If the costs and expenses of removing litter is not paid within the time provided, the city council shall, and it is hereby empowered to, levy and assess the costs and expenses of such work upon the property so benefitted. The same shall be levied on all lots, tracts or parcels of land to the extent of the special benefits to such real estate, by reason of such improvement, such benefits to be determined by the city council sitting as a board of equalization after publication in a newspaper having general circulation in the City and personal notice at least ten days prior thereto. The assessments so levied shall be a lien on the property on which levied from the date of levy and shall be due and payable to the city treasurer thirty days after such levy and shall become delinquent fifty days after such levy and shall bear interest at the rate of seven percent per annum from the date they become delinquent; and, at the time of the next certification for general revenue purposes to the county clerk, if not previously paid, the special taxes shall be certified to the county clerk and by him be placed upon the tax list and be collected as other real estate taxes are collected, and be paid over to the city treasurer.