AIG Highstar Capital has acquired Interstate Waste Services Inc., a Sloatsburg, N.Y.-based municipal solid waste company, from backers including Summer Street Capital and Ironwood Capital. No financial terms were disclosed. Goldsmith Agio Helms advised IWS on the deal.

Audax Group has acquired AAMP of America from ICV Capital Partners for an undisclosed amount. AAMP is a Clearwater, Fla.-based maker of 12-volt mobile audio after-market accessories.

Castle Harlan has completed its $110 million purchase of AmeriCast Technologies Inc. from KPS Special Situations Fund. AmeriCast is an Atchison, Kansas-based maker of complex steel castings.

Nautic Partners has sponsored a management buyout of Precision Engineered Products Inc. from The Jordan Co. PEP is an Attleboro, Mass.-based maker of fabricated parts, technical surface finishes, specialty and clad metals and micron tolerance-molded plastic components. No financial terms were disclosed for the deal, which included senior leverage arranged by GE Antares Capital.

MidOcean Partners has agreed to acquire a 50% ownership position in Prism Business Media, upon Prism’s completion of its previously-announced acquisition of Penton Media. The stake will be sold by Prism owners Wasserstein & Co., Highfields Capital Management and Lexington Partners. No financial terms are being disclosed.

MidOcean Partners has agreed to sell its interest in Thompson Publishing Group to Avista Capital Partners. No financial terms were disclosed. Thompson Publishing is a Washington, D.C.-based provider of subscription-based information services. MidOcean acquired its interest in May 2004, and one year later helped back the company’s strategic acquisition of Sheshunoff. Avista acquired a position from Credit Suisse earlier this year.