Pre-treatment of waste feedstocks for biodiesel production

The decision to use waste feedstocks for biodiesel production was driven by a series of socio-political choices that revolutionised the demand and, consequently, the supply of fuel from renewable sources.

The market for biofuels, and biodiesel in particular, has exploded in recent years, mainly as a result of the need to lower CO₂ emissions, which led to the mandatory blending of biodiesel with fossil diesel.

The sudden and necessary demand for biodiesel has presented both biofuels and conventional diesel producers with a number of challenges. First of all, the European market, the main recipient of CO₂ reduction regulations, had already adopted catalytic converters to trap the particulate matter resulting from the combustion of fossil diesel. Here the first problem arises because, although the obligation to be achieved by 2030 is that of a minimum percentage of 14% of fuel of renewable origin out of the total, most engines on the market can tolerate a maximum mixture of 7%.

Moreover, from both ethical and practical point of view, it is not far-sighted to put the fuel production against the same raw material used for food, causing – moreover –  an increase in production costs and a reduction in profit margins. This was also in light of the sudden proliferation of biodiesel producers in the face of intense market demand.

The solution was to use waste feedstocks for biofuel (HVO, SAF or biodiesel) production, since they cannot be used for food purposes, can take advantage of the so-called “double-counting” mechanism, doubling the percentage weight when blended with conventional diesel. Basically, by adding 7% of so-called biofuel  produced from waste feedstocks, it is as if the percentage were doubled, reaching the 14% required by European  regulation. However, extensive pre-treatment of waste feedstocks for biofuel production is required, due to the nature of such feedstocks.

Technology advantages

There are different types of waste feedstock pre-treatment of for biofuel production:

• UCO

UCOs of European origin are good raw materials; they have an acidity not normally exceeding 8% and a MIU (moisture, impurities and unsaponifiable matter) in the order of 3%. Typical treatment consists of bleaching to absorb solid impurities and stripping  to remove acidity. The quantity on the market is limited and prices are high. For this reason, materials of different origins are common. The qualities of these materials vary widely, but in principle the pretreatment should not differ too much.

• POME

POME is a low grade feedstocks which became more and more used in the last years. The acidity of POME is variable but high, on average 40-50 %. Impurities can reach 1.5 %, are sticky and have a tendency to foam. Typical treatment is decanting followed by dry degumming and bleaching with Niagara filter, to be selected properly according to the quality of the treated POME. This material can be used directly in enzymatic process, while glycerolysis is required to convert the acidity into glycerides if a conventional transesterification plant is used.

• OIL FROM SEWERS

Pretreatment varies according to the characteristics of the raw material, but in principle is similar to POME. Normally, oil from sewage is only mixed in small quantities with the raw material.

• LOW GRADE ANIMAL FATS

The treatment normally requires dry degumming and bleaching, with the addition of a higher- than-normal mineral acidity if proteins are present. Special treatment is necessary if the PE content is high. Deacidification can be carried out with a stripper, if the FFA does not exceed 15 % or with glycerolysis. As with POME, treated animal fat can be used in the enzymatic process.

• SOAPSTOCK FATTY ACIDS

May contain residual amounts of sulfuric acid from the soapstock splitting. Washing with water may be necessary. This is followed by glycerolysis or directly by enzymatic plant.

• RAW MATERIALS TO BE USED FOR HVO

Normally require extensive treatment based on two bleaching steps to reduce the amount of metals that are poisonous  to the catalysed conversion reaction.

Acidity is not a problem, it does not affect most of the conversion processes.

Further advantages of CMB technology

CMB is able to offer an  integrated service according to the Client’s production needs, thanks to the great experience and in-depth knowledge of its engineers and technicians concerning the biodiesel production.

CMB’s experts, as they have already done for several companies in Europe and the rest of the world, can upgrade an existing transesterification plant, adding a pre-treatment unit or they can provide a new enzymatic biodiesel production plant, capable of accessing an even wider range of waste feedstocks, with a more direct process, while retaining the advantages of full flexibility in the market.

Summarising the benefits that Clients can obtain by entrusting CMB with the upgrade of one of its plants or the construction of a new enzymatic biodiesel production plant, we can list:

• Flexibility in the market for the sourcing of a wide range of raw materials;
• Extensive experience in state-of-the-art biodiesel production;
• Competitive costs;
• Tailor-made solutions according to Client’s needs;
• In-house plants design and construction using best-in-class materials;

Contact us right now for a smart consultation with our professionals and find out how CMB can help you to boost your business! Write us now to: info@cmb.it