They have to use separate equipment for all halal foods than non-halal. They have to use special cleaning supplies that are compliant and have no non-Halal ingredients.
These chemicals are different than that of non-halal chemicals
"Diatomaceous Earth (DE): Widely used as a halal-compliant cleaning agent, DE is effective in physically scrubbing and purifying surfaces. It is mixed in specific ratios with water depending on the type of utensils, equipment or area being cleaned.
Natural Detergents: Plant-based detergents free from animal derivatives and alcohol are recommended for halal sanitation. These detergents should have verified halal status to ensure compliance.
Non-Ethanol-Based Disinfectants: Disinfectants containing isopropyl alcohol or other permissible alcohols can be used, as they are considered mubah (permissible) in sanitation processes as long as they leave no detectable residue in the finished product."
And procedural what OP might have been looking for when something has been contaminated but IDK the full requirements as to whether this part is truly followed since there are Halal restaurants in my part of the US, idk if they do this part:
"2.4 Sertu (Ritual Cleansing)
Sertu is a ritual cleansing process used when major najis such as porcine or dog contaminants has come into contact with a product surface or equipment. This process involves washing the contaminated area seven times, with at least one wash including a mixture of water and earth, to purify the area both physically and spiritually."
I mean, not for a lot of food production. We had Halal cert at our grain mill and a few other places I've worked at, and we never treated the food differently. Same with Kosher. They just send someone out to extort your business for certificate renewal.