Tartaric Acid Anodising
Tartaric Sulphuric Anodising (TSA) AIPI 02-01-003, a replacement for Chromic Acid Anodising, provides superb corrosion protection and paint bonding properties for a wide range of aluminium alloys. TSA is becoming the standard for the Aerospace and Defence industries, replacing the environmentally unacceptable Chromic Acid Anodising.
There are some process issues which need to be addressed in terms of metal chelating in the subsequent waste water system and microbiological activity in both the TSA solution and water rinses post anodising.
- Microorganisms destabilise the chelates in the TSA Bath
- Bio-fouling in the rinsing process after TSA
- Waste water: poor metal precipitation and high COD-load cause breach of discharge limits
Fig. 1 – Fungal and Bacteria fouling on rinse tank walls
Fig. 2 – TSA solution filtration shows microbiological activity even in a high acid background
TSA Microbiological Contamination Control
Rinse tank walls offer a large surface area for microbiological slime films to grow. The Microspear TM UV system irradiates both the tank wall and the rinse water to maintain a clean environment for rinsing without the risk of particle contamination on the surface of high value aerospace components.
Micro-organisms establish themselves after several weeks of operation and start to build up a biological layer on the bath walls and the internal piping leading to a bio fouling of the TSA process.
A Microlight® – thin-film sanitation unit can control the bacteria and spore count, stabilising the TSA bath. All our Microlight® UV disinfection reactors use rotational flow. This guarantees high turbulence which prevents deposits and ensures thorough UV sterilisation as the liquid passes through the reactor.
Tartaric anodising solution ingredients are highly bioavailable and lead to strong bio-fouling, Belmar offer a cost effective solution with in tank UV disinfection combined with high intensity UV disinfection for TSA solution.
TSA Waste Treatment Technology
Waste Water Treatment from Tartaric Acid Anodising is required to prevent the following operational issues:
- Chelating of metals – Discharge consent
- Biofouling in the waste water treatment plant with associated floating slime and odour issues
Belmar has addressed the issues of treating chelated waste solutions with the application of Advanced Oxidation. The process uses hydrogen peroxide in combination with UV to produce hydroxyl radicals that subsequently oxidise species such as Tartrate to a level where after treatment the wastewater can be simply treated with the classic lime or caustic precipitation.