Aquacultural Engineering 19 (1999) 147 – 161 Treatment of harvest discharge from intensive shrimp ponds by settling D.R. Teichert-Coddington *, D.B. Rouse, A. Potts, C.E. Boyd Department of Fisheries and Allied Aquacultures, Auburn Uniersity, Auburn, AL 36849 -5419, USA Received 9 July 1998; accepted 16 October 1998 Abstract Efﬂuent from intensively managed shrimp ponds was examined during harvest when ponds were drained. Concentrations of nutrients and solids in efﬂuents were signiﬁcantly higher during the ﬁnal 20 cm of discharge (16% of pond volume), but greatest increases occurred during the ﬁnal 5 cm of discharge (3.9% of pond volume). When the ﬁnal 20 cm of pond discharge was allowed to settle, near maximum sedimentation for most variables occurred within 6 h. Settling removed total nitrogen less effectively than other nutrients. Within 6 h, 100% of settleable solids, 88% of total suspended solids, 71% of volatile solids, 63% of biochemical oxygen demand (BOD), 31% of total nitrogen and 55% of total phosphorus had sedimented from the ﬁnal 20 cm of efﬂuent. For the total pond this represented 61% settleable solids, 40% total suspended solids, 24% total volatile solids, 12% BOD, 7% total nitrogen, and 14% total phosphorus. Of the total amount removed during settling, 61% of settleable solids, between 18 and 26% of BOD, nitrogen and phosphorus, and between 34 and 45% volatile and suspended solids were found in the ﬁnal 20 cm of discharge (16% of pond volume). A simple treatment of pond efﬂuents at harvest can be effected by shunting the last 10–20% of discharge through a settling pond with no more than 6-h of residence. © 1999 Elsevier Science B.V. All rights reserved. Keywords: Drainage; Harvest discharge; Shrimp ponds * Corresponding author. Tel.: +1-334-8449208; fax: +1-334-8444786. 0144-8609/99/$ - see front matter © 1999 Elsevier Science B.V. All rights reserved. PII:S0144-8609(98)00047-8