In a lagoon-based wastewater treatment process, reduction of total nitrogen in the product water is facilitated by including a denitrification process. In an initial phase of the overall process, raw wastewater is processed in a lagoon to reduce BOD5 and TSS. Nitrification occurs in the lagoon and/or in a distinct or separate nitrification reactor. At least a portion of product water that has been nitrified is mixed with a portion of raw, incoming wastewater, and the mixture is introduced into an anoxic region of the lagoon in a manner that promotes denitrification within the anoxic region of the lagoon.