A constructed wetland structure, comprising a water inlet pond (1), a first unit (2), a plurality of middle units (3), and a tail unit (4), and a water storage pond (5), with the water inlet pond (1), the first unit (2), the plurality of middle units (3), the tail unit (4), and the water storage pond (5) communicating in sequence,
- wherein the first unit (2), the plurality of middle units (3), and the tail unit (4) are provided with a bottom plate (6), a drainage channel (7), a permeable plate (8), a bottom layer substrate (9), a middle layer substrate (10), a top layer substrate (11), and wetland plants (12) from bottom to top in sequence;
- wherein an internal parting wall (19) of the water inlet pond (1), a plurality of unit partition walls (20), and an internal parting wall (23) of the water storage pond (5) are arranged among the water inlet pond (1), the first unit (2), the plurality of middle units (3), the tail unit (4), and the water storage pond (5);
- wherein the water inlet pond (1), the first unit (2), the plurality of middle units (3), the tail unit (4), and the water storage pond (5) communicate through a water inlet (18) in the internal parting wall (19), and water outlets (21) respectively in the plurality of unit partition walls (20) and in the internal parting wall (23);
- wherein a filter block (27) is arranged in each of the water inlet (18) and water outlets (21);
- wherein an upper carbon source layer (13), a lower carbon source layer (14), a carbon source injection pipe (15), and a connecting pipe (16) are arranged in each of the first unit (2), the plurality of middle units (3), and the tail unit (4), and the carbon source injection pipe (15) is longitudinally arranged and communicates with the upper carbon source layer (13) and the lower carbon source layer (14) through the connecting pipe (16);
- wherein the upper carbon source layer (13) in the first unit (2) is arranged in the middle of the middle layer substrate (10), the lower carbon source layer (14) is arranged between the middle layer substrate (10) and the bottom layer substrate (9), and carbon source materials are arranged in the upper carbon source layer (13) and the lower carbon source layer (14);
- wherein, counting from a most upstream middle unit (3) among the plurality of middle units (3), the upper carbon source layer (13) in an odd-numbered middle unit (3) among the plurality of middle units (3) is arranged between the middle layer substrate (10) and the top layer substrate (11), and the lower carbon source layer (14) is arranged in the middle of the middle layer substrate (10);
- and the upper carbon source layer (13) in an even-numbered middle unit (3) among the plurality of middle units (3) is arranged in the middle of the middle layer substrate (10), and the lower carbon source layer (14) is arranged between the middle layer substrate (10) and the bottom layer substrate (9);
- wherein the water inlet (18) between the first unit (2) and the water inlet pond (1) is formed at a lower end of the internal parting wall of the water inlet pond (19), the water outlet (21) between the odd-numbered middle unit (3) among the plurality of middle units (3) and any directly upstream middle unit (3) among the plurality of middle units (3) or the first unit (2) is formed at an upper end of one unit partition wall of the plurality of unit partition walls (20) and above the top layer substrate (11), and the water outlet (21) between the even-numbered middle unit (3) among the plurality of middle units (3) and any directly upstream middle unit (3) among the plurality of middle units (3) is formed at the lower end of one unit partition wall of the plurality of the unit partition walls (20) and below the bottom layer substrate (9);
- wherein when a total number of the plurality of middle units (3) is even, the upper carbon source layer (13) in the tail unit (4) is arranged between the middle layer substrate (10) and the top layer substrate (11), and the lower carbon source layer (14) is arranged in the middle of the middle layer substrate (10);
- the water outlet (21) between the tail unit (4) and a directly upstream middle unit (3) among the plurality of middle units (3) is formed at the upper end of one unit partition wall of the plurality of the unit partition walls (20), and the water outlet (21) between the tail unit (4) and the water storage pond (5) is formed at the lower end of the internal parting wall of the water storage pond (23);
- wherein when a total number of the plurality of middle units (3) is odd, the upper carbon source layer (13) in the tail unit (4) is arranged in the middle of the middle layer substrate (10), and the lower carbon source layer (14) is arranged between the middle layer substrate (10) and the bottom layer substrate (9);
- the water outlet (21) between the tail unit (4) and a directly upstream middle unit (3) among the plurality of middle units (3) is formed at the lower end of one unit partition wall of the plurality of the unit partition walls (20), and the water outlet (21) between the tail unit (4) and the water storage pond (5) is formed at the upper end of the internal parting wall of the water storage pond (23);
- wherein the upper carbon source layer (13) and the lower carbon source layer (14) are same in structure and each comprises a plurality of screen pipes (26), and the carbon source material is arranged in the screen pipes (26);
- wherein the plurality of screen pipes (26) are arranged in a water flow direction, and the screen pipes (26) have a diameter of 100-200 mm, a pore diameter of 5-10 mm, and a hole pitch of 2-5 mm;
- and the spacing between two adjacent screen pipes (26) is 1.0-2.2 meters;
- wherein the carbon source material comprises treated modified plant straws, modified straw biochar, and modified woody biochar particles at a mass ratio in a range of 40:30:30 to 65:20:15, respectively.