To get the landfill recipe for sand to change, the way I done it was to use space-explorations data_util file and use the functions in it

local data_util = require("space-exploration/data_util")

--replace_or_add_result(recipe-name, item-to-replace, new-item, amount)
data_util.replace_or_add_result("landfill", "landfill", "landfill", 10)
data_util.replace_or_add_result("landfill-sand", "landfill", "landfill", 10)

To get the landfill recipe for sand to change, the way I done it was to use space-explorations data_util file and use the functions in it

local data_util = require("__space-exploration__/data_util")

--replace_or_add_result(recipe-name, item-to-replace, new-item, amount)
data_util.replace_or_add_result("landfill", "landfill", "landfill", 10)
data_util.replace_or_add_result("landfill-sand", "landfill", "landfill", 10)

Thank you, it worked, so I'm adding it to the mod.