I have an ant problem in my house, specially in the kitchen, where they seem to have taken over. Just found out that they have cut through the plastic packaging of some food items and gotten inside. Is there a non-toxic pesticide or repellent I could use to drive them away? I have used turmeric powder before, and it is kinda effective, specially if you make a paste and stick it where the ants enter from. But I'd prefer not getting turmeric everywhere, and since I can't exactly find out where the ants are coming from, it wouldn't be as effective anyways.
You should try boric acid. Yes, it is an acid, but it is safe enough to be used as an eye wash for medical purposes. It is also toxic to ants and safe to use around the kitchen. I'm not sure if you consider it sustainable or not, but mixed with powdered salt or sugar, it gets rid of ants quite effectively.
I'm not quite clear on what you mean about non-toxic in the question. Do you mean non-toxic to ants or to people and pets?
I would suggest baking soda. It is very effective against ants, cheap and available in the supermarket. Just put some on the areas that frequented by the ants and if you can locate the points they enter your house and put some there. A chemical reaction I can't describe right now will kill the ants when they eat the powder. I had the same problem with my pot plants which ants used as a nesting location and got rid of them with baking soda. Keep in mind that ants are protected species in some areas so I would be careful before you use it on the nest.
There are several products on the market that use mint oil such as this one. While I haven't used the one linked, I have used ones sold at home depot branded as "safer" and they worked well. I sometimes had to do multiple applications over time, but in the long run, the ants subsided. In my case, I had sugar ants.
Rubbing alcohol will prevent all insects. Of course, it doesn't last very long.
Clove powder will kill ants, even causing burning to them if it is just sprinkled on top of them. But, I do not know the way to get cinnon into the hive. If put along the edges, it will be extremely effective at first but after the worst part of the oils wear off they may find a way through if you are not careful with every pixel covered.
Borax kills ants if they eat it.
Some ants are attracted to sugar water. So using this to attract them into a drowning bowl etc. However, some ants are not attracted to it.
Orange peels and water in the blender, to make a paste, will kill the outdoor ant colony if you can find the entrances to their hills in your yard, if applicable. All entraces and exists need to be covered for this to work permanantly. Cover the hole with the paste. It is the equivalent of closing your windows and pumping in a poisonous gas.
O3 will kill every organism in the building, as well as remove all smells. To use O3, the house will need to be evacuated, and aired with windows opem for 2 days afterwards before the family moves back in.
There are electromagnetic ant repellents. Ants cannot stand the waves emitted by these devices. The device can be plugged into the wall socket. This is safe, harmless to humans and pets, noiseless, clean and hygienic. Energy consumption is about 5W.
These devices are sold at many places. Unfortunately there is no irrefutable scientific evidence of their effect.
What I personally tried is boiling about 5 lit water in a big pot and pouring this 100 C hot water into their hole. Unfortunately it works only outside. A bit primitive, but effective.