Zero residue plant oriented to dairy sector

Location and site

LuGaZ facility is projected in the industrial park of the city of Lugo, more precisely, in the milk processing plant of LECHE RÍO. The area of waste feedstock generation will be in the vicinities of the city of Lugo, where the LuGaZ SPV identified a sustainable production of waste streams that will allow the facility to operate in the upcoming 20 years. Indeed, one of its members, AGROAMB, has a wider expertise in residues management and they are treating right now more than 10 times the amount required in LuGaZ. Moreover, LuGaZ has been conceived as opposed to existing biogas plants concepts or waste treatment centres, since the project partners have considered organic feedstocks that are available in the area. The goal is to avoid unnecessary waste transportation costs and emissions and promote local development. Future replication of the technology aimed at expansion will also follow this principle, as it will be based on set up of next Zero residue plants to treat agri-food waste locally. On the other side, the presence of a readily available grid gas injection point was crucial to decide the set-up location of LuGaZ plant.

Technological solution 

Regarding the technology selected, AD is the core of the process, due to the possibility of bioenergy production from the residues generated by LECHE RÍO and their associated farmers. Moreover, a co-digestion with AGROAMB local residues (e.g. sludge, lipids, etc) is proposed to overcome limitations offered by mono-digestion processes of only manure or sludge. The use of co-substrates can increase the biogas yield of digesters due to the synergies occurred between them.  

LuGaZ is a first-of-a-kind facility that combines a unique set of technologies: a biogas plant for local wastes combined to an innovative upgrading system allowing CO2 reuse in close facilities (i.e LECHE RÍO wastewater) and a whole treatment system for digestate separation and valorisation thorough reusable water and fertiliser. It could be divided in the following modules: 

• Transport and reception area: dealing with the logistics and reception of feedstocks, will comprise a facility where all the waste handling and pre-treatment is performed. The inputs in this case will be: (1) the sludge coming from the physico-chemical treatment of the dairy plant; (2) the cow manure from LECHE RÍO farmers; and organic residues close to LuGaZ plant coming from the residues already managed from AGROAMB company.  

• Feed optimization and AD: AD is the core of the process due to the possibility of bioenergy production from the residues generated by LECHE RÍO and their associated farmers along with other AGROAMB local residues (e.g. sludge, lipids, etc). Anaerobic co-digestion will be optimized by OPTIBLENDER® specialized software. 
• Biogas upgrading and feed into the gas grid: an innovative upgrading system will ensure biogas conversion into biomethane, suitable for injection to the NG grid; but also, the reuse of eliminated CO2 in close facilities. An ad hoc system designed for small scale plants with minimum energy requirements coming from patented NIDUP TROVANT TECHNOLOGY will be applied.  
• Digestate valorization: treatment to reach water reuse in closing areas (for instance for gardens, cleaning truck installations, etc.), allowing also future recovering of nutrients for useful applications that can be returned for farmers in rural areas. DEPURGAN/AQUATEC technology will be applied as low-cost technology for liquid digestate at small-scale farming system.