The epicentre of the Beier system is the washplant (above) and ‘reactor’ (right). By the point the shredded material flake arrives at the wash stage a considerable portion of the dirt (including sand clinging to bottles and containers after collection from landfill) has been removed. The PET particles, with a specific density of 1.37g/cm³, sink and most of the remaining impurities such as label material floats

Zibo Containers’ washplant for PET thermoforming goods goes into operation

ZIBO Containers is busy with one of the biggest plastics recycling projects to date in South Africa, that of the commissioning and trialing of a washplant to clean PET thermoformed containers – with the aim of reusing the resulting rPET in the production of food-grade thermoformed packaging containers.

By late-November Zibo an estimated 6-8 tons of material was going through the washplant a day, running a single shift, and the material produced is already entering its thermoformed tray production lines.

The big capex project follows on the 2020 commissioning of an Erema Vacurema system, which is the next step after the washplant stage. The Erema system processes the hot washed flake from the washplant and produces rPET according to EFSA (European Food Safety Authority) standards for reuse in trays and punnets.

The perceived deterrent for the recycling of thermoformed trays has been that of the silicone coating that is applied to the trays, which is necessary to prevent the trays from sticking together when stacked, in which form they are supplied to food and other manufacturers for packaging. The silicone layer is said to compromise the recycling process and prevent the recycled polymer yielded from being reused.

Zibo is one of South Africa’s leading manufacturers of thermoformed PET trays, punnets, clamshells, and similar containers, mainly for the food packaging sector and as such, with regard to its circular economy and sustainability objectives, wishes to increase its use of recycled polymers as well as to reprocess its production scrap.

With plants in Blackheath in the Western Cape and Olifantsfontein in Gauteng, Zibo is the leader in the thermoformed tray sector in South Africa. The wash and decontamination processes allow Zibo to include 30% post-consumer PET in all its products. Where requirements demand, it is possible it is possible to produce trays and punnets from 100% post-consumer rPET.

An estimated 26,000 tons of PET is processed by the thermoforming sector in South Africa. Up till now, none of this material has been recycled, with the bulk of the material going to landfill, so the potential to reuse this material is clearly an incentive for manufacturers.

But Zibo Containers CEO André Smit was not put off by the challenge and, in what is a major capex project, the design and set-up of the plant has proceeded over the past two years. The main washplant unit, from Beier of China, was commissioned earlier this year at the Zibo site in Saxenburg business park in Blackheath near Somerset West.

The line includes conveyors to transport the collected material, a stage for manual sorting, an infrared sorting line from Tomra of Germany (which can detect different polymers, metals and even be set to expel certain colours), and granulators to reduce the containers into flake state, with all this all leading up to the actual Beier washplant. Once washed, in a further step, the flake is dried to allow it to be processed on the Erema line in an adjacent building at the Zibo site.

Switch-on for the washplant took place in early October, with only PET bottle grade material being processed at first, which was necessary in order to ramp the system up progressively and calibrate it before the addition of thermoformed material. The latter was added in progressive levels, with 10% thermoformed material being added as at mid-November. At that point, the system was processing up to 8 tons of material a day and Smit was happy with the results achieved.

Part of the argument against the recycling of PET trays was that PET bottle manufacturers require material with zero traces of silicone, but Smit says this is not a problem for thermoforming tray production. Zibo operates a comprehensively equipped laboratory where, among the tests conducted, checks to detect evidence of the presence of silicone are conducted.

Other problems remain to be resolved, however, including that of labels affixed to thermoformed trays. Labels are also used as a tamper evidence solution, simultaneously sealing the containers too. All label material can be removed in the Zibo process, but a further current restraint is that some of the adhesives used to attach labels are difficult to completely remove. Even in minimal traces, these adhesive materials can contaminate the rPET production stream and hence need to be eliminated, which task is commenced in the washplant and completed in the Erema stage, as with the silicone component.

A major motivation for the recycling project at Zibo was that a number of national brand and retail businesses in South Africa, and globally, now desire to include recycled materials in their packaging containers, or at least percentages thereof, and Zibo is thus meeting this demand.

According to Woolworths Foods’ chief technology and sustainability officer Latiefa Behardien, her company fully supports these objectives: An example of this is our recent switch to an ‘easy wash off’ glue like Cleanflake® which ensures that glue from the packaging’s label washes off entirely in the recycling washing process, leaving no leftover residue to compromise the recycled plastic.”