that salt is not used in preservation. For processing 1 tonne of hide, it is possible that 500 kg less salt is used and discharged and disposed of as solid waste.

In India the system will need:
Blast chillers with generators and additional chilled storage areas at collection centres.
Insulated trucks, in some cases with an air conditioner, for transport.
Chilled storage areas for holding hides at tanneries before processing

It is considered that the best way to achieve implementation of chilling is to have one system operating as a demonstration. KKSK Tannery in Erode is the best tannery to do this. After major recent capital expenditure, including installing RO and extended solar evaporation, KKSK is meeting TDS requirements and has achieved zero effluent discharge. Kerala coconut farmers take the recovered salts. Rafiq of KKSK considers that eventually all Erode tanners could use chilling. KKSK wants to implement chilling and to demonstrate the technology to the industry.

CLRI has applied for funding from Government agencies including the Central Pollution Control Board for the implementation of chilling.

Direct Chrome Liquor Recycling (DCLR)
To implement DCLR and demonstrate the technology to the industry, a plant is being installed at Abdul Azeez Tannery (SAA), Erode.

Pickle Liquor Recycle (PLR)
One Dindigul tannery which used to discharge pickle liquor after each use has successfully adopted the system for regular processing. The tanner is demonstrating the system to other tanners.