A field-scale 4-celled, horizontal subsurface constructed wetland (CW) was installed to evaluate removal efficiencies of wastewater constituents in an industrial distillery effluent. Total and dissolved solids, NH4-N, TKN, P and COD were measured. This CW design provides four serial cells with synthetic liners and a river gravel base. The first two unplanted cells provide preliminary treatment. Specific gravel depths and ensuing biofilm growth provides anaerobic treatment in Cell 1 and anaerobic treatment in Cell 2. Cell 3 was planted with Typha latifolia with an inserted layer of brick rubble (for phosphorus removal). Locally grown reed, Phragmites karka was planted in Cell 4. COD was reduced from 8420 mg/l 3000 from Cell 1 to the outlet of Cell 4. Likewise other parameters: total and dissolved solids, ammonium and total nitrogen, and total P, indicated declining trends at the 4-celled CW effluent. This study reveals how high strength distillery wastewater strongly impacts morphology, aeration anatomy in the chiseled plant tissues, reed growth; and composition of the biofilm in the specialized substratum. The reliability of a CW for organic and nutrients reduction, in association with a poorly performing conventional system is discussed. There is an immense potential for appropriately designed constructed wetlands to improve high strength wastewaters in India.

Treatment performance of a field-scale horizontal subsurface (SF) constructed wetland (CW) was evaluated for removal efficiency of BOD, TSS, NH4-N, NO3-N, TKN and P from municipal wastewater emanating from a small community of residential areas in Ujjain, Central India. The SF wetland had a rectangular size and covered an effective surface area of 41.82 m2 with a water retention capacity of 18 m3. The SF medium was composed of a gravel bed supported below on a layer of puddled local clay and overlaid by a thin synthetic liner. CW was planted initially with locally grown grass, Phragmites karka. Plants placed in this rectangular design at the rate of 3 to 4 plants per m2 increased to 6157 plants within ten months producing a biomass of 121 tonnes ha−1. The influent was pretreated before entering the SF system, through two baffles; a grass covered small ditch, followed by a narrow tunnel of packed biofilmed boulders. Removal rates of TSS (48%), TKN (36%), NH4-N (22%) and NO3-N as zero percent were realised. An earthen channel provided initial pretreatment by a land treatment system. Average treatment performance after five months from this SF system recorded removal efficiencies of 78% for NH4-N, TSS; 58-65% for P, BOD and TKN. Effluent dissolved oxygen levels increased to 34% indicating existence of aerobic conditions in the rooted-gravel bed. The SF system overall results established: (a) very cost-effective treatment technology, (b) SF removal efficiency above 50% for BOD, NH4-N, TKN, and P. This SF system presents a unique design consideration compared with the land-intensive Kickuth standard system design.

The discharge of untreated wastewater in River Kshipra had brought annual average of BOD, TKN and TS levels up to 39 mg/l, 38 mg/l and 781 mg/l respectively in the study area. Treatment performance by Artificial Floating Reed Beds (AFRB) was evaluated for removal efficiency of TS, NH4-N, NO3-N, TKN and BOD from river water, initially, under a pilot scale by an AFRB of size 200 m2 planted with local reed grass, Phragmites karka, in the part of River Kshipra at the confluence with meeting point of a wastewater stream. The system performance was recorded as 43% reduction in TS, 38% reduction in TKN and 39% BOD reduction. The experimental AFRBs were buoyant structure planted with reed grass, each unit had a rectangular size and covered an effective surface area of 2 m2. The experiment with the mesocosms with treatment of River water resulted that AFRB was reducing pollution load by 55-60% of TS, 45-55% of NH4-N, 33-45% of NO3-N, 45-50% of TKN and 40-50% of BOD. AFRB may be recommended as an in-situ, eco-friendly river water treatment structures for small shallow, slow flowing (or slightly stagnant) water bodies.

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