The officer making such sale shall execute a deed to the purchaser, which shall convey all the right, title, and interest which the party against whose property the assessment was made had or held in said property at the date of making such assessment or on the date of making such sale. Any surplus arising from said sale shall be paid to the city or town treasurer to be kept as a separate fund by the treasurer for the owner upon the responsibility of his official bond. The council may, by its agents, purchase real estate sold as provided under this article and, in the event of such purchase, the deed for the same shall be made to the town or city.