By contrast, the suspended solids were expected to be 550 milligrams per litre. They are 1800 milligrams per litre which may be due to too much gas production in the quiescent zone of the reactor keeping the sludge particles suspended. In addition, the presence of filamentous bacteria might contribute to the high suspended solids. This bacteria could be attributable to high loading levels, poor nitrogen balance in the feed, and problems during the early years of operation. System costs Capital costs for anaerobic treatment processes tend to be higher than for aerobic treatment processes.
Variable costs tend to be lower.
The variable costs per cubic metre of methane recovered without the trade waste charges are about 15 cents. A local planning permit and EPA works approvals were required to construct the system. Because the system is covered it did not need the same EPA approvals as an open system would have required. A feasibility study is being undertaken into the economics of producing electricity for the site, and to use the gas for producing steam and hot water for the plant. There is the possibility that an increase in spray drying would reduce the amount of milk used for cheese production.